Would a plant need light if the chemicals gained by photosynthesis were given through the roots or as a foliar spray?

Would a plant need light if the chemicals gained by photosynthesis were given through the roots or as a foliar spray?

We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

If you took the chemicals a plant gains through photosynthesis and put it through the plants' roots or by injection, or used as a foliar application for intake through the stomata, would the plant need light? If not, how would it respond to the treatment?

Not exactly the same thing, but a species of algae has been genetically altered to allow it to uptake glucose, bypassing the need for photosynthesis:

I doubt this would work for the vast majority of plants. I think it would cause root rot as the microorganisms in the soil would out-compete the plant. Also the transport systems of the plant might not be efficient in this direction.

I mean might there be a plant somewhere where this might work? Sure. Fungi that grow in the dark would be a lot like such plants, so its biologically possible. There might be a primitive plant that doesn't need its chloroplast to be active to live. I've never heard of one and wikipedia is not helping here…

All living things are carbon based. Carbon atoms bond with other atoms to form chains such as proteins, fats and carbohydrates, which in turn provides other living things with nourishment. The role then of carbon in plants is called the carbon cycle.

Plants use carbon dioxide during photosynthesis, the process whereby the plant converts the energy from the sun into a chemical carbohydrate molecule. Plants use this carbon chemical to grow. Once the plant’s life cycle is over and it decomposes, carbon dioxide is formed again to return to the atmosphere and begin the cycle anew.


Carbon, hydrogen and oxygen are the basic nutrients plants receive from air and water. Justus von Liebig proved in 1840 that plants needed nitrogen, potassium and phosphorus. Liebig's law of the minimum states that a plant's growth is limited by nutrient deficiency. [5] Plant cultivation in media other than soil was used by Arnon and Stout in 1939 to show that molybdenum was essential to tomato growth.

Plants take up essential elements from the soil through their roots and from the air (mainly consisting of nitrogen and oxygen) through their leaves. Nutrient uptake in the soil is achieved by cation exchange, wherein root hairs pump hydrogen ions (H + ) into the soil through proton pumps. These hydrogen ions displace cations attached to negatively charged soil particles so that the cations are available for uptake by the root. In the leaves, stomata open to take in carbon dioxide and expel oxygen. The carbon dioxide molecules are used as the carbon source in photosynthesis.

The root, especially the root hair, is the essential organ for the uptake of nutrients. The structure and architecture of the root can alter the rate of nutrient uptake. Nutrient ions are transported to the center of the root, the stele, in order for the nutrients to reach the conducting tissues, xylem and phloem. [6] The Casparian strip, a cell wall outside the stele but within the root, prevents passive flow of water and nutrients, helping to regulate the uptake of nutrients and water. Xylem moves water and mineral ions within the plant and phloem accounts for organic molecule transportation. Water potential plays a key role in a plant's nutrient uptake. If the water potential is more negative within the plant than the surrounding soils, the nutrients will move from the region of higher solute concentration—in the soil—to the area of lower solute concentration - in the plant.

There are three fundamental ways plants uptake nutrients through the root:

    occurs when a nonpolar molecule, such as O2, CO2, and NH3 follows a concentration gradient, moving passively through the cell lipid bilayer membrane without the use of transport proteins. is the rapid movement of solutes or ions following a concentration gradient, facilitated by transport proteins. is the uptake by cells of ions or molecules against a concentration gradient this requires an energy source, usually ATP, to power molecular pumps that move the ions or molecules through the membrane.

Nutrients can be moved within plants to where they are most needed. For example, a plant will try to supply more nutrients to its younger leaves than to its older ones. When nutrients are mobile within the plant, symptoms of any deficiency become apparent first on the older leaves. However, not all nutrients are equally mobile. Nitrogen, phosphorus, and potassium are mobile nutrients while the others have varying degrees of mobility. When a less-mobile nutrient is deficient, the younger leaves suffer because the nutrient does not move up to them but stays in the older leaves. This phenomenon is helpful in determining which nutrients a plant may be lacking.

Many plants engage in symbiosis with microorganisms. Two important types of these relationship are

  1. with bacteria such as rhizobia, that carry out biological nitrogen fixation, in which atmospheric nitrogen (N2) is converted into ammonium (NH +
    4 ) and
  2. with mycorrhizal fungi, which through their association with the plant roots help to create a larger effective root surface area. Both of these mutualistic relationships enhance nutrient uptake. [6]

The Earth's atmosphere contains over 78 percent nitrogen. Plants called legumes, including the agricultural crops alfalfa and soybeans, widely grown by farmers, harbour nitrogen-fixing bacteria that can convert atmopheric nitrogen into nitrogen the plant can use. Plants not classified as legumes such as wheat, corn and rice rely on nitrogen compounds present in the soil to support their growth. These can be supplied by mineralization of soil organic matter or added plant residues, nitrogen fixing bacteria, animal waste, through the breaking of triple bonded N2 molecules by lightning strikes or through the application of fertilizers.

At least 17 elements are known to be essential nutrients for plants. In relatively large amounts, the soil supplies nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur these are often called the macronutrients. In relatively small amounts, the soil supplies iron, manganese, boron, molybdenum, copper, zinc, chlorine, and cobalt, the so-called micronutrients. Nutrients must be available not only in sufficient amounts but also in appropriate ratios.

Plant nutrition is a difficult subject to understand completely, partially because of the variation between different plants and even between different species or individuals of a given clone. Elements present at low levels may cause deficiency symptoms, and toxicity is possible at levels that are too high. Furthermore, deficiency of one element may present as symptoms of toxicity from another element, and vice versa. An abundance of one nutrient may cause a deficiency of another nutrient. For example, K + uptake can be influenced by the amount of NH +
4 available. [6]

Nitrogen is plentiful in the Earth's atmosphere, and a number of commercially-important agricultural plants engage in nitrogen fixation (conversion of atmospheric nitrogen to a biologically useful form). However, plants mostly receive their nitrogen through the soil, where it is already converted in biological useful form. This is important because the nitrogen in the atmosphere is too large for the plant to consume, and takes a lot of energy to convert into smaller forms. These include soybeans, edible beans and peas as well as clovers and alfalfa used primarily for feeding livestock. Plants such as the commercially-important corn, wheat, oats, barley and rice require nitrogen compounds to be present in the soil in which they grow.

Carbon and oxygen are absorbed from the air while other nutrients are absorbed from the soil. Green plants ordinarily obtain their carbohydrate supply from the carbon dioxide in the air by the process of photosynthesis. Each of these nutrients is used in a different place for a different essential function. [7]

Basic nutrients Edit

The basic nutrients are derived from air and water. [8]

Carbon Edit

Carbon forms the backbone of most plant biomolecules, including proteins, starches and cellulose. Carbon is fixed through photosynthesis this converts carbon dioxide from the air into carbohydrates which are used to store and transport energy within the plant.

Hydrogen Edit

Hydrogen is necessary for building sugars and building the plant. It is obtained almost entirely from water. Hydrogen ions are imperative for a proton gradient to help drive the electron transport chain in photosynthesis and for respiration. [6]

Oxygen Edit

Oxygen is a component of many organic and inorganic molecules within the plant, and is acquired in many forms. These include: O2 and CO2 (mainly from the air via leaves) and H2O, NO −
3 , H2PO −
4 and SO 2−
4 (mainly from the soil water via roots). Plants produce oxygen gas (O2) along with glucose during photosynthesis but then require O2 to undergo aerobic cellular respiration and break down this glucose to produce ATP.

Macronutrients (primary) Edit

Nitrogen Edit

Nitrogen is a major constituent of several of the most important plant substances. For example, nitrogen compounds comprise 40% to 50% of the dry matter of protoplasm, and it is a constituent of amino acids, the building blocks of proteins. [9] It is also an essential constituent of chlorophyll. [10] In many agricultural settings, nitrogen is the limiting nutrient for rapid growth.

Phosphorus Edit

Like nitrogen, phosphorus is involved with many vital plant processes. Within a plant, it is present mainly as a structural component of the nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), as well as a constituent of fatty phospholipids, that are important in membrane development and function. It is present in both organic and inorganic forms, both of which are readily translocated within the plant. All energy transfers in the cell are critically dependent on phosphorus. As with all living things, phosphorus is part of the Adenosine triphosphate (ATP), which is of immediate use in all processes that require energy with the cells. Phosphorus can also be used to modify the activity of various enzymes by phosphorylation, and is used for cell signaling. Phosphorus is concentrated at the most actively growing points of a plant and stored within seeds in anticipation of their germination.

Potassium Edit

Unlike other major elements, potassium does not enter into the composition of any of the important plant constituents involved in metabolism, [9] but it does occur in all parts of plants in substantial amounts. It is essential for enzyme acitivity including enzymes involved in primary metabolism. It plays a role in turgor regulation, effecting the functioning of the stomata and cell volume growth. [11]

It seems to be of particular importance in leaves and at growing points. Potassium is outstanding among the nutrient elements for its mobility and solubility within plant tissues.

Processes involving potassium include the formation of carbohydrates and proteins, the regulation of internal plant moisture, as a catalyst and condensing agent of complex substances, as an accelerator of enzyme action, and as contributor to photosynthesis, especially under low light intensity. Potassiumregulates the opening and closing of the stomata by a potassium ion pump. Since stomata are important in water regulation, potassium regulates water loss from the leaves and increases drought tolerance. Potassium serves as an activator of enzymes used in photosynthesis and respiration. [6] Potassium is used to build cellulose and aids in photosynthesis by the formation of a chlorophyll precursor. The potassium ion (K + ) is highly mobile and can aid in balancing the anion (negative) charges within the plant. A relationship between potassium nutrition and cold resistance has been found in several tree species, including two species of spruce. [12] Potassium helps in fruit coloration, shape and also increases its brix. Hence, quality fruits are produced in potassium-rich soils.

Research has linked K + transport with auxin homeostasis, cell signaling, cell expansion, membrane trafficking and phloem transport. [11]

Macronutrients (secondary and tertiary) Edit

Sulfur Edit

Sulfur is a structural component of some amino acids (including cystein and methionine) and vitamins, and is essential for chloroplast growth and function it is found in the iron-sulfur complexes of the electron transport chains in photosynthesis. It is needed for N2 fixation by legumes, and the conversion of nitrate into amino acids and then into protein. [13]

Calcium Edit

Calcium in plants occurs chiefly in the leaves, with lower concentrations in seeds, fruits, and roots. A major function is as a constituent of cell walls. When coupled with certain acidic compounds of the jelly-like pectins of the middle lamella, calcium forms an insoluble salt. It is also intimately involved in meristems, and is particularly important in root development, with roles in cell division, cell elongation, and the detoxification of hydrogen ions. Other functions attributed to calcium are the neutralization of organic acids inhibition of some potassium-activated ions and a role in nitrogen absorption. A notable feature of calcium-deficient plants is a defective root system. [14] Roots are usually affected before above-ground parts. [15] Blossom end rot is also a result of inadequate calcium. [16]

Calcium regulates transport of other nutrients into the plant and is also involved in the activation of certain plant enzymes. Calcium deficiency results in stunting. This nutrient is involved in photosynthesis and plant structure. [16] [17] It is needed as a balancing cation for anions in the vacuole and as an intracellular messenger in the cytosol. [18]

Magnesium Edit

The outstanding role of magnesium in plant nutrition is as a constituent of the chlorophyll molecule. As a carrier, it is also involved in numerous enzyme reactions as an effective activator, in which it is closely associated with energy-supplying phosphorus compounds.

Micro-nutrients Edit

Plants are able sufficiently to accumulate most trace elements. Some plants are sensitive indicators of the chemical environment in which they grow (Dunn 1991), [19] and some plants have barrier mechanisms that exclude or limit the uptake of a particular element or ion species, e.g., alder twigs commonly accumulate molybdenum but not arsenic, whereas the reverse is true of spruce bark (Dunn 1991). [19] Otherwise, a plant can integrate the geochemical signature of the soil mass permeated by its root system together with the contained groundwaters. Sampling is facilitated by the tendency of many elements to accumulate in tissues at the plant's extremities. Some micronutrients can be applied as seed coatings.

Iron Edit

Iron is necessary for photosynthesis and is present as an enzyme cofactor in plants. Iron deficiency can result in interveinal chlorosis and necrosis. Iron is not a structural part of chlorophyll but very much essential for its synthesis. Copper deficiency can be responsible for promoting an iron deficiency. [20] It helps in the electron transport of plant.

Molybdenum Edit

Molybdenum is a cofactor to enzymes important in building amino acids and is involved in nitrogen metabolism. Molybdenum is part of the nitrate reductase enzyme (needed for the reduction of nitrate) and the nitrogenase enzyme (required for biological nitrogen fixation). [10] Reduced productivity as a result of molybdenum deficiency is usually associated with the reduced activity of one or more of these enzymes.

Boron Edit

Boron has many functions within a plant: it affects flowering and fruiting, pollen germination, cell division, and active salt absorption. The metabolism of amino acids and proteins, carbohydrates, calcium, and water are strongly affected by boron. Many of those listed functions may be embodied by its function in moving the highly polar sugars through cell membranes by reducing their polarity and hence the energy needed to pass the sugar. If sugar cannot pass to the fastest growing parts rapidly enough, those parts die.

Copper Edit

Copper is important for photosynthesis. Symptoms for copper deficiency include chlorosis. It is involved in many enzyme processes necessary for proper photosynthesis involved in the manufacture of lignin (cell walls) and involved in grain production. It is also hard to find in some soil conditions.

Manganese Edit

Manganese is necessary for photosynthesis, [17] including the building of chloroplasts. Manganese deficiency may result in coloration abnormalities, such as discolored spots on the foliage.

Sodium Edit

Sodium is involved in the regeneration of phosphoenolpyruvate in CAM and C4 plants. Sodium can potentially replace potassium's regulation of stomatal opening and closing. [6]

  • Essential for C4 plants rather C3
  • Substitution of K by Na: Plants can be classified into four groups:
  1. Group A—a high proportion of K can be replaced by Na and stimulate the growth, which cannot be achieved by the application of K
  2. Group B—specific growth responses to Na are observed but they are much less distinct
  3. Group C—Only minor substitution is possible and Na has no effect
  4. Group D—No substitution occurs
  • Stimulate the growth—increase leaf area and stomata. Improves the water balance
  • Na functions in metabolism
  1. C4 metabolism
  2. Impair the conversion of pyruvate to phosphoenol-pyruvate
  3. Reduce the photosystem II activity and ultrastructural changes in mesophyll chloroplast
  • Replacing K functions
  1. Internal osmoticum
  2. Stomatal function
  3. Photosynthesis
  4. Counteraction in long distance transport
  5. Enzyme activation
  • Improves the crop quality e.g. improves the taste of carrots by increasing sucrose

Zinc Edit

Zinc is required in a large number of enzymes and plays an essential role in DNA transcription. A typical symptom of zinc deficiency is the stunted growth of leaves, commonly known as "little leaf" and is caused by the oxidative degradation of the growth hormone auxin.

Nickel Edit

In higher plants, nickel is absorbed by plants in the form of Ni 2+ ion. Nickel is essential for activation of urease, an enzyme involved with nitrogen metabolism that is required to process urea. Without nickel, toxic levels of urea accumulate, leading to the formation of necrotic lesions. In lower plants, nickel activates several enzymes involved in a variety of processes, and can substitute for zinc and iron as a cofactor in some enzymes. [2]

Chlorine Edit

Chlorine, as compounded chloride, is necessary for osmosis and ionic balance it also plays a role in photosynthesis.

Cobalt Edit

Cobalt has proven to be beneficial to at least some plants although it does not appear to be essential for most species. [21] It has, however, been shown to be essential for nitrogen fixation by the nitrogen-fixing bacteria associated with legumes and other plants. [21]

Silicon Edit

Silicon is not considered an essential element for plant growth and development. It is always found in abundance in the environment and hence if needed it is available. It is found in the structures of plants and improves the health of plants. [22]

In plants, silicon has been shown in experiments to strengthen cell walls, improve plant strength, health, and productivity. [23] There have been studies showing evidence of silicon improving drought and frost resistance, decreasing lodging potential and boosting the plant's natural pest and disease fighting systems. [24] Silicon has also been shown to improve plant vigor and physiology by improving root mass and density, and increasing above ground plant biomass and crop yields. [23] Silicon is currently under consideration by the Association of American Plant Food Control Officials (AAPFCO) for elevation to the status of a "plant beneficial substance". [25] [26]

Vanadium Edit

Vanadium may be required by some plants, but at very low concentrations. It may also be substituting for molybdenum.

Selenium Edit

Selenium is probably not essential for flowering plants, but it can be beneficial it can stimulate plant growth, improve tolerance of oxidative stress, and increase resistance to pathogens and herbivory. [27]

Mobile Edit

Nitrogen is transported via the xylem from the roots to the leaf canopy as nitrate ions, or in an organic form, such as amino acids or amides. Nitrogen can also be transported in the phloem sap as amides, amino acids and ureides it is therefore mobile within the plant, and the older leaves exhibit chlorosis and necrosis earlier than the younger leaves. [6] [10] Because phosphorus is a mobile nutrient, older leaves will show the first signs of deficiency. Magnesium is very mobile in plants, and, like potassium, when deficient is translocated from older to younger tissues, so that signs of deficiency appear first on the oldest tissues and then spread progressively to younger tissues.

Immobile Edit

Because calcium is phloem immobile, calcium deficiency can be seen in new growth. When developing tissues are forced to rely on the xylem, calcium is supplied by transpiration only.

Boron is not relocatable in the plant via the phloem. It must be supplied to the growing parts via the xylem. Foliar sprays affect only those parts sprayed, which may be insufficient for the fastest growing parts, and is very temporary. [ citation needed ]

In plants, sulfur cannot be mobilized from older leaves for new growth, so deficiency symptoms are seen in the youngest tissues first. [28] Symptoms of deficiency include yellowing of leaves and stunted growth. [29]

Symptoms Edit

The effect of a nutrient deficiency can vary from a subtle depression of growth rate to obvious stunting, deformity, discoloration, distress, and even death. Visual symptoms distinctive enough to be useful in identifying a deficiency are rare. Most deficiencies are multiple and moderate. However, while a deficiency is seldom that of a single nutrient, nitrogen is commonly the nutrient in shortest supply.

Chlorosis of foliage is not always due to mineral nutrient deficiency. Solarization can produce superficially similar effects, though mineral deficiency tends to cause premature defoliation, whereas solarization does not, nor does solarization depress nitrogen concentration. [30]

Macronutrients Edit

Nitrogen deficiency most often results in stunted growth, slow growth, and chlorosis. Nitrogen deficient plants will also exhibit a purple appearance on the stems, petioles and underside of leaves from an accumulation of anthocyanin pigments. [6]

Phosphorus deficiency can produce symptoms similar to those of nitrogen deficiency, [31] characterized by an intense green coloration or reddening in leaves due to lack of chlorophyll. If the plant is experiencing high phosphorus deficiencies the leaves may become denatured and show signs of death. Occasionally the leaves may appear purple from an accumulation of anthocyanin. As noted by Russel: [14] “Phosphate deficiency differs from nitrogen deficiency in being extremely difficult to diagnose, and crops can be suffering from extreme starvation without there being any obvious signs that lack of phosphate is the cause”. Russell's observation applies to at least some coniferous seedlings, but Benzian [32] found that although response to phosphorus in very acid forest tree nurseries in England was consistently high, no species (including Sitka spruce) showed any visible symptom of deficiency other than a slight lack of lustre. Phosphorus levels have to be exceedingly low before visible symptoms appear in such seedlings. In sand culture at 0 ppm phosphorus, white spruce seedlings were very small and tinted deep purple at 0.62 ppm, only the smallest seedlings were deep purple at 6.2 ppm, the seedlings were of good size and color. [33] [34]

The root system is less effective without a continuous supply of calcium to newly developing cells. Even short term disruptions in calcium supply can disrupt biological functions and root function. [35] A common symptom of calcium deficiency in leaves is the curling of the leaf towards the veins or center of the leaf. Many times this can also have a blackened appearance. [36] The tips of the leaves may appear burned and cracking may occur in some calcium deficient crops if they experience a sudden increase in humidity. [18] Calcium deficiency may arise in tissues that are fed by the phloem, causing blossom end rot in watermelons, peppers and tomatoes, empty peanut pods and bitter pits in apples. In enclosed tissues, calcium deficiency can cause celery black heart and "brown heart" in greens like escarole. [37]

Researchers found that partial deficiencies of K or P did not change the fatty acid composition of phosphatidyl choline in Brassica napus L. plants. Calcium deficiency did, on the other hand, lead to a marked decline of polyunsaturated compounds that would be expected to have negative impacts for integrity of the plant membrane, that could effect some properties like its permeability, and is needed for the ion uptake activity of the root membranes. [38]

Potassium deficiency may cause necrosis or interveinal chlorosis. Deficiency may result in higher risk of pathogens, wilting, chlorosis, brown spotting, and higher chances of damage from frost and heat. When potassium is moderately deficient, the effects first appear in the older tissues, and from there progress towards the growing points. Acute deficiency severely affects growing points, and die-back commonly occurs. Symptoms of potassium deficiency in white spruce include: browning and death of needles (chlorosis) reduced growth in height and diameter impaired retention of needles and reduced needle length. [39]

Micronutrients Edit

Mo deficiency is usually found on older growth. Fe, Mn and Cu effect new growth, causing green or yellow veins, Zn ca effect old and new leaves, and B will be seem on terminal buds. A plant with zinc deficiency may have leaves on top of each other due to reduced internodal expansion. [40]

Zinc is the most widely deficient micronutrient for industrial crop cultivation, followed by boron. Acidifying N fertilizers create micro-sites around the granule that keep micronutrient cations soluble for longer in alkaline soils, but high concentrations of P or C may negate these effects.

Boron deficiencies effecting seed yields and pollen fertility are common in laterite soils. [41] Boron is essential for the proper forming and strengthening of cell walls. Lack of boron results in short thick cells producing stunted fruiting bodies and roots. Deficiency results in the death of the terminal growing points and stunted growth. [ citation needed ] Inadequate amounts of boron affect many agricultural crops, legume forage crops most strongly. [ citation needed ] Boron deficiencies can be detected by analysis of plant material to apply a correction before the obvious symptoms appear, after which it is too late to prevent crop loss. Strawberries deficient in boron will produce lumpy fruit apricots will not blossom or, if they do, will not fruit or will drop their fruit depending on the level of boron deficit. Broadcast of boron supplements is effective and long term a foliar spray is immediate but must be repeated. [ citation needed ]

Boron concentration in soil water solution higher than one ppm is toxic to most plants. Toxic concentrations within plants are 10 to 50 ppm for small grains and 200 ppm in boron-tolerant crops such as sugar beets, rutabaga, cucumbers, and conifers. Toxic soil conditions are generally limited to arid regions or can be caused by underground borax deposits in contact with water or volcanic gases dissolved in percolating water. [ citation needed ]

Nitrogen fixation Edit

There is an abundant supply of nitrogen in the earth's atmosphere — N2 gas comprises nearly 79% of air. However, N2 is unavailable for use by most organisms because there is a triple bond between the two nitrogen atoms in the molecule, making it almost inert. In order for nitrogen to be used for growth it must be “fixed” (combined) in the form of ammonium (NH +
4 ) or nitrate (NO −
3 ) ions. The weathering of rocks releases these ions so slowly that it has a negligible effect on the availability of fixed nitrogen. Therefore, nitrogen is often the limiting factor for growth and biomass production in all environments where there is a suitable climate and availability of water to support life.

Microorganisms have a central role in almost all aspects of nitrogen availability, and therefore for life support on earth. Some bacteria can convert N2 into ammonia by the process termed nitrogen fixation these bacteria are either free-living or form symbiotic associations with plants or other organisms (e.g., termites, protozoa), while other bacteria bring about transformations of ammonia to nitrate, and of nitrate to N2 or other nitrogen gases. Many bacteria and fungi degrade organic matter, releasing fixed nitrogen for reuse by other organisms. All these processes contribute to the nitrogen cycle.

Nitrogen enters the plant largely through the roots. A “pool” of soluble nitrogen accumulates. Its composition within a species varies widely depending on several factors, including day length, time of day, night temperatures, nutrient deficiencies, and nutrient imbalance. Short day length promotes asparagine formation, whereas glutamine is produced under long day regimes. Darkness favors protein breakdown accompanied by high asparagine accumulation. Night temperature modifies the effects due to night length, and soluble nitrogen tends to accumulate owing to retarded synthesis and breakdown of proteins. Low night temperature conserves glutamine high night temperature increases accumulation of asparagine because of breakdown. Deficiency of K accentuates differences between long- and short-day plants. The pool of soluble nitrogen is much smaller than in well-nourished plants when N and P are deficient since uptake of nitrate and further reduction and conversion of N to organic forms is restricted more than is protein synthesis. Deficiencies of Ca, K, and S affect the conversion of organic N to protein more than uptake and reduction. The size of the pool of soluble N is no guide per se to growth rate, but the size of the pool in relation to total N might be a useful ratio in this regard. Nitrogen availability in the rooting medium also affects the size and structure of tracheids formed in the long lateral roots of white spruce (Krasowski and Owens 1999). [42]

Root environment Edit

Mycorrhiza Edit

Phosphorus is most commonly found in the soil in the form of polyprotic phosphoric acid (H3PO4), but is taken up most readily in the form of H2PO −
4 . Phosphorus is available to plants in limited quantities in most soils because it is released very slowly from insoluble phosphates and is rapidly fixed once again. Under most environmental conditions it is the element that limits growth because of this constriction and due to its high demand by plants and microorganisms. Plants can increase phosphorus uptake by a mutualism with mycorrhiza. [6] On some soils, the phosphorus nutrition of some conifers, including the spruces, depends on the ability of mycorrhizae to take up, and make soil phosphorus available to the tree, hitherto unobtainable to the non-mycorrhizal root. Seedling white spruce, greenhouse-grown in sand testing negative for phosphorus, were very small and purple for many months until spontaneous mycorrhizal inoculation, the effect of which was manifested by a greening of foliage and the development of vigorous shoot growth.

Root temperature Edit

When soil-potassium levels are high, plants take up more potassium than needed for healthy growth. The term luxury consumption has been applied to this. Potassium intake increases with root temperature and depresses calcium uptake. [43] Calcium to boron ratio must be maintained in a narrow range for normal plant growth. Lack of boron causes failure of calcium metabolism which produces hollow heart in beets and peanuts. [ citation needed ]

Nutrient interactions Edit

Calcium and magnesium inhibit the uptake of trace metals. Copper and zinc mutually reduce uptake of each other. Zinc also effects iron levels of plants. These interactions are dependent on species and growing conditions. For example, for clover, lettuce and red beet plants nearing toxic levels of zinc, copper and nickel, these three elements increased the toxicity of the others in a positive relationship. In barley positive interaction was observed between copper and zinc, while in French beans the positive interaction occurred between nickel and zinc. Other researchers have studied the synergistic and antagonistic effects of soil conditions on lead, zinc, cadmium and copper in radish plants to develop predictive indicators for uptake like soil pH. [44]

Calcium absorption is increased by water-soluble phosphate fertilizers, and is used when potassium and potash fertilizers decrease the uptake of phosphorus, magnesium and calcium. For these reasons, imbalanced application of potassium fertilizers can markedly decrease crop yields. [35]

Solubility and soil pH Edit

Boron is available to plants over a range of pH, from 5.0 to 7.5. Boron is absorbed by plants in the form of the anion BO 3−
3 . It is available to plants in moderately soluble mineral forms of Ca, Mg and Na borates and the highly soluble form of organic compounds. It is mobile in the soil, hence, it is prone to leaching. Leaching removes substantial amounts of boron in sandy soil, but little in fine silt or clay soil. Boron's fixation to those minerals at high pH can render boron unavailable, while low pH frees the fixed boron, leaving it prone to leaching in wet climates. It precipitates with other minerals in the form of borax in which form it was first used over 400 years ago as a soil supplement. Decomposition of organic material causes boron to be deposited in the topmost soil layer. When soil dries it can cause a precipitous drop in the availability of boron to plants as the plants cannot draw nutrients from that desiccated layer. Hence, boron deficiency diseases appear in dry weather. [ citation needed ]

Most of the nitrogen taken up by plants is from the soil in the forms of NO −
3 , although in acid environments such as boreal forests where nitrification is less likely to occur, ammonium NH +
4 is more likely to be the dominating source of nitrogen. [45] Amino acids and proteins can only be built from NH +
4 , so NO −
3 must be reduced.

Fe and Mn become oxidized and are highly unavailable in acidic soils. [ citation needed ]

Nutrient status (mineral nutrient and trace element composition, also called ionome and nutrient profile) of plants are commonly portrayed by tissue elementary analysis. Interpretation of the results of such studies, however, has been controversial. [46] During recent decades the nearly two-century-old “law of minimum” or “Liebig's law” (that states that plant growth is controlled not by the total amount of resources available, but by the scarcest resource) has been replaced by several mathematical approaches thatl use different models in order to take the interactions between the individual nutrients into account. [ citation needed ]

Later developments in this field were based on the fact that the nutrient elements (and compounds) do not act independently from each other [46] Baxter, 2015, [47] because there may be direct chemical interactions between them or they may influence each other's uptake, translocation, and biological action via a number of mechanisms [46] as exemplified [ how? ] for the case of ammonia. [48]

Fertilizers Edit

Boron is highly soluble in the form of borax or boric acid and is too easily leached from soil making these forms unsuitable for use as a fertilizer. Calcium borate is less soluble and can be made from sodium tetraborate. Boron is often applied to fields as a contaminant in other soil amendments but is not generally adequate to make up the rate of loss by cropping. The rates of application of borate to produce an adequate alfalfa crop range from 15 pounds per acre for a sandy-silt, acidic soil of low organic matter, to 60 pounds per acre for a soil with high organic matter, high cation exchange capacity and high pH. Application rates should be limited to a few pounds per acre in a test plot to determine if boron is needed generally. Otherwise, testing for boron levels in plant material is required to determine remedies. Excess boron can be removed by irrigation and assisted by application of elemental sulfur to lower the pH and increase boron solubility. Foliar sprays are used on fruit crop trees in soils of high alkalinity. [ citation needed ]

Selenium is, however, an essential mineral element for animal (including human) nutrition and selenium deficiencies are known to occur when food or animal feed is grown on selenium-deficient soils. The use of inorganic selenium fertilizers can increase selenium concentrations in edible crops and animal diets thereby improving animal health. [27]

It is useful to apply a high phosphorus content fertilizer, such as bone meal, to perennials to help with successful root formation. [6]

Hydroponics Edit

Hydroponics is a method for growing plants in a water-nutrient solution without the use of nutrient-rich soil. It allows researchers and home gardeners to grow their plants in a controlled environment. The most common artificial nutrient solution is the Hoagland solution, developed by D. R. Hoagland and W. C. Snyder in 1933. The solution (known as A-Z solution a and b) consists of all the essential nutrients in the correct proportions necessary for most plant growth. [6] An aerator is used to prevent an anoxic event or hypoxia. Hypoxia can affect nutrient uptake of a plant because, without oxygen present, respiration becomes inhibited within the root cells. The nutrient film technique is a hydroponic technique in which the roots are not fully submerged. This allows for adequate aeration of the roots, while a "film" thin layer of nutrient-rich water is pumped through the system to provide nutrients and water to the plant.

Hormones vs Co2 - Hormones Cheaper Potentially Yeild the Same!

The hormones are not magic. All these hormones are produced naturally by the plant. the amounts produced by the plant are genetically determined. THIS IS WHERE WE MAKE OUR IMPACT. Ever get a clone/plant that just refuses to grow like the other plants and stays a "dwarf" with misformed leaves, yet the other sister plants are thriving? Chances are the dwarf is not kicking out the hormones for one reason or another. adding hormones to your growing methods allows you to enhance the plant even beyond it's genetic capabilities. The stems are thicker and stronger, leaves are bigger and greener, roots are healthier and more lush and the flowers are bigger, heavier and more resinous. But. and it's a BIG but. If you can't grow excellent plants without hormones, then adding hormones will make things worse.
Only common sense. You are stimulating the plants to "kick it up a notch" on the growing scale. The plant will need good growing support. nutrients, light, etc, etc.
It's the same sort of thing if you are using CO2 supplementation. You need to have your growing program working @max on other levels first. But In my mind can be CHEAPER and just as effective as Co2 Supp`s. If you had both well. now were talkin.


Plant Hormone &#8212 an endogenous regulator. To be a hormone, a chemical must be produced within the plant, transported from a site of production to a site of action, and be active in small amounts.

Probably the best known of the plant hormones. It's produced by the plants tips and is responsible for the plant growth. The problem with GA3, is that most growth is in the form of "stretching" which isn't always diserable, so except for seeds and clones.

GA3 has some other uses as well. You can intiate male fowers on a female plant but using high doses every day for several days, you can also induce female flowers earlier and yield bigger flowers .

The gibberellins are widespread throughout the plant kingdom, and more than 75 have been isolated, to date. Rather than giving each a specific name, the compounds are numbered&#8212for example, GA1, GA2, and so on. Gibberellic acid three (GA3) is the most widespread and most thoroughly studied. The gibberellins are especially abundant in seeds and young shoots where they control stem elongation by stimulating both cell division and elongation (auxin stimulates only cell elongation). The gibberellins are carried by the xylem and phloem. Numerous effects have been cataloged that involve about 15 or fewer of the gibberellic acids. The greater number with no known effects apparently are precursors to the active ones.

I know there has been experimentation with GA3 sprayed on genetically dwarf plants stimulates elongation of the dwarf plants to normal heights. Normal-height plants sprayed with GA3 become giants. like addicott study on next post.

I Found a botinist that germinationg 2000yr old exstinct SEEDS into plants with this hormone.

although the results of gibberellic acid (GA3) applications vary depending on many factors, including the type of plants its applied to. In one study of persimmon yield (1) it was found that applications of 15 to 30 PPM increased yields by 50% to 400%. In another study (2) it was even found that if gibberellic acid is applied to a plant the next generation of the plant would also benefit from faster flowering and increased height. In another study of walnut trees it was found that applications of gibbarellic acid (GA3) increased growth by 567% (3).
1) Increasing Persimmon Yields With Gibberellic Acid []
2) Generations Living with Gibberellic Acid []
3) Gibberellic Acid for Fruit Set and Seed Germination []

A study on persimmons 1 increased yield by at least 50%. This was done with a foliar spray of 15 to 30 ppm when the plants where at full bloom.

retail names:
Gibberellic Acid (GA3),

Functions of Gibberellins

  • Stimulate stem elongation by stimulating cell division and elongation.
  • Stimulates bolting/flowering in response to long days.
  • Breaks seed dormancy in some plants which require stratification or light to induce germination.
  • Stimulates enzyme production (a-amylase) in germinating cereal grains for mobilization of seed reserves.
  • Induces maleness in dioecious flowers (sex expression).
  • Can cause parthenocarpic (seedless) fruit development.
  • Can delay senescence in leaves and citrus fruits.

Leaf trichomes protect plants from attack by insect herbivores and are often induced following damage. Hormonal regulation of this plant induction response has not been previously studied. In a series of experiments, we addressed the effects of artificial damage, jasmonic acid, salicylic acid, and gibberellin on induction of trichomes in Arabidopsis. Artificial damage and jasmonic acid caused significant increases in trichome production of leaves. The jar1-1 mutant exhibited normal trichome induction following treatment with jasmonic acid, suggesting that adenylation of jasmonic acid is not necessary. Salicylic acid had a negative effect on trichome production and consistently reduced the effect of jasmonic acid, suggesting negative cross-talk between the jasmonate and salicylate-dependent defense pathways. Interestingly, the effect of salicylic acid persisted in the nim1-1 mutant, suggesting that the Npr1/Nim1 gene is not downstream of salicylic acid in the negative regulation of trichome production. Last, we found that gibberellin and jasmonic acid had a synergistic effect on the induction of trichomes, suggesting important interactions between these two compounds.

Brassinolide is a naturally occuring plant steroid it is normally found in plants. In fact, it was first discovered HORMONE in plants. Brassinolide has been found to be an important element for plant growth. Foliar spray about every three weeks with a final spray just as change the lights for flowering. It will increase a plants resistance to stress (cold, drought, too high a salt content), it helps the plant locate light, it strengthens a plants resistance to disease. It will also stimulate a plant to grow it's overall root mass. The overall effect is that the plant will be much healthier, stronger and thus the yield will be better. Estimate that the effect is about a 50% better yield than the untreated plants.
A study concluded that Brassinolide increased the growth of the primary root by 90%.
Another study concluded that a 0.0001 PPM application for 8 hours has the best results for the creation of some roots.

This is actually a growth inhibitor. It is sold in Hydro stores in pre-made solutions under various brand names. The idea is that it will stop the plant growth when it's time to start flowering. Not only does this control the final height (useful if you have a low ceiling problem), but also the plant will start to allocate it's growth resources into bud growth sooner. . The growth is halted (actually, some growth still occurs). the effect you see is that bud size that were usually about 5 weeks old are now bud size at 3 weeks. This gives you larger early buds and as you know, you can only build from there. The hit the plants with the Benzylaminopurine and the bud growth takes off.
Abscisic acid - ESSENTIALLY STOPS GROWTH also inhibitor.
Abscisic acid (ABA), despite its name, does not initiate abscission (shedding) , although in the 1960s when it was named botanists thought that it did. It is synthesized in plastids from carotenoids and diffuses in all directions through vascular tissues and parenchyma. Its principal effect is inhibition of cell growth. ABA increases in developing seeds and promotes dormancy. If leaves experience water stress, ABA amounts increase immediately, causing the stomata to close.

Functions of Abscisic Acid

  • Stimulates the closure of stomata (water stress brings about an increase in ABA synthesis).
  • Inhibits shoot growth but will not have as much affect on roots or may even promote growth of roots.
  • Induces seeds to synthesize storage proteins.
  • Inhibits the affect of gibberellins on stimulating de novo synthesis of a-amylase.
  • Has some effect on induction and maintanance of dormancy.
  • Induces gene transcription especially for proteinase inhibitors in response to wounding which may explain an apparent role in pathogen defense

Synthetic auxins are extensively used as herbicides, the most widely known being 2,4-D and the notorious 2,4,5-T, which were used in a 1:1 combination as Agent Orange during the Vietnam War and sprayed over the Vietnam forests as a defoliant.

Chemists have synthesized several inexpensive compounds similar in structure to IAA. Synthetic auxins, like naphthalene acetic acid, of NAA, are used extensively to promote root formation on stem and leaf cuttings. Gardeners often spray auxins on tomato plants to increase the number of fruits on each plant. When NAA is sprayed on young fruits of apple and olive trees, some of the fruits drop off so that the remaining fruits grow larger. When NAA is sprayed directly on maturing fruits, such as apples, pears and citrus fruits, several weeks before they are ready to be picked NAA prevents the fruits from dropping off the trees before they are mature. The fact that auxins can have opposite effects, causing fruit to drop or preventing fruit from dropping, illustrates an important point. The effects of a hormone on a plant often depend on the stage of the plant's development.
NAA is used to prevent the undesirable sprouting of stems from the base of ornamental trees. As previously discussed, stems contain a lateral bud at the base of each leaf. IN many stems, these buds fail to sprout as long as the plant's shoot tip is still intact. The inhibition of lateral buds by the presence of the shoot tip is called apical dominance. If the shoot tip of a plant is removed, the lateral buds begin to grow. If IAA or NAA is applied to the cut tip of the stem, the lateral buds remain dormant. This adaptation is manipulated to cultivate beautiful ornamental trees. NAA is used commercially to prevent buds from sprouting on potatoes during storage.
Another important synthetic auxin is 2,4-D, which is an herbicide, or weed killer. It selectively kills dicots, such as dandelions and pigweed, without injuring monocots, such as lawn grasses and cereal crops. Given our major dependence on cereals for food 2,4-D has been of great value to agriculture. A mixture of 2, 4-D and another auxin, called Agent Orange, was used to destroy foliage in the jungles of Vietnam. A non-auxin contaminant in Agent Orange has caused severe health problems in many people who were exposed to it.

  • Stimulates cell elongation
  • Stimulates cell division in the cambium and, in combination with cytokinins in tissue culture
  • Stimulates differentiation of phloem and xylem
  • Stimulates root initiation on stem cuttings and lateral root development in tissue culture
  • Mediates the tropistic response of bending in response to gravity and light
  • The auxin supply from the apical bud suppresses growth of lateral buds
  • Delays leaf senescence
  • Can inhibit or promote (via ethylene stimulation) leaf and fruit abscission
  • Can induce fruit setting and growth in some plants
  • Involved in assimilate movement toward auxin possibly by an effect on phloem transport
  • Delays fruit ripening
  • Promotes flowering in Bromeliads
  • Stimulates growth of flower parts
  • Promotes (via ethylene production) femaleness in dioecious flowers
  • Stimulates the production of ethylene at high concentrations

ORGANS are the relating factor:
Growth and division of plant cells together result in growth of tissue, and specific tissue growth contributes to the development of plant organs. Growth of cells contributes to the plant's size, but uneven localized growth produces bending, turning and directionalization of organs- for example, stems turning toward light sources ( phototropism ), roots growing in response to gravity (gravitropism), ETC
Organization of the plant
As auxins contribute to organ shaping, they are also fundamentally required for proper development of the plant itself. Without hormonal regulation and organization, plants would be merely proliferating heaps of similar cells. Auxin employment begins in the embryo of the plant, where directional distribution of auxin ushers in subsequent growth and development of primary growth poles, then forms buds of future organs. Throughout the plant's life, auxin helps the plant maintain the polarity of growth and recognize where it has its branches (or any organ) connected.
A number of other effects of auxin are described. (Indoleacetic acid was called heteroauxin in the older literature. The hypothetical auxin a and auxin b have never been isolated and are now generally considered invalid.)
Indole-3-butyric acid (IBA) - rooting
IBA is a plant hormone in the auxin family and is an ingredient in many commercial plant rooting horticultural products.
For use as such, it should be dissolved in about 75% (or purer) alcohol (as IBA does not dissolve in water), until a concentration from between 10,000 ppm to 50,000 ppm is achieved - this solution should then be diluted to the required concentration using distilled water. The solution should be kept in a cool, dark place for best results.
This compound had been thought to be strictly synthetic however, it was reported that the compound was isolated from leaves and seeds of maize and other species.
Indole-3-acetic acid (IAA) is the most abundant naturally occurring auxin. Plants produce active IAA both by de novo synthesis and by releasing IAA from conjugates. This review emphasizes recent genetic experiments and complementary biochemical analyses that are beginning to unravel the complexities of IAA biosynthesis in plants. Multiple pathways exist for de novo IAA synthesis in plants, and a number of plant enzymes can liberate IAA from conjugates. This multiplicity has contributed to the current situation in which no pathway of IAA biosynthesis in plants has been unequivocally established. Genetic and biochemical experiments have demonstrated both tryptophan-dependent and tryptophan-independent routes of IAA biosynthesis. The recent application of precise and sensitive methods for quantitation of IAA and its metabolites to plant mutants disrupted in various aspects of IAA regulation is beginning to elucidate the multiple pathways that control IAA levels in the plant.

Antiauxin &#8212 (synonyms: auxin inhibitor, auxin competitor, auxin antagonist). A compound which competitively inhibits (in the biochemical sense) the action of auxin.
Continued research on auxin has made it apparent that auxin physiology is much more complicated than it first seemed. Auxin appears to be present in all living parts of the plant, mature as well as immature. The amounts present are effected by at least three general processes: auxin production, auxin transport, and auxin inactivation. Many of the early investigations did not recognise the existence of these three processes and their results must be re-evaluated. For example, many studies of auxin transport did not take into account the probability of considerable auxin inactivation during the course of transport. Auxin is produced principally in young tissues, but can also be produced by mature tissues. The amino acid tryptophan, a common constituent of proteins, is the precursor of auxin, but the precise chemical steps of its conversion to auxin are not yet settled. The transport of auxin can be through the parenchyma, as it is in the oat coleoptile, but in more mature tissues transport is largely in the phloem. In the coleoptile transport is correlated with the streaming of protoplasm. Auxin inactivation is accomplished by an oxidative enzyme which can function either in the dark or under the influence of light. Mature tissues have relatively high auxin-inactivating capacities. In addition to these general processes other factors, still obscure, also influence the auxin in tissues. The interaction of these processes and factors determines the level of auxin which is available to influence growth and morphogenesis
1-Naphthaleneacetic Acid (NAA),
The effects of 1-naphthaleneacetic acid (NAA) applied at various levels and times on yield, seed index, protein and oil content and fatty acid compositions of cotton plants seeds were studied. NAA increased the seed yield/plant and the seed, protein, and oil yields/ha compared to the control. A level of 20 ppm proved best for yield. Most NAA treatments significantly increased the seed index, but only slight increases in seed protein content were recorded.


1-Naphthaleneacetic Acid (NAA), Indole-3-acetic Acid (IAA), Indole-3-butyric Acid (IBA), Indole-3-Propionic Acid (IPA), (+)-cis,trans-Abscisic Acid (ABA)

Named because of their discovered role in cell division (cytokinesis), the cytokinins have a molecular structure similar to adenine. Naturally occurring zeatin, isolated first from corn ( Zea mays), is the most active of the cytokinins. Cytokinins are found in sites of active cell division in plants&#8212for example, in root tips, seeds, fruits, and leaves. They are transported in the xylem and work in the presence of auxin to promote cell division. Differing cytokinin:auxin ratios change the nature of organogenesis. If kinetin is high and auxin low, shoots are formed if kinetin is low and auxin high, roots are formed. Lateral bud development, which is retarded by auxin, is promoted by cytokinins. Cytokinins also delay the senescence of leaves and promote the expansion of cotyledons.
There are two types of cytokinins: adenine-type cytokinins represented by kinetin, zeatin and 6-benzylaminopurine (mentioned), as well as phenylurea-type cytokinins like diphenylurea or thidiazuron (TDZ). The adenine-type cytokinins are synthesised in stems, leaves and roots, which is the major site.Cambiumand possibly other actively dividing tissues are also sites of cytokinin biosynthesis.There is no evidence that the phenylurea cytokinins occur naturally in plant tissues. Cytokinins are involved in both local and long distance signalling, the latter of which involves the same in planta transport mechanism as used for transport of purines and nucleosides.
retail names:
6-Furfurylaminopurine (Kinetin), Para-Aminobenzoic Acid, trans-Zeatin, Thidiazuron (TDZ), Zeatin Riboside

  • Stimulates cell division.
  • Stimulates morphogenesis (shoot initiation/bud formation) in tissue culture.
  • Stimulates the growth of lateral buds-release of apical dominance.
  • Stimulates leaf expansion resulting from cell enlargement.
  • May enhance stomatal opening in some species.
  • Promotes the conversion of etioplasts into chloroplasts via stimulation of chlorophyll synthesis.

Effects are Latrial growth giving it thicker and stronger stems, healthier and larger leaves (more surface area to capture light) at 300 ppm. Plant will have more branches, foliar spray of 2000ppm. The advantage is that you don't need to pinch of the plants growing tip (thus decreasing the gibberrelins), the plant stays healthy and doesn't stop growing to repair the tip. But dosent gain hieght.

Another big bonus. If you spray MJ with 300ppm at the end of the 4th week of flowring there is a dramatic increase in bud growth. Combined with the earlier spraying of Brassinlide , the end result is outstanding in terms of quality and yield.

6-Benzylaminopurine, benzyl adenine or BAP is a first-generation synthetic cytokinin which elicits plant growth and development responses, setting blossoms and stimulating fruit richness by stimulating cell division. It is an inhibitor of respiratory kinase in plants, and increases post-harvest life of green vegetables.
6-benzylaminopurine was first synthetized and tested in the laboratories of plant physiologist Folke K. Skoog.
retail names:
6-(y,y-dimethylallylamino)purine (2ip). 6-Benzylaminopurine (6-BA, BA, BAP), 2-carboxylphenyl 3-phenyIpropane 1,3-dione (CPD),

Ethylene is a simple gaseous hydrocarbon produced from an amino acid and appears in most plant tissues in large amounts when they are stressed. It diffuses from its site of origin into the air and affects surrounding plants as well. Large amounts ordinarily are produced by roots, senescing flowers, ripening fruits, and the apical meristem of shoots. Auxin increases ethylene production, as does ethylene itself&#8212small amounts of ethylene initiate copious production of still more. Ethylene stimulates the ripening of fruit and initiates abscission of fruits and leaves. (this is really intresting could be whats in LAFEMME ) In monoecious plants (those with separate male and female flowers borne on the same plant), gibberellins and ethylene concentrations determine the sex of the flowers: Flower buds exposed to high concentrations of ethylene produce carpellate flowers, while gibberellins induce staminate ones.

WIKIPEDIA DEF:Ethylene is produced at a faster rate in rapidly growing and dividing cells, especially in darkness. New growth and newly-germinated seedlings produce more ethylene than can escape the plant, which leads to elevated amounts of ethylene, inhibiting leaf expansion. As the new shoot is exposed to light, reactions by photochrome in the plant's cells produce a signal for ethylene production to decrease, allowing leaf expansion. Ethylene affects cell growth and cell shape when a growing shoot hits an obstacle while underground, ethylene production greatly increases, preventing cell elongation and causing the stem to swell. The resulting thicker stem can exert more pressure against the object impeding its path to the surface. If the shoot does not reach the surface and the ethylene stimulus becomes prolonged, it affects the stems natural geotropic response, which is to grow upright, allowing it to grow around an object. Studies seem to indicate that ethylene affects stem diameter and height: When stems of trees are subjected to wind, causing lateral stress, greater ethylene production occurs, resulting in thicker, more sturdy tree trunks and branches. Ethylene affects fruit-ripening: Normally, when the seeds are mature, ethylene production increases and builds-up within the fruit, resulting in a climacteric event just before seed dispersal. The nuclear protein ETHYLENE INSENSITIVE2 (EIN2) is regulated by ethylene production, and, in turn, regulates other hormones including ABA and stress hormones

  • The hormone ethylene is responsible for the ripening of fruits. Unlike the other four classes of plant hormones, ethylene is a gas at room temperature. Ethylene gas diffuses easily through the air from one plant to another. The saying "One bad apple spoils the barrel" has its basis in the effects of ethylene gas. One rotting apple will produce ethylene gas, which stimulates nearby apples to ripen and eventually spoil because of over ripening.
    Ethylene is usually applied in a solution of ethephon, a synthetic chemical that breaks down and releases ethylene gas. It is used to ripen bananas, honeydew melons and tomatoes. Oranges, lemons, and grapefruits often remain green when they are ripe. Although the fruit tastes good, consumers often will not buy them, because oranges are supposed to be orange, right? The application of ethylene to green citrus fruit causes the development of desirable citrus colors, such as orange and yellow. In some plant species, ethylene promotes abscission, which is the detachment of leaves, flowers, or fruits from a plant. Cherries and walnuts are harvested with mechanical tree shakers. Ethylene treatment increases the number of fruits that fall to the ground when the trees are shaken. Leaf abscission is also an adaptive advantage for the plant. Dead, damaged or infected leaves drop to the ground rather than shading healthy leaves or spreading disease. The plant can minimize water loss in the winter, when the water in the plant is often frozen.

Thiamin or thiamine , also known as vitamin B1 and aneurine hydrochloride, is the term for a family of molecules sharing a common structural feature responsible for its activity as a vitamin. It is one of the B vitamins. Its most common form is a colorless chemical compound with a chemical formula C 12 H 17 N 4 O S . This form of thiamin is soluble in water, methanol, and glycerol and practically insoluble in acetone, ether, chloroform, and benzene. Another form of thiamin known as TTFD has different solubility properties and belongs to a family of molecules often referred to as fat-soluble thiamins. Thiamin decomposes if heated. Its chemical structure contains a pyrimidine ring and a thiazole ring

is one of the compounds that can be called vitamin B6, along with Pyridoxal and Pyridoxamine. It differs from pyridoxamine by the substituent at the '4' position. It is often used as 'pyridoxine hydrochloride'.
Water soluble
B vitamins
B1 (Thiamine) · B2 (Riboflavin) · B3 (Niacin, Nicotinamide) · B5 (Pantothenic acid, Dexpanthenol, Pantethine) · B6 (Pyridoxine, Pyridoxal phosphate, Pyridoxamine)
B7 (Biotin) · B9 (Folic acid, Folinic acid) · B12 (Cyanocobalamin, Hydroxocobalamin, Methylcobalamin, Cobamamide)
C (Ascorbic acid) · Choline


Point: If you add just Co2 (CARBON) and not understand & APPLYING the above. your not yeilding your max potetial ??


Well-Known Member

to fully understand. I would never have dwarf probs, sick plants, always grow beyond its parents, yeild better every time. etc


have seen around though.. should not be hard
Also use natural forms such as willow water, asprin etc

-Measure the ripening of unripe BUD induced by the plant hormone ethylene, with increased light 19/5 example
-Determine if plant size could be increased by manipulating / regulating 6-ben,IAA,GA3 hormone,ETC
-What is the role of hormones in synchronizing ripening?
-The Effect of same Hormones on different strains
-The effect of different concentrations of the plant growth substance IAA and gibberellic acid on the growth of roots and shoots
-Compare rate of plant growth using two different growth hormones
-The effect of estrogen on the growth of veg
-The effect of Rootone hormone on plant growth - which i thinks been cover by PANHEAD & fddblk < Root gel and some experiments > with GOOD results
-Effect of Different Concentrations of IAA on Root Initiation
-Simple experiments to explain the role of phytohormones in plants
-The effects of plant regulators (auxins and cytokinins) on different strains
-Abscisic acid for seed germination and enhancement of its catabolism by gibberellin
-Phase breakdown of naturally produced hormones and ballster exsisting

Basiclly Bolster all hormones adn consintrate our efforts with the major groups. auxins, gibberellins, ethylene, cytokinins, and abscisic acid.



Well-Known Member


Well-Known Member


Well-Known Member


Well-Known Member


Well-Known Member


Well-Known Member

By Frederick T. Addicott * ,
Fullbright Research Scholar, Department of Botany, Victoria University of Wellington

Growth Hormones : Gibberellins. The gibberellins produce effects on growth, particularly cell elongation, which are very similar to the effects of auxin, but they function in situations where auxin does not promote elongation. Although physiological and biochemical knowledge of them is still fragmentary, they are growth factors which are probably hormones and hence should be included here. The chemicals derive their name from the fungus Gibberella , from which they can be obtained. Immature seeds are also very rich sources.
One of the most interesting series of experiments with the gibberellins was conducted with a dwarf corn (maize). This particular mutant dwarf had been the subject of an intensive auxin study, and its auxin physiology was found to be completely normal. That is, auxin production, transport and inactivation were identical with those of normal corn, and applications of additional auxin did not affect its growth the plants never grew more than a few inches tall. However, weekly sprays of gibberellins stimulated the mutant to the normal rate of growth and practically normal appearance. The results of a similar experiment conducted several years earlier, which were at the time puzzling, can now be interpreted as due to gibberellins : an extract from immature bean seeds was applied to a bush variety of beans (Phaseolus) the stems then elongated in the manner characteristic of the tall varieties of beans. In other experiments, gibberellins sprayed on pasture grasses have induced abnormally rapid growth.
Another effect of gibberellins is in relation to both growth and flowering. Hyocyamus is one of the typical &#8216long-day plants&#8217. It grows as a rosette with its leaves clustered about the very short stem until it has been exposed to a period of cold followed by a period of long days. Then the stem rapidly elongates and produces flowers. It has been found that gibberellins can replace the cold treatment sprays followed by long days stimulate stem elongation with flowering.
Wound Hormone. Following an injury to a plant, the parenchyma cells underlying the injured area are stimulated to divide and form a protective callus. Under the stimulus, cells divide which would otherwise remain intact to the death of the plant. Early experiments showed that if the injured area is washed immediately, cell division is prevented this suggested that a hormone might be involved. Such a hormone was isolated by Bonner and English. Starting with 100 pounds of string beans they isolated a small amount of a chemical which they called traumatic acid (chemically, decene dicarboxylic acid) which is the wound hormone of beans. However, this compound does not stimulate cell division in other species. So there remain other chemicals yet to be identified as wound hormones.
Root Growth Hormones . Knowledge of root growth hormones has come largely from experiments with the culture of isolated roots. The repeated attempts to culture isolated tissues of plants were successful in 1933 with tomato roots and a culture medium consisting of sucrose, salts, and yeast extract. Yeast extract is a very complex mixture of chemicals and attention was immediately given to determination of the active components. These were soon found to be thiamin and pyridoxin which in small amounts (a few parts per million) could completely replace the yeast extract. Thus tomato roots, which in the field would live only a few months, have been kept growing in culture in a synthetic medium since soon after 1933. Thiamin and pyridoxin were first called growth factors, since their role in the intact plant was not known. However, Bonner showed that they are produced in leaves and transported downward to roots, thus establishing them as hormones.
Other experiments showed that niacin is a root growth factor, and is presumably also a root growth hormone. In various combinations thiamin, pyridoxin or niacin will support the indefinite growth of isolated roots of many species. For a few species other factors are required such as the amino acids glycine, lysine and arginine.
Although the roots of many plants will grow rapidly (at rates at least equal to the rates of roots on intact plants) and indefinitely in synthetic culture media, important problems still remain unsolved. One is the culture of isolated roots of monocotyledonous plants. In spite of numerous attempts, these have never been established in culture. Another is the development of the cambium , which has not been induced in roots of established
cultures. Further, branching of cultured roots is often abnormal. Thus the knowledge of root growth physiology is far from complete and much work lies ahead.
Experiments with root cultures brought to light an important interrelationship of vitamins and hormones. The chemicals thiamin, pyridoxin and niacin are vitamins , necessary in the diet of animals and other heterotrophs for normal growth and maintenance. In the green plant these same chemicals function in the physiological role of hormones. And within the cells of organisms they each function as a part of a vital enzyme. Thus the same chemical may function in any of three physiological roles: vitamin, hormone, enzyme.
Leaf Growth Hormone : Phyllocaline . In a search for hormones other than auxin Went performed an extensive series of grafting experiments. He worked with varieties of garden peas which differed markedly in their growth habits. The results showed, for example, that leaves of different varities differed in their ability to stimulate root growth. Similar differences among roots and buds were observed. Went postulated that these differences in growth were the result of differences in production of special hormones by the varieties. One of these postulated hormones was called phyllocaline . It is produced in cotyledons and mature leaves, and stimulates the growth of young leaves. This hormone was isolated and identified as adenine . Another property of adenine was later discovered tissue cultures of plant callus ordinarily grow indefinitely as an undifferentiated, or at best, slightly differentiated mass of cells. In the culture medium adenine stimulates the differentiation of leafy buds.
Adenine too has multiple physiological roles: It is a vitamin B for some organisms and within cells functions as a part of several enzymes and of the energy-storing phosphate compounds. Flowering Hormone: Florigen . Flowering is influenced by many factors including mineral and carbohydrate nutrition, temperature, photoperiod, and a postulated hormone, florigen. This hormone is produced in leaves (under particular conditions) and is transported to buds where it brings about the conversion of a vegetative stem apex to a reproductive stem apex (flower bud). Numerous experiments indicate its existence, but attempts to isolate florigen have not yet been successful. For further discussion of flowering see the recent article by Sussex.
Reproductive Hormones . In the lower plants a number of hormones influencing reproductive processes have been described, as well as nutritional factors which can be called reproductive vitamins .
One of the best known examples of reproductive hormones is in a heterothallic species of a water mould, Achlya , where Raper in extensive experiments found four hormones:
Growth Factors . Experiments have demonstrated growth factor requirements for many plant parts. Many, possibly all, of these growth factors are plant hormones, but present knowledge is too fragmentary in most cases to permit positive statements.
Pollen germination and tube growth factors. Pollen of some species will germinate and grow well in artificial media pollen of others will grow poorly or not at all. Stigmatic exudates are usually very stimulatory and presumably provide hormones required by the pollen. Chemicals which have been found to promote germination or tube growth of various species include: boric acid, manganous sulphate, ascorbic acid, aminobenzoic acid, indoleacetic acid, inositol, lactoflavin, guanine, pyridoxin, thiamin.

Growth factors of tissue and organ cultures . Since the successful establishment of root cultures, other organs and several types of tissues have been successfully cultured including embryos, shoots, and callus. Often successful culture has required the use of complex mixtures such as malt extract, young seed extracts, or coconut milk. The latter is a potent source of important growth factors its use has enabled the culture of very small embryos, but the active chemicals in coconut milk have not been identified. Growth factors which have been identified include: ascorbic acid, adenine, biotin, indoleacetic acid, niacin, pantothenic acid, thiamin . It is of interest to note that each of these is already known to have functions as a vitamin and/or hormone.

Growth Inhibiting Hormones . The discussion to this point has dealt with hormones and other factors which in the main promote growth and development. (A few of these, such as auxin , will under some conditions inhibit or retard growth.) In addition, there is now an increasing list of chemicals whose principal function appears to be the inhibition of growth. Since these chemicals are endogenous, often act at very low concentrations, and move from a site of production to a site of action, they should be considered hormones. Only seed germination inhibitors will be mentioned here knowledge of others is very fragmentary.
Germination inhibitors act variously: (a) to prevent premature seed germination (b) to extend the period of germination by permitting only a fraction of the seeds to germinate at any one time and (c) to suppress germination of competing species while permitting germination of a favoured species. Evenari has described over 120 inhibitors these are produced in fruit pulp, fruit coats, endosperm, seed coats, embryos, leaves, bulbs, and roots. Identified inhibitors include: hydrocyanic acid, ammonia, ethylene, mustard oils, aldehydes, alkaloids, essential oils, lactones, organic acids. It is of interest that an inhibitor can sometimes stimulate germination. Inhibition or stimulation may result from different concentrations, but sometimes one follows the other from the same concentration.
In a few decades the subject of plant hormones has expanded to a broad and amazingly complex field of plant physiology, at least equal in complexity to the field of animal hormones. This research received much of its initial impetus from Sachs' postulate that plant morphogenesus is regulated by specific organ-forming chemicals. Indeed, there is now much evidence on the effects of specific chemicals (or groups of chemicals). However, the impression should not remain that morphogenesis is regulated solely by such chemicals (that is, by hormones or vitamins). Temperature, light, water, mineral nutrients, foods, and other factors are also important in the development of plants and at times one or more of these factors may have a decisive influence on growth, acting either directly or through intermediate effects on plant hormones.

Get notified when we have news, courses, or events of interest to you.

By entering your email, you consent to receive communications from Penn State Extension. View our privacy policy.

Thank you for your submission!

Flower Trial Field Day


Amelanchier Diseases


Pruning Ornamental Plants

Guides and Publications

Improve Energy Efficiency in Greenhouses


Employee Landscape Training: Planting, Mulching, and Watering

Online Courses

The Impact of Salts on Plants and How to Reduce Plant Injury from Winter Salt Applications

Across the country, more than 22 million tons of road salt is used every year. In Massachusetts, the Department of Transportation (MassDOT) recommends one or more applications of salt at 240 lbs per lane mile after every snow fall to ensure the safety of those using the roadways.

The most commonly used salt for deicing roads is sodium chloride (rock salt) because it is inexpensive, effective and readily available. Despite the benefits of improving safety on roads, streets, sidewalks, driveways and parking lots, deicing salt can cause damage to landscape plants. Deicing salts can cause injury and contribute to the decline and death of landscape plants. However, an understanding of the impacts salts have on plants and salt application management strategies can help to protect plants or reduce plant injury due to salt.

How Salt Affects Plants

Salt damage occurs on plants when salt is deposited by spray from passing cars on stems and buds of deciduous woody plants and on stems, buds, leaves and needles of evergreen plants. Salt spray can cause salt burn on buds, leaves and small twigs. Salt spray can also cause damage by desiccating the bud scales, exposing tender tissues of the developing leaves and flowers. The unprotected developing leaves and flower buds dry out and are often killed by the cold winter wind. Many times, the damage is not evident until late winter or spring. Needle or leaf browning, bud death, and branch dieback on the side of the plant facing the road or sidewalk is a common sign of salt spray damage. Damage to deciduous plants is not seen until growth resumes in the spring.

Plants are also affected by dissolved salts in runoff water. Sodium and chloride ions separate when salts are dissolved in water. The dissolved sodium and chloride ions, in high concentrations, can displace other mineral nutrients in the soil. Plants then absorb the chlorine and sodium instead of needed plant nutrients such as potassium and phosphorus, leading to deficiencies. The chloride ions can be transported to the leaves where they interfere with photosynthesis and chlorophyll production. Chloride accumulation can reach toxic levels, causing leaf burn and die-back.

Rock salt also causes damage when salt laden snow is plowed or shoveled onto lawns and garden beds. Salts in the soil can absorb water. This results in less water being available for uptake by the plants, increasing water stress and root dehydration. This is referred to as physiological drought, which, if not corrected, can lead to reduced plant growth.

The displacement of other mineral nutrients by sodium ions can also affect soil quality. Compaction can increase while drainage and aeration decrease, generally resulting in reduced plant growth. Damage from salt in the soil can be delayed, with plant symptoms not appearing until summer or even years later. Symptoms may also become evident during periods of hot, dry weather.

The extent of damage can vary with plant type, type of salt, fresh water availability and volume, movement of runoff, and when salts are applied. De-icing salts without sodium are safer for plants than sodium chloride. Salts applied in late winter generally result in more damage than salts applied in early winter because there is a better chance the salt is leached away before active root growth in spring. The volume of fresh water applied to soils also impacts the amount of salts leached away, while rainfall can wash salt from leaves.

Common Symptoms of Salt Injury

  • Damage mostly on the side of the plant facing the road or sidewalk
  • Browning or discoloration of needles beginning at tips
  • Bud damage or death
  • Twig and stem dieback
  • Delayed bud break
  • Reduced or distorted leaf or stem growth
  • Witches’ broom development (tufted and stunted appearance)
  • Wilting during hot, dry conditions
  • Reduced plant vigor
  • Flower and fruit development delayed and/or smaller than normal
  • Fewer and/or smaller leaves than normal
  • Needle tip burn and marginal leaf burn
  • Discolored foliage
  • Nutrient deficiencies
  • Early leaf drop or premature fall color

Management Strategies for Mitigating Salt Injury

Reduce salt use. Combine salt with other materials such as sand, sawdust, or cinders that can provide grittiness for traction. De-icing materials that use salts other than sodium chloride, including calcium chloride, magnesium chloride, potassium chloride, or calcium magnesium acetate (CMA) are more expensive but can reduce injury to plants.

Make applications carefully. Applications should be targeted at walkways and roadways, not landscape beds or lawns. The flow of salt-laden runoff water should be considered for when snow melts. Avoid planting in areas where runoff naturally flows. Leaching soils by watering heavily can help remove salts from well-drained soils. This is not possible with poorly draining soils. Improve drainage of poorly drained soils by adding organic matter. To determine if you have high salt buildup in the soil, send a soil sample to the UMass Soil and Plant Nutrient Testing Laboratory.

Protect plants with physical barriers such as burlap, plastic, or wood. Use salt tolerant plants in areas near roads, driveways, and sidewalks. Remember that salt tolerant does not mean injury free.

The following is a table of the reported salt tolerance of selected trees and shrubs. It is important to keep in mind when choosing plants considered “salt tolerant” that the degree of tolerance and extent of damage are dependent on many factors, with tolerance varying in plants within the same species. Tolerance can also vary depending on method of salt exposure (spray vs. soil). There are conflicting reports for salt tolerance of many species. Soil type and climate variability can result in differences in plant response between areas.

Fertilizer vs. Plant Food: What’s the Difference?

The words fertilizer and plant food are often used interchangeably, but they are not technically the same thing. Gardeners use fertilizers to help enrich their soil, supplying it with the essential nutrients that plants need to grow and bloom correctly. Aside from hydrogen, oxygen, and carbon, plants require 13 other nutrients that they typically get from the soil. The most important of these nutrients, or the, “big three,” are nitrogen, phosphorous, and potassium, often referred to on fertilizer labels as N-P-K, for their periodic table abbreviations.

These three macronutrients are essential to the growth and health of all plants. Fertilizers namely contain these three nutrients, as well as other nutrients which help plants thrive, plus a few fillers. Gardeners add fertilizers to enrich the soil when it has become depleted. Fertilizers work to enrich the soil, while plants use the nutrients found in the soil, and in the environment, to create their own food.

To put it simply, fertilizers and products that are labeled, “plant food,” are really just soil additives that contain lots of nutrients. If the soil in your garden beds contain the proper nutrients needed for healthy plant growth, then your soil is providing your plants with everything they need to make their own food.

What is Fertilizer?

Plant fertilizers are a combination of macronutrients, micronutrients, and fillers, or ballast. Some types of fertilizers are comprised of equal amounts of the, “big three,” macronutrients nitrogen, phosphorous, and potassium. These are commonly labeled as N-P-K 10-10-10 or 20-20-20. The numbers represent the percentage of each nutrient in the fertilizer. The first number is for nitrogen, the second for phosphorous, and the third represents potassium.

Some fertilizers contain a larger amount of one of the nutrients than the other two. Nitrogen is used to promote foliage growth, so a fertilizer that is made specifically for foliage plants may be composed of 20-5-5, for example. Certain plants require more of one nutrient than the others, so there are fertilizers with all different ratios of N-P-K in order to meet specific needs.

Fertilizers are also made up of micronutrients like calcium and iron. Organic fertilizers often contain the micronutrients boron, copper, iron, chlorine, manganese, molybdenum, calcium, and zinc. A balanced fertilizer, for example, one that is labeled 10-10-10 is comprised of 10 percent of each macronutrient for a total of 30 percent macronutrient content. Another 10 to 20 percent of the fertilizer is made up of various micronutrients, while the remaining 50 percent is filler. The majority of all fertilizers are made up of micro and macro nutrients, but the bulk of the content within most fertilizers are fillers. Fillers are not just there to take up space, but are actually designed to help distribute the valuable nutrients and increase their absorption capability.

What is Plant Food?

Fertilizers are made for the sole purpose of revitalizing soil in order to provide plants with nutrients, but it is up to the plants themselves to concoct their own meals. Plants make their food with the nutrients that they absorb from the soil in combination with a special blend of air, water, and sunlight. The air provides the plant with carbon dioxide which enters through its leaves.

As the carbon dioxide comes in through the plant’s foliage, it meets chlorophyll, which absorbs and stores the sun’s energy, resulting in chloroplasts. The chloroplasts inside chlorophyll combine with the carbon dioxide to create a simple sugar. This sugar spreads out with the help of absorbed water traveling through the entire plant.

Water moves up through the roots and into the plant, taking the sugar with it, as well as minerals and nutrients taken from the soil that are vital for the process of photosynthesis to function as needed. The presence of water is also essential to maintaining the turgidity of the plant’s cells. If the plant is not getting sufficient water, the cells will not be as turgid, resulting in wilt.

Fertilizers are added to the soil in order to help provide the elements needed for plants to create their own food. Plant food is made from nutrients in the soil as well as other essential elements, like air, water, and sunlight. When fertilizers contain high levels of nitrogen, phosphorus, and potassium, but lack the other needed micronutrients, plants will receive inadequate nutrition. Plants need all 13 nutrients to grow well and provide balanced nutrition.

Synthetic Versus All-Natural Fertilizer

Different fertilizers get their nutrients from either organic or chemical forms. Organic fertilizers are made from manure, compost, or fish meal. Chemical nutrients are purer in form but can be rather costly. Chemical fertilizers are usually water-soluble and are often added to the plants directly during irrigation by diluting them into water and then using that water to irrigate your plants so that the nutrients can be absorbed by the plants immediately. Organic nutrients take a bit longer to break down into the soil, but if you are a home gardener with your own compost pile, using organic fertilizer can save you a lot of money.

Chemical fertilizer, or synthetic fertilizer is made from liquid ammonia. Liquid ammonia is quite cheap to produce, and its impact on American agriculture has been massive. Between the years 1950 and 1975, the output of production from American farms has increased by over 50 percent while farm labor hours decreased by an astounding 60 percent.

The increased use of chemical pesticides and fertilizers, as well as genetic improvement and mechanized labor, all combined to create this change which has revolutionized agriculture in America. Unfortunately, the boost in output from American farms comes at a steep cost. Atmospheric nitrogen overload from synthetic fertilizers has been credited by environmental scientists, as the primary cause of global pollution, according to a report by the World Resources Institute.

Natural fertilizer, or fertilizer made from all-natural sources, is a much more environmentally friendly way to provide our garden plants with the nutrients they need. Cottonseed meal, feather meal, seaweed, fish waste, bone and blood meal, and poultry manure are all common ingredients in organic fertilizer. All-natural fertilizers require the presence of soil microorganisms in order to be effective. According to the Colorado State University Extension website, natural fertilizers require soil microorganisms, which are dependent on sufficient moisture and temperatures above 50 degrees Fahrenheit.

Compost is an all-natural alternative to fertilizer that you can make at home in a compost bin or a simple pile. Compost contains all of the 13 needed nutrients that are vital to plant growth, as well as oxygen and water. Compost can be started in your own backyard by gathering yard trimmings, grass clippings, kitchen waste, shredded newspaper, and dried leaves. Layer these ingredients in a compost bin with layers of soil, water it regularly to keep the contents moist and leave it to decay over time, turning the pile over occasionally to help speed up the decomposition process. Compost will become mature and ready to use as plant food in 30 days to three months time.

Soil pH

Another important factor when it comes to the ability of plants to absorb fertilizers and create their own food is the pH level of the soil they are grown in. Soils with excessively high pH (7 or higher) or low pH (5.5 and below) are not welcoming to nutrients. In soils like these, the nutrients present in fertilizers are either too soluble or not soluble at all, and the plants can’t absorb them, or they become toxic to the plants. Soil with too high or low pH levels can be amended with lime or elemental sulfur to lower or raise the pH.

Testing and Dilution

Nutrient intake of garden plants is a finely-tuned system. Too much or too little of any one nutrient can upset the system. A soil test will help you to determine the content of your soil and the type and amount of fertilizer your soil needs. If either inorganic or organic fertilizers are applied too heavily to the soil, they can cause plant tissue to burn or become chlorotic, resulting in unhealthy or dead plants. Without a soil test, it can be very difficult to figure out what fertilizer is best and what amount of fertilizer is needed to balance out your garden soil. Once you have determined what your soil needs, read product labels carefully and follow directions to avoid toxicity problems. Many gardeners recommend diluting fertilizers to half strength before adding them to the soil to avoid overfertilization issues.

Common Questions and Answers About Fertilizer Versus Plant Food

Can fertilizer hurt plants?

Too much fertilizer can hurt plants as a result of them getting too much of the nutrients they need to survive. Over fertilization is harmful to plants because it causes them to grow faster than their roots can develop to support the new foliage. Too much fertilizer is also harmful to microorganisms in the soil and deposits excessive amounts of salt in the soil. Over fertilization also leads to illnesses such as iron chlorosis and root rot, as well as leaving plants more susceptible to illness and infestation in general. You can flush extra fertilizer out of your garden’s soil by giving your plants lots of fresh water to wash the fertilizer away.

Can fertilizer kill plants?

Fertilizers contain salts that, in excessive amounts, can be harmful to plants and even kill them. Plants that get too much fertilizer can also grow faster than their root systems can support their growth. Over fertilization also leaves plants susceptible to infestation by garden pests and infection by plant diseases, especially root rot and iron chlorosis. If your plants are experiencing harmful effects as a result of over fertilization, give them plenty of fresh clean water to flush out the buildup of salts and excess nutrients in the soil.

Can I make my own liquid fertilizer?

You can make your own liquid fertilizer out of seaweed, vegetable scraps, manure, or garden weeds by allowing materials that are high in nitrogen to soak in water. The amount of time your homemade liquid fertilizer will need to soak ranges from just one night to several weeks, depending on the material you’re using. Supplies you’ll need include a garden hose, bucket or other large container, and kitchen as well as a blender for some recipes. Your homemade liquid fertilizer should be prepared outdoors, as the mixtures can produce offensive smells.

  • Vegetable scrap fertilizer: Save the scraps and ends of vegetables you’d otherwise throw away in your freezer until you’ve collected a few quarts to use in homemade liquid fertilizer. Thaw the scraps and puree them in the blender with water until they’re a smooth liquid. Empty the blender into your bucket along with half a teaspoon Epsom salt and a capful of ammonia for each blender load you add. Continue until you’ve blended all of the vegetable scraps you saved. Stir the mixture in your bucket and allow it to soak overnight. This mixture is a liquid fertilizer concentrate. To make it ready to use, mix one quart of puree with a gallon of warm water in a spray bottle, and shake well. Apply this fertilizer to the base of plants.
  • Weed and grass clipping fertilizer: Save the weeds you pull from your garden or use clipped grass from mowing the lawn. In a five-gallon bucket, add a few handfuls of grass clippings or pulled weeds, then fill the bucket with water. Allow the mixture to steep outdoors for four weeks. When it’s ready, apply your homemade liquid fertilizer to the base of your plants.
  • Liquid manure fertilizer: Add a shovel full of the manure of your choice to a five-gallon bucket, and combine with water until the bucket is full. Allow this mixture to steep for four weeks, then apply to the soil at the base of your plants.
  • Compost tea: Mix a shovel full of finished compost with water in a five-gallon bucket. Let the mixture steep for four weeks, then it is ready to be applied to the base of plants.
  • Seaweed fertilizer: Add a few handfuls of seaweed to a five-gallon bucket filled with water. Let this combination steep for four weeks. When ready, apply to the base of your plants.

Do I need plant food?

If you are planting in a new garden bed in soil that has not been used before and is fertile and rich, you will not need to use plant food for the first season. You will also not need to use plant food at first when planting in commercial potting soil. However, after plants have been growing for a while in either new fertile soil or in commercial potting soil, they will take in the nutrients the soil contains, and plant food will become necessary to replace those nutrients.

How do I know if my plants need fertilizer?

Plants will show signs of malnutrition when fertilizer is needed. These signs include pale green or yellow foliage when nitrogen levels are low, chlorosis (dark green veins on pale green leaves) when potassium is low, and dull, dark green foliage with purple leaves at the base of the plant or reduced flowering when phosphorus is low. Blossom-end rot can indicate a deficiency of calcium. Ensure that foliage discoloration is not due to overwatering (for yellow leaves) or underwatering (if foliage looks dead or crisp) before applying fertilizer.

How do you fertilize a garden plant?

Fertilize garden soil in the spring before planting annual flowers and vegetables, while perennials are just beginning their growth for the season. Incorporate a general-purpose fertilizer into the soil at a depth of six inches where annuals and vegetables are growing. Where perennials are growing, work the fertilizer gently into the soil around the plants. Apply fertilizer again when plants are growing the quickest. This period is early in the spring for lettuce and other salad greens and the middle of summer for corn, tomatoes, potatoes, or squash. When growing long-season crops, use a small amount of fertilizer when you set seed, then apply more at the beginning of summer just before the plants are growing their quickest. When growing blueberries, apply fertilizer early in the season when buds are breaking. Fertilize strawberries after the first harvest. For ornamental trees, shrubs, or perennial plants, apply fertilizer when plants come out of dormancy at the beginning of their growing season.

Dry or granular fertilizers can be spread over a large area using a spreader or by hand, or they can be applied along the rows of your plants and seeds as a side dressing. Work dry fertilizer into the top four to six inches of soil using a hoe or spade, then water the fertilizer in to help it soak into the soil. Subsequent applications later in the season can be made just to the top inch of soil in garden beds or where plants grow in rows or at the drip line around trees and shrubs.

Liquid fertilizers are used by combining the fertilizer with the water you normally give your plants. Water-soluble fertilizers should be applied to the base of plants. Apply liquid fertilizer two to three weeks after planting. Before applying liquid fertilizer, water plants well with untreated water so that the roots will not be burned with fertilizer. Ensure that liquid fertilizers are diluted according to their package directions, as a too-strong mixture can also burn plants.

How long does fertilizer last in soil?

Different types of fertilizer take varying periods of time to break down in soil, making them appropriate for different uses. The nutrients in liquid fertilizers are available for plants to use immediately after application, and the fertilizer remains available in soil for only a short period of one or two weeks. Dry or granular fertilizer blends remain active in soil for six to eight weeks, after which period they should be reapplied.

How long does it take for granular fertilizer to work?

Quick-release fertilizers begin working within a few days, but their effects only last a short period of time before they must be reapplied. Plants begin taking in nutrients from quick-release fertilizer within 15 to 24 hours. With slow-release fertilizers, plants don’t begin to see effects for three to 10 weeks. However, the slower release time means these fertilizers are available for longer, and their effects continue much longer than quick-release fertilizers, meaning they don’t need to be reapplied as often. Consult the packaging of the particular fertilizer you’re using in your garden to find out how often your fertilizer should be reapplied.

How much liquid fertilizer does a plant need?

Liquid fertilizer should be diluted in water as directed on the packaging, and then that water should be given to plants as usual for their hydration. Once the liquid fertilizer is diluted, it should be distributed to plants at the same dosage as untreated water is normally given.

How often should I apply slow release fertilizer?

Slow-release fertilizers should be applied to the garden every six to eight weeks, unless the instructions given on their packaging indicate otherwise.

How often should I fertilize my tomato plants?

Fertilize tomato plants once just after planting them in the garden. Give tomatoes a second dose of fertilizer once they begin to set fruit. After tomato plants begin to develop fruit, nourish them with a light fertilizer every one or two weeks until the plant is killed by frost.

How often should you fertilize flowers?

Different types of fertilizer have different timelines for application, so always follow the guidelines provided by your fertilizer’s manufacturer as indicated on the packaging. Liquid or water-soluble fertilizers are normally applied every one or two weeks, and are always given mixed in with the water a plant normally receives. Slow-release fertilizers last several months once they’ve been applied. A slow-release fertilizer should be given at the beginning of the season just as plants start to grow. One dose is sufficient in northern areas, but in southern regions, a second dose may be needed when plants are growing at their fastest later in the season. Granular fertilizers should be used as a soil amendment mixed into the top four to six inches of soil just before planting.

Is granular fertilizer better than liquid?

Granular and liquid fertilizers have different benefits, so which is better will depend on what is important to each individual gardener and the specifics of their situation. Liquid fertilizers are better able to reach plants, as the nutrients in granular fertilizers stay located in the granule whereas liquid fertilizers deliver nutrients to plants through the movement of water underground. Granular fertilizers can contain more nutrients, so the danger of “burning” plants through over fertilization is more prevalent than with gentler liquid fertilizers. Liquid fertilizers have a uniform makeup that is the same throughout the mixture, while the nutritional makeup of granular fertilizers varies among granules. Liquid can be easier to apply than granular, though there may be some initial cost when transitioning to a liquid fertilizer if new equipment is needed. Granular fertilizer does not need to be applied as often as liquid and is cheaper when purchased in bulk.

Should I feed my plants every time I water?

Houseplants should be given water-soluble fertilizer once a week, while outdoor container plants should be fed with water-soluble fertilizer twice a week. Garden plants should get water-soluble fertilizer once every two or three weeks. Landscaping plants should receive water-soluble fertilizer once a month.

Should I water plants before fertilizing?

Before giving plants fertilizer, water them well so that the roots aren’t coming into contact with water containing the fertilizer when they’re dry. Applying fertilizer after watering your plants will help prevent damage from “burning” plants when they’re exposed to too much fertilizer.

What are some examples of natural fertilizers?

Natural fertilizers include manure, worm castings, peat, seaweed, and compost. These natural fertilizers can be used as a soil amendment, applied alone as a fertilizer, or can be included in homemade fertilizer mixtures.

What are the three fertilizer numbers?

The three numbers on fertilizer packages that are separated by hyphens provide the percentage of nitrogen, phosphorus, and potassium the fertilizer contains (in that order).

What fertilizer helps flowers bloom?

Fertilizers that are high in phosphorus aid in flower production. To increase blooming, look for fertilizers with a high second number, because the second number indicates the percentage of phosphorus the fertilizer contains.

What is a good fertilizer for orchids?

Gardeners should give orchids a balanced fertilizer such as a 20-20-20 blend that does not contain any urea weekly. Experts recommend giving a small amount of fertilizer at a time in an approach called fertilizing “weakly, weekly.” They suggest giving fertilizer at a quarter strength on a weekly basis.

What time of day should I fertilize my plants or flowers?

Plants should ideally be fertilized at the same time as you provide them with water, and when you water more than once per day, you should provide fertilizer in the morning. Plants are able to take in nutrients better before they’ve become stressed by the midday heat.

Which fertilizer makes plants grow faster?

To make plants grow faster, look for a high-nitrogen fertilizer. Fertilizers with a high first number will be high in nitrogen, because the first number indicates the percentage of nitrogen the fertilizer contains.

Want to learn about using fertilizer versus plant food?

UBC Botanical Garden covers Fertilizer Vs Plant Food

National Gardening Association covers Plant Food Vs Fertilizer

UCCE El Dorado County Master Gardener covers Perils of Over-Fertilizing Plants and Trees



Post this on your Pinterest board! I couldn’t find it to pin it!

Yes please! I second that motion.

Hi I am starting to grow roses. I only have a 2, 3 months old and 6 months rose plant. They were bare root roses when planted. I fertilized two of the older ones with granular 2 in one Advance Fertilizer, I want to switch to liquid fertilizer after two weeks is over. Will it harm the plants.
Thank you.


Anthropologic activities have transformed global biogeochemical cycling of heavy metals by emitting considerable quantities of these metals into the atmosphere from diverse sources. In spite of substantial and progressive developments in industrial processes and techniques to reduce environmental emissions, atmospheric contamination by toxic heavy metals and associated ecological and health risks are still newsworthy. Atmospheric heavy metals may be absorbed via foliar organs of plants after wet or dry deposition of atmospheric fallouts on plant canopy. Unlike root metal transfer, which has been largely studied, little is known about heavy metal uptake by plant leaves from the atmosphere. To the best of our understanding, significant research gaps exist regarding foliar heavy metal uptake. This is the first review regarding biogeochemical behaviour of heavy metals in atmosphere-plant system. The review summarizes the mechanisms involved in foliar heavy metal uptake, transfer, compartmentation, toxicity and in plant detoxification. We have described the biological and environmental factors that affect foliar uptake of heavy metals and compared the biogeochemical behaviour (uptake, translocation, compartmentation, toxicity and detoxification) of heavy metals for root and foliar uptake. The possible health risks associated with the consumption of heavy metal-laced food are also discussed.

Would a plant need light if the chemicals gained by photosynthesis were given through the roots or as a foliar spray? - Biology

Substrates that contain a high level of microbial activity and abundant organic matter such as coir and peat attract fungus gnats. For this reason, fungus gnats are a common problem when growing in coir.

Adult Fungus Gnats are small, delicate bodied, long legged mosquito like insects that commonly develop in organic growing mediums. The adults don’t damage plants per se. Their larvae, however, while feeding mainly on decaying plant material and fungi also feed on healthy plant roots and tunnel into stems of young cuttings and seedlings. Therefore, the larvae cause plant damage by feeding on the roots, thus interfering with the ability of plants to uptake water and nutrients, which results in wilting and stunted growth. Significant root damage and even plant death has been observed where high populations of Fungus Gnat larvae are present.

Additionally, larvae feed on fungal root zone pathogens and are capable of directly transmitting these pathogens, including Pythium spp., Fusarium spp., and Verticillium spp., from diseased to non-infected plant’s.

Fungus Gnat adults selectively deposit their eggs on the fungal mycelium. Phytopathogenic fungi such as Botrytis cinerea, Fusarium species and Phoma betae are preferably used as egg laying sources. Conversely, beneficial fungi such as Trichoderma are non-preferred nutrient sources, albeit fungus gnat larvae will also feed on Trichoderma and other beneficial fungi species to some extent.[1] Fungus Gnat adults are capable of carrying the aerial conidia of certain foliar and soil-borne plant pathogenic fungi such as Botrytis cinerea Pers.:Fr., F. avenaceum, F. acuminatum, T. basicola, V. dahliae Kleb., and V. albo-atrum, which can then be transmitted to healthy plants. The potential for both adult and larvae of Fungus Gnats to transmit disease means that the tolerance level for the presence of this pest may be very low, which is similar to other pests that vector diseases.[2]

The Fungus Gnat life cycle consists of eggs, four larval (instar) stages, pupa, and adult. In total, 21- 40 (typically 21-27) days, dependent on substrate and air temperature, are necessary to complete the entire life cycle. The adult lays its eggs in the substrate and the larvae inhabit the upper 3cm of the substrate before pupating and emerging from the substrate as adults.[3] The egg laying Fungus Gnat adults have a very short life cycle (7-10 days) however, in this time they can lay hundreds of eggs which hatch as larvae in five to six days. The larvae will feed on any organic matter present, including roots, for 10 to 14 days. See following image that shows the lifecycle of the Fungus Gnat.

Because the Fungus Gnat life cycle is very short and because female adults can lay so many eggs over a short space of time a Fungus Gnat population can quickly explode under the right conditions.

Fungus Gnats thrive in warm, wet, nutrient rich, organic environments. This environment is readily supplied in indoor hydroponic grow rooms where organic media is used. Because Fungus Gnats are attracted to organic media, infestations are a common problem for coir growers. For this reason, it is imperative that coir growers understand how to identify and combat this all too common coir loving pest.

Fungus Gnat Identification

Adult Fungus Gnats are about 2–5 millimeters long, gray to black, slender, small mosquito like flies with long legs and antennae, and one pair of wings. The adults are considered to be weak fliers and they often appear to dance about – flying in an irregular pattern – while taking short flights. Because adult Fungus Gnats do not fly well they tend to reside near the surface of the growing media.

Larvae are tiny (hardly visible to the naked eye) and have a shiny black head and an elongated, whitish-to-clear, legless body.

Yellow Sticky Traps are Imperative in ANY Grow Room

Yellow sticky traps act as the best early warning system for trapping and identifying adult Fungus Gnats. These traps are supplied through hydroponic stores and are cheap to purchase. Fungus Gnat adults are attracted to the colour yellow and when they land on the traps – which are covered in a thick glue like substance – the gnats become stuck. When large amounts of Fungus Gnat adults are present in the grow room the traps will literally be speckled with hundreds of gnats that have become stuck to the surfaces of the traps.

Studies have shown that sticky traps laid flat on the media surface capture about 50–60% more adult Fungus Gnats than cards placed vertically. Because sticky traps act both as an early warning system and as an efficient means of mass-trapping adult females, thus reducing the number of larvae in the next generation, I tend to place the traps both vertically and horizontally, at media level (horizontal on top of the substrate and vertically at the top of pots, underneath the plant canopy) in my grow room. Traps should be monitored daily to ensure the presence of Fungus Gnats in the grow room is identified early.

As a rule, the more adults that are trapped daily the higher the population of Fungus Gnat larvae in the substrate. Therefore, if the numbers of adults trapped daily increases on a daily basis (e.g. 5 one day and 10 the next day) this probably indicates the population is increasing quickly and measures should be taken to control the population.

An effective way to detect the presence of Fungus Gnat larvae is to insert slices or wedges of potato onto the surface of the coir. Slice raw potatoes into about approximately 1-inch by 1-inch by 1/4-inch pieces. Place the slices next to each other on the surface of your potting media to attract Fungus Gnat larvae. Larvae will migrate to the potato and start feeding within a few days. The potato slices should be turned over to look for larvae present on the underside.

Prevention and Control

A point I stress again and again in IH is that prevention is a far better practice than cure. That is, by the time you identify a problem, plant health and growth may already have been impacted. This, among other things, applies to pest control. Therefore, practices that prevent Fungus Gnats from taking hold in a crop should take priority over eliminating them once high numbers are present.

The first line of defense against Fungus Gnats comes down to screening inlet air (to keep Fungus Gnats found outdoors out of the grow room environment), grow room moisture management and sanitation practices. Where clones or seedlings are obtained from outside sources these should be quarantined from the grow environment and treated with an insecticidal drench two or so days before being introduced into the grow room.

Fungus Gnats are primarily a problem under conditions of excessive moisture. Maintaining nutrient temperatures at ideal levels, the use of well-drained growing media and not over-watering plants may help avoid issues with water-borne plant pathogenic fungi which act as the food source for Fungus Gnats, reducing the possibility of disease transmission by the larvae and adult. Additionally, the accumulation of water and presence of algae may lead to abundant populations of Fungus Gnats. This means keeping the nutrient run off tank/reservoir tightly sealed, cleaning up any spills, and keeping surfaces dry at all times.

It is also important to remove plant material and growing medium debris immediately from the grow room as Fungus Gnat adults may emerge from disposed growing medium or plant debris and migrate onto the crop.

Keep Insects Outdoors by Filtering the Air that is drawn into the Grow Room

Screening inlet air with HEPA filters is an ideal means of filtering out all insects and high degrees of airborne microbial contaminants (bacteria, fungi, viruses). This said, placing any filter over an intake port or inlet fan works well as long as the filter is fine enough to act as a barrier against pests.

Contaminated Substrates

It is important to note that one potential (and not necessarily rare) source of Fungus Gnat infestation is contaminated substrates that are purchased through garden supplies or hydroponic stores. This is important to understand because even where best practice (such as screening and sanitation) is employed, Fungus Gnats may find their way into the grow room through contaminated bagged products of coir. For this reason, always purchase a reputable brand of coir which is produced to quality assurance standards (e.g. RHP standard). These products in some cases undergo sterilization/pasteurization during manufacture which kills any living biological matter (e.g. insects, larvae, bacteria and fungi) in the substrate prior to bagging. In other cases high quality production standards are applied to ensure a quality, albeit biologically active, non-sterilized product. For example, Canna claims to have taken the latter non-sterile route so as their product can, among other things, maintain viable Trichoderma which is naturally occurring in coir.

However, there is the potential, no matter what the treatment or quality assurance standard that Fungus Gnats could have laid eggs in a bagged coir substrate during shipping or storage where entry, through even the smallest holes in a bag, can be gained by adult Fungus Gnats. Thus, contamination can potentially occur along the supply chain (i.e. while the product is stored with a producer/supplier, wholesaler or retailer). Not to be alarmist but it is something coir growers need to be aware of.

If you are concerned about the possibility of a bagged coir substrate product being a potential source for a Fungus Gnat infestation, one option is to treat the coir before it enters the grow room. This really comes down to drenching the coir with the pesticide/insecticide spinosad prior to taking it into the grow room. I cover how to do this on page…..

Control – Dealing with a Fungus Gnat Infestation

Okay, so you have filtered inlet air and been fastidious about grow room sanitation and you still have a Fungus Gnat infestation. Don’t panic… dealing with them is relatively easy!

Because Fungus Gnat larvae are of the greatest concern, due to causing direct root damage, and because most of a Fungus Gnat’s life cycle is spent as a larva, the most effective control method targets larvae rather than attempting to directly control the mobile, short-lived adults. Therefore, substrate drenches that target the larvae prove to be the most effective means of controlling a Fungus Gnat infestation.

Time of Application Considerations when Choosing a Control Option/Product/Approach

If you identify the presence of Fungus Gnats, how you combat them (i.e. insecticide choice etc) should be done with careful consideration. This applies to which point of the crop cycle you are at (i.e. time before harvest), and how severe the infestation is. Key factors that need to be considered are the withholding periods of the drench/insecticide that you use and its toxicity potential to the end consumer if trace amounts remain residual in the harvested product.

What I will do now is outline two different approaches I take – one using spinosad, an OMRI listed (organically certified) agrochemical product, and a second option using a combination of predatory nematodes (Steinernema feltiae) and neem oil – the latter being for the die hard “I would never use an agrochemical insecticide no matter how safe they claimed it was” ‘hydro’ growing crew.

Further to this, it is important to note that regardless of its OMRI organic listing, Spinosad (option #1 for controlling Fungus Gnats) is not permitted for use on medical marijuana products as outlined by Washington State regulators (here and here)

This, I have been informed, really comes down to labeling compliance regulations. Basically anything not FIFRA (The Federal Insecticide, Fungicide, and Rodenticide Act) exempt, or that does not contain language on the label that allows for use on “other, not listed” crops, is not permitted. In other words the labels currently used on Spinosad products are too specific regarding what crops it is labeled for use on, without actually stating cannabis. I expect at some point, Spinosad may be labeled according to meet codes that will allow for its use with medical marijuana. However, until then be aware that if Spinosad residues are found in lab ‘Medicinal’ cannabis tests this will result in a fail re pesticide compliance.

For this reason, Spinosad should not technically be used in the production of “medical” marijuana and option #2 should be used by “Med” growers.

Spinosad Drench

Spinosad, produced by Dow AgroSciences, is technically an organic (considered nonsynthetic) product and certain formulations are listed for use by the Organic Materials Research Institute (OMRI) for organic use in the US and various other countries. Due to its low effective use rate, safety to the environment, safety to mammals, and safety to beneficial insects, spinosad was registered under the US EPA’s reduced risk program. Spinosad was also awarded the Presidential Green Chemistry Challenge Award in 1999.

Spinosad is produced by aerobic fermentation of the actinomycete (bacteria) species Saccharopolysora spinosa. Spinosad contains two chemicals, spinosyn A and spinosyn D. These are crystalline solids with low odor, no volatility, and with low water solubility. The half-life of these compounds on a plant leaf is about 2-16 days. Spinosad is slowly and poorly absorbed through the skin. Dermal exposures in the rat for 24 and 120 hours resulted in only 1 and 2% absorption, respectively. Spinosad, which is absorbed via the oral or dermal routes of exposure, has been found to be rapidly metabolized and eliminated from the body. For example, 95% of the spinosad residues in rats are eliminated within 24 hours (U.S. EPA). Trace residues of spinosad that may be absorbed from food or water by terrestrial and aquatic organisms have been found to be readily metabolized and excreted and, as a result, spinosad and its metabolites do not accumulate in living tissues. Spinosad elimination half-lives of around 4 days are observed in fish. Basically, spinosad has very low toxicity to non-target organisms (e.g. humans) and by agrochemical standards is the safest choice of insecticide that, arguably, can be used.

Spinosad is shown to have high efficiency when dealing with Fungus Gnat larvae. For example, one study in an insecticide non-resistant cohort showed spinosad, trichlorphon, deltamethrin, spintoram, permethrin, and malathion had the greatest effect on Fungus Gnat larvae populations respectively (i.e. spinosad provided the most effective control) . [4] Spinosad is a fast-acting material that acts on the insect primarily through ingestion, but also by direct contact. It activates the nervous system of the insect, causing loss of muscle control. Continuous activation of motor neurons causes insects to die of exhaustion within 1-2 days.

When used as a drench in low CEC substrates’ such as rockwool or expanded clay, spinosad has systemic properties and is uptaken and distributed throughout the plant, offering protection against pests such as whitefly[5] and spider mite[6] for up to 30 days after treatment. One author concluding that apparently, spinosad has systemic properties and quantities as low as 1 mg/plant could protect tomato plants from mite infestation.” This author also concluding that the persistence (withholding period) of systemically applied spinosad to tomato was up to 45 days.[7] However, what’s interesting about this is that when spinosad is applied to substrates with varying percentage of clay and organic matter these systemic properties aren’t apparent, or are greatly reduced. An immediate explanation for this is that organic matter, due to its CEC properties, binds spinosad making it unavailable for plant uptake. While more research is needed, given coir is an organic substrate and has moderately high CEC this possibly means that very little spinosad is uptaken by coir grown plants and this reduces the possibility of spinosad residues being present in the harvested product. Further, given the low levels used, low absorption rate, low toxicity and rapid metabolization by mammalian species this makes it a very efficient and safe option for killing Fungus Gnat larvae in organic substrates.

There are several spinosad products/brands on the market (e.g. Conserve, Entrust, Monterey, Greenlight) with varying percentages of spinosad as the active ingredient.

For hobby growers who are producing on a small scale, the easiest way to go about things is to purchase small volumes, rather than having to store large amounts. For this reason, I typically purchase Monterey Garden Insect Spray which contains 0.5% spinosad as the active ingredient. This is used at 4 tablespoons per US gallon when applied as a media drench. This converts in metric to 15ml/L or 75ppm of spinosad in the diluted drench solution.

Depending on your locale spinosad products are available under different brand names. For example, in Australia, Yates sells Nature’s Way Fruit Fly Control, Active: 0.24g/L spinosad (200ml) or Yates Success Natralyte Insect Control, Active: 1.0% spinosad (200ml). These are easily accessible options for Australian growers and would be used at 8 tablespoons per US gallon or 30ml/L (Nature’s Way Fruit Fly Control) or 2 tablespoons per US gallon (7.5ml/L) with Success Natralyte Insect Control.

When mixing and applying the drench be sure to adhere to any safety warnings on the product label and wear gloves and eyewear. Mix with mains water and pH adjust to 5.8 before applying the drench to the substrate. It is important that you thoroughly drench the entire surface area of the substrate evenly to ensure all larvae come in contact with the spinosad (spinosad is most effective as a contact spray/drench). Drench the media evenly and well. Apply when the lights first turn off and leave in substrate overnight before flushing with a 1/2 strength pH adjusted nutrient solution an hour before the lights come on. Go back to your normal nutrient irrigation regime thereafter. What I also do is spray around the tops of the pots with a permethrin or deltamethrin based fly spray to kill adult Fungus Gnats that reside on the substrate surface.

Pest Resistance to Insecticides

It is important to note that because of the rapid reproductive rate of many pests a generation of many insects can take place in a few weeks and many generations can be produced in a single season or year. Repeated use of the same class of pesticide to control a pest can cause undesirable changes in the gene pool of a pest leading to another form of artificial selection, pesticide resistance. When a pesticide is first used, a small proportion of the pest population may survive exposure to the material due to their distinct genetic makeup. These individuals pass along the genes for resistance to the next generation. Subsequent uses of the pesticide increase the proportion of less-susceptible individuals in the population. Through this process of selection, the population gradually develops resistance to the pesticide. The faster the development rate of the pest species, the faster the pesticide resistance occurs.

For example, resistance to two organophosphorus insecticides chlorfenvinphos and primiphos-ethyl among Fungus Gnat populations has been reported in the UK where these chemicals were commonly used.[8] Similarly, studies have shown that some populations have become resistant to malathion and permethrin treatments due to the heavy use of malathion and permethrin which created resistance problems. Therefore, chemical drenches that are effective in one location (e.g. Australia) may not be as effective in another location (e.g. the U.S.). For this reason, three days after drenching I replace all the yellow sticky traps in the grow room with new ones and monitor these closely for the next few days to see if the treatment has been effective i.e. spinosad will kill the larvae very quickly and adults will stop emerging from the substrate almost immediately. As a result, the number of adult flies caught on the traps should be absolutely minimal to nil several days after drenching. If reasonably high numbers, 4-5 days after treatment, are still being trapped this indicates the drench has been less effective than desirable and another type of drench should be employed. To date, I haven’t found any resistance problems regarding spinosad use however, it is something that you need to be aware of. For example, some years ago I used permethrin as a drench and found over time that the Fungus Gnat population was becoming resistant. The permethrin still worked reasonably well however, more and more Fungus Gnats were surviving treatment. At that point I switched to another drench (spinosad) and this worked extremely well (100% control).

That’s pretty much it. You’re now up to speed on controlling a Fungus Gnat population with spinosad. Job done… let’s move on to option two.

Option #2 – Neem Drench and Foliar Spray + Predatory Nematodes

Okay so you’re a diehard anti-agrochemical pesticide proponent and you don’t like the idea of using spinosad no matter how safe it appears on paper. It is an agrochemical after all… What to do?

Well you have a couple of good botanical and biological pest control options. Firstly, you can reduce and control the population by applying a neem drench and foliar spraying with neem every three days, or you can combine this very safe organic treatment (neem) with predatory nematodes.

The chemicals isolated from neem can be categorized into two groups: isoprenoids and non-isoprenoids . Non-isoprenoids are amino acids, carbohydrates, flavonoids and others, while isoprenoids contain compounds such as azadirachtin. The most important compound in neem for pest control is azadirachtin, which approximates the shape and structure of hormones vital to the lives of insects. The bodies of insects absorb the neem compounds as if they were their real hormones, and this blocks their endocrine systems. The resulting deep-seated behavioral and physiological aberrations leave the insects so confused in brain and body that they cannot reproduce and their populations plummet. Additionally, their feeding cycle is interrupted. Therefore, azadirachtin acts to break the feeding and breeding cycle in many species of insects, including fungus gnats.

One quite amazing feature of neem is that it presents low toxicity to many beneficial insects which prey on plant pests. What this means is that neem can be used in conjunction with fungus gnat predators such as Steinernema feltiae[9]. In fact, studies have shown that a higher degree of control is exhibited when neem and predatory insects are applied together.

It is important to understand that neem doesn’t provide the same level of control that spinosad does when used as a substrate drench for control of larvae.[10] However, when used correctly it will offer good control and reduce the Fungus Gnat population. Neem needs to be applied every 3 days as a drench. Additionally, spray the plants at the same time to target the adults, ensuring good coverage until run off. Pay particular attention to spraying the underside of leaves and spray thoroughly around the surface of the growing media where adult Fungus Gnats reside in large numbers. Always spray plants when the lights are off to avoid plant burning.

Most hydroponic stores stock neem oil under various brand names. Neem products can vary significantly in quality and purity. Speak to your hydroponic supplier and ask him/her about product options and recommended usage rates etc.

As a tip, neem can leave the final produce with a bitter taste if applied too close to harvest. For this reason, cease drenching and foliar feeding neem at least a week before harvest.

Predatory Insects

Predatory controls, such as soil-dwelling predatory mite, Stratiolaelaps scimitus, a rove beetle, Dalotiacoriaria Kraatz, and the entomopathogenic nematode, Steinernema feltiae, are shown to provide a high degree of control in suppressing or regulating Fungus Gnat populations. For example, one study (2008) found that Steinernema feltiae (S. feltiae) gave 90% control of the third instar L. ingenua larvae when S. feltiae larvae were incorporated in the growing medium at the rate of 74 nematodes/cm2.[11] An earlier study by Nickle and Cantelo (1991) reported 72–81% mortality to the second instar to fourth instar L. ingenua larvae where S. feltiae at the rate of 620 nematodes/cm2 was applied as a drench treatment.

It is important to note that the use of predatory insects is most successful where alternative plant protection strategies (moisture management, sanitation, repellent materials), and/or where compatible insecticides are implemented simultaneously in the case of an infestation.[12]

One highly successful approach here is to use neem as a media drench in conjunction with S. feltiae. One study by Krishnayyaand et al (2002), showed neem at 5- 10 mL L -1 is compatible with the use of S. feltiae. The authors concluded that neem can be safely mixed at the field recommended concentrations with juveniles of S. feltiae for application. [13]

On this note, a Fungus Gnat predator I have found very effective is Steinernema feltiae however, there are a few things growers need to be aware of when using this predatory nematode.

Steinernema feltiae(S. feltiae)

Predatory nematodes such as S. feltiae can be used to effectively control Fungus Gnats. However, there is a caution here re hobbyist/novice indoor growers. That is, often fungus gnat populations aren’t discovered by many growers until the population/infestation is very high and ordering biological controls can mean waiting several days for them to arrive, allowing the Fungus Gnat infestation to explode in the interim. This presents as a problem because the application of Steinernema feltiae soon after Fungus Gnats are first detected, while the population is relatively low, provides the best control. However, with the application of a neem drench and foliar spray to begin attacking the Fungus Gnat population, while you wait for your Steinernema feltiae to arrive, this presents as less of a problem. I.e. a neem drench and foliar spray will begin controlling the Fungus Gnat population and when you receive the Steinernema feltiae the population of Fungus Gnats is already under attack by neem. Because the use of neem and Steinernema feltiae are compatible you simply add the Steinernema feltiae to the substrate when you receive them.

Steinernema feltiae control the Fungus Gnat larvae by infecting, feeding, reproducing inside the fly larva and ultimately killing the larva. Nematodes such as Steinernema felitae that infect Fungus Gnats can be ordered by telephone or ordered online. Additionally, some hydroponic stores will order them for you. They arrive in a plastic container, cooled by an ice brick during transport and should be kept in the fridge (not the freezer) until use (if ordering through a hydroponic store be sure to tell the supplier to store the nematodes in a fridge until collection). Nematodes must be used within two weeks of receiving them.

It is important to note that Steinernema feltiae are most active/effective when used in air temperatures of below 28°C. For example, Koller (2011) found that control of Fungus Gnats with Steinernema feltiae was most successful, with an efficacy of 69–90% at 24°C.[14] For this reason, ensure that your grow room environment is not overheated and that ambient air temperatures are conducive for Steinernema feltiae (<28°C). Additionally, what I would advise if dealing with a high population of Fungus Gnats is to apply the Steinernema felitae at 2-3 times the supplier recommended rate to achieve a large and stable population quickly.

A word of caution about a few commonly recommended Fungus Gnat control options

Various Fungus Gnat control methods are recommended by growers on forums. However, some of these methods are shown to be largely ineffective in studies. For example, some recommend mixing diatomaceous earth (DE) into the substrate to control Fungus Gnat larvae.

DE is composed of ancient siliceous skeletonized diatoms, which remove the insect cuticle waxes, absorb oils and waxes on the outer cuticle, or disrupt the integrity of the insect cuticle resulting in extensive loss of water from the insect body. However, the use of DE relies on the insect to make direct contact with it, and while some larvae may come into contact with DE others may not. Further, when diatomaceous earth becomes moist, it loses any abrasive properties.[15] Thus, using diatomaceous earth in a moist substrate is an ineffective means to combat Fungus Gnats.

Others recommend the use of neem cake amended coir substrates. However, while this can prove to be an effective method for controlling Fungus Gnats, while the research is somewhat variable, several studies show that neem cake’s active constituent azadirachtin potentially disrupts beneficial microflora (bennies) and enzyme activity in soils and substrates.[16] , [17], [18], [19] Therefore, while offering effective control over Fungus Gnats, neem cake amended coir may not provide a conducive environment for bennies such as Trichoderma spp. Other than this, the potential for azadirachtin to interrupt enzyme activity is not a good thing.

Another issue with neem cake is that it provides relatively high amounts of nutrients i.e. neem cake contains more nitrogen (2-5%), phosphorus (0.5-1.0%), calcium (0.5 -3%), magnesium (0.3 – 1 %) and potassium (1 – 2 %) than farm yard manure or sewage sludge.[20] Neem cake also provides varying levels of micronutrients. What this means is that while neem cake is a good source of fertilizer for organic growing, its use in hydroponics, where the nutrients supplied to the plants can be highly controlled through ppm of each nutrient species in solution, is less than ideal where hydroponic nutrients are used.

Another method that is commonly recommended is to place sand or diatomaceous earth on top of the media to create a barrier, which is thought to interfere with the ability of adults to lay eggs and to stop adults from emerging from the substrate. However, studies have shown that placing diatomaceous earth or sand on the substrate surface has little effect on fungus gnat adult emergence or inhibiting females from laying eggs because these physical barriers contain small openings that allow larvae to pupate, and adult females to lay eggs.[21]

Yet others recommend the use of the bacterium Bacillus thuringiensis (BT). However, my own experiences with using BT and that of several studies are that, at best, BT offer only limited control and, at worst, are largely ineffective. One study that compared BT and predatory nematodes against the efficiency of pesticides concluded BT effectiveness would be reliant on the BT being applied before the Fungus Gnat populations build up and before overlapping generations develop.[22] In another study (2011) that compared the efficiency of Steinernema feltiae, neem oil and BT to control fungus gnats the author concluded that control with the nematode Steinernema feltiae was most successful, with an efficacy of 69–90% at 24°C air temperature. Azadirachtin (Neem-seed oil) could be an alternative under hot conditions (>28°C). Bacillus thuringiensis israelensis (BT), however, showed only a minor effect (1-51% efficacy).” [23]

Yet others state that hydrogen peroxide (H2O2) can be used for Fungus Gnat control. However, some issues present. These being 1) H2O2 is a potent oxidising agent that attacks and breaks down all organic matter (e.g. Fungus Gnat eggs and larvae) including the roots of plants. This means that when used at too high levels it can lead to root damage/burning 2) H2O2 is also uptaken by plants. Studies show that when H2O2 is applied to soils endogenous levels of H2O2 increase in the plant tissue. This can lead to phytotoxicity when application rates are excessive[24] 3) H2O2 products can vary widely in composition, which effects the required dilution rates 4) H2O2 reacts strongly with organic molecules rendering its oxidising potential ineffective in a short space of the time. For example, one study showed that 10 g·L-1 of peat reduced the amount of H2O2 and peroxyacetic acid from activated peroxygens by 33% and 50% respectively after 4 hours contact time.[25] There would therefore be some concerns about whether, 1) Fungus Gnat larvae would be exposed to enough oxidising agent (ppm in solution/substrate) for enough time to ensure high mortality rates (i.e. effectiveness is reliant on time of exposure and the levels of hydrogen peroxide the Fungus Gnat larvae are exposed to) and 2) whether the exposure time and the levels of H2O2 required to achieve a high mortality rate would not also prove damaging to the crop through root burning and/or phytotoxicity.

Bottom line on H2O2 … my advice is that more reliable Fungus Gnat control options exist.

[1] Kühne, F. and Heller, K (2010) Sciarid fly larvae in growing media – biology, occurrence, substrate and environmental effects and biological control measures

[2] Cloyd, R.A. (2015) Ecology of Fungus Gnats (Bradysia spp.) in Greenhouse Production Systems Associated with Disease-Interactions and Alternative Management Strategies, Insects 2015, 6, 325-332 doi:10.3390/insects6020325

[3] Evans, M.R. et al (1998) Fungus Gnat Population Development in Coconut Coir and Sphagnum Peat – based substrates

[4] Muhammad Hussnain, B. et al (2014) Efficacy of Different Insecticides Against Mushroom Sciarid Fly (Lycoriella auripila) in Punjab, Pakistan

[5] Van Leeuwen, T. Van de Veire, M, Dermauw, W. Tirry, L. (2006) Systemic toxicity of spinosad to the greenhouse whiteflyTrialeurodes vaporariorum and to the cotton leaf worm Spodoptera littoralis

[6] Van Leeuwen T Dermauw W, van de Veire M, Tirry L (2005) Systemic use of spinosad to control the two-spotted spider mite (Acari: Tetranychidae) on tomatoes grown in rockwool.

[7] Van Leeuwen, T. Van de Veire, M, Dermauw, W. Tirry, L. (2006) Systemic toxicity of spinosad to the greenhouse whiteflyTrialeurodes vaporariorum and to the cotton leaf worm Spodoptera littoralis

[8] Shamshad, A. Clift, A and Mansfield, S. (2008) Toxicity of six commercially formulated insecticides and biopesticides to third instar larvae of mushroom sciarid, Lycoriella ingenua Dufour (Diptera: Sciaridae), in New South Wales, Australia

[9] Krishnayyaand, P.V. Grewal, P.S (2002) Effect of Neem and Selected Fungicides on Viability and Virulence of the Entomopathogenic Nematode Steinernema feltiae. Biocontrol Science and Technology, Volume 12, Number 2, 1 March 2002, pp. 259-266(8)

[10] Premachandra, D. W.T.S. Borgemeister, C Poehling, H-M (2006) Effects of Neem and Spinosad on Ceratothripoides claratris (Thysanoptera: Thripidae), an Important Vegetable Pest in Thailand, Under Laboratory and Greenhouse Conditions

[11] Shamshad, A. Clift, A and Mansfield, S. (2008) Toxicity of six commercially formulated insecticides and biopesticides to third instar larvae of mushroom sciarid, Lycoriella ingenua Dufour (Diptera: Sciaridae), in New South Wales, Australia

[12] Cloyd, R. A. (2015) Ecology of Fungus Gnats (Bradysia spp.) in Greenhouse Production Systems Associated with Disease-Interactions and Alternative Management Strategies

[13] Krishnayyaand, P.V. Grewal, P.S (2002) Effect of Neem and Selected Fungicides on Viability and Virulence of the Entomopathogenic Nematode Steinernema feltiae. Biocontrol Science and Technology, Volume 12, Number 2, 1 March 2002, pp.259-266(8)

[14] Koller, M. (2011) Comparison of Steinernema Feltiae, Bacillus thuringiensis israelensis and Azadirachtin to Control Sciaridae in Organic Potted Herbs

[15] Korunic, Z. 1998. Diatomaceous earths, a group of natural insecticides. J. Stored Prod. Res. 34:87–97.

[16] Kizilkaya, R. Samofalova, I. Mudrykh, N. Mikailsoy, F. Akca, I. Sushkova, S. and Minkina, T. (2015) Assessing the impact of azadirachtin application to soil on urease activity and its kinetic parameters.Turk J Agric For(2015) 39:c TUBİTAK doi:10.3906/tar-1406-85

[17] Gopal, M. Gupta, A. Arunachalam, V. Magu, S.P. (2007) Impact of azadirachtin, an insecticidal allelochemical from neem on soil microflora, enzyme and respiratory activities

[18] Elnasikh M. H., Osman A. G. and Sherif A. M. (2011) Impact of Neem Seed Cake on Soil Microflora and Some Soil Properties

[19] Wan, M.T., Rahe, J.E., 1998. Impact of azadirachtin on Glomus intraradices and vesicular-arbuscular mycorrhiza in root inducing

transferred DNA transformed roots of Daucus carota. Environ. Toxic. Chemistry 17, 2041–2050.

[20] Radwanksi, S. A. and Wickens, G. E. (1981). Vegetative fallows and potential value of the neem tree in the tropics. Econ. Botany. 35:398-414.

[21] Cloyd, R.A. Dickinson, A. Kemp, K.E. Effect of diatomaceous earth and Trichoderma harzianum T-22 (Rifai Strain KRL-AG2) on the fungus gnat Bradysia sp. nr. coprophila (Diptera: Sciaridae).J. Econ. Entomol. 2007, 100, 1353–1359. – see also Cloyd, R.A. Dickinson, A. Effects of growing media containing diatomaceous earth on the fungus gnat Bradysia sp. nr. coprophila (Lintner) (Diptera: Sciaridae). HortScience 2005, 40, 1806–1809.

[22] Shamshad, A. Clift, A and Mansfield, S. (2008) Toxicity of six commercially formulated insecticides and biopesticides to third instar larvae of mushroom sciarid, Lycoriella ingenua Dufour (Diptera: Sciaridae), in New South Wales, Australia

[23] Koller, M. (2011) Comparison of Steinernema Feltiae, Bacillus thuringiensis israelensis and Azadirachtin to Control Sciaridae in Organic Potted Herbs

[24] Karajeh, M. R. (2008) Interaction of Root-Knot Nematode (Meloidogyn Javanica) and Tomato as Affected by Hydrogen Peroxide


The plant's common name refers to Venus, the Roman goddess of love. The genus name, Dionaea ("daughter of Dione"), refers to the Greek goddess Aphrodite, while the species name, muscipula, is Latin for both "mousetrap" and "flytrap". [7] [8] The Latin word muscipula ("mousetrap") is derived from mus ("mouse") and decipula ("trap"), while the homonym word muscipula ("flytrap") is derived from musca ("fly") and decipula ("trap"). [9] [10] [8]

Historically, the plant was also known by the slang term "tipitiwitchet" or "tippity twitchet", possibly an oblique reference to the plant's resemblance to human female genitalia. [7] [11] The term is similar to the term tippet-de-witchet which derives from tippet and witchet (archaic term for vagina). [12] [13] In contrast, the English botanist John Ellis, who gave the plant its scientific name in 1768, wrote that the plant name tippitywichit was an indigenous word from either Cherokee or Catawba. [8] [14] The plant name according to the Handbook of American Indians derives from the Renape word titipiwitshik ("they (leaves) which wind around (or involve)"). [15] [16]

On 2 April 1759, the North Carolina colonial governor, Arthur Dobbs, penned the first written description of the plant in a letter to English botanist Peter Collinson. [17] In the letter he wrote: "We have a kind of Catch Fly Sensitive which closes upon anything that touches it. It grows in Latitude 34 but not in 35. I will try to save the seed here." [14] [18] A year later, Dobbs went into greater detail about the plant in a letter to Collinson dated Brunswick, 24 January 1760. [19] [20] [21]

The great wonder of the vegetable kingdom is a very curious unknown species of Sensitive. It is a dwarf plant. The leaves are like a narrow segment of a sphere, consisting of two parts, like the cap of a spring purse, the concave part outwards, each of which falls back with indented edges (like an iron spring fox-trap) upon anything touching the leaves, or falling between them, they instantly close like a spring trap, and confine any insect or anything that falls between them. It bears a white flower. To this surprising plant I have given the name of Fly trap Sensitive.

This was the first detailed recorded notice of the plant by Europeans. The description was before John Ellis' letter to The London Magazine on 1 September 1768, [8] and his letter to Carl Linnaeus on 23 September 1768, [22] in which he described the plant and proposed its English name Venus's Flytrap and scientific name Dionaea muscipula. [23]

The Venus flytrap is a small plant whose structure can be described as a rosette of four to seven leaves, which arise from a short subterranean stem that is actually a bulb-like object. Each stem reaches a maximum size of about three to ten centimeters, depending on the time of year [24] longer leaves with robust traps are usually formed after flowering. Flytraps that have more than seven leaves are colonies formed by rosettes that have divided beneath the ground.

The leaf blade is divided into two regions: a flat, heart-shaped photosynthesis-capable petiole, and a pair of terminal lobes hinged at the midrib, forming the trap which is the true leaf. The upper surface of these lobes contains red anthocyanin pigments and its edges secrete mucilage. The lobes exhibit rapid plant movements, snapping shut when stimulated by prey. The trapping mechanism is tripped when prey contacts one of the three hair-like trichomes that are found on the upper surface of each of the lobes. The mechanism is so highly specialized that it can distinguish between living prey and non-prey stimuli, such as falling raindrops [25] two trigger hairs must be touched in succession within 20 seconds of each other or one hair touched twice in rapid succession, [25] whereupon the lobes of the trap will snap shut, typically in about one-tenth of a second. [26] The edges of the lobes are fringed by stiff hair-like protrusions or cilia, which mesh together and prevent large prey from escaping. These protrusions, and the trigger hairs (also known as sensitive hairs) are likely homologous with the tentacles found in this plant's close relatives, the sundews. Scientists have concluded that the snap trap evolved from a fly-paper trap similar to that of Drosera. [27]

The holes in the meshwork allow small prey to escape, presumably because the benefit that would be obtained from them would be less than the cost of digesting them. If the prey is too small and escapes, the trap will usually reopen within 12 hours. If the prey moves around in the trap, it tightens and digestion begins more quickly.

Speed of closing can vary depending on the amount of humidity, light, size of prey, and general growing conditions. The speed with which traps close can be used as an indicator of a plant's general health. Venus flytraps are not as humidity-dependent as are some other carnivorous plants, such as Nepenthes, Cephalotus, most Heliamphora, and some Drosera.

The Venus flytrap exhibits variations in petiole shape and length and whether the leaf lies flat on the ground or extends up at an angle of about 40–60 degrees. The four major forms are: 'typica', the most common, with broad decumbent petioles 'erecta', with leaves at a 45-degree angle 'linearis', with narrow petioles and leaves at 45 degrees and 'filiformis', with extremely narrow or linear petioles. Except for 'filiformis', all of these can be stages in leaf production of any plant depending on season (decumbent in summer versus short versus semi-erect in spring), length of photoperiod (long petioles in spring versus short in summer), and intensity of light (wide petioles in low light intensity versus narrow in brighter light). [ citation needed ]

The plant also has a flower on top of a long stem, about 6 inches long. The flower is pollinated from various flying insects such as sweat bees, longhorn beetles and checkered beetles. [28]

Flowering Venus flytrap showing its long flower stem

The species produces small, shiny black seeds


The Venus flytrap is found in nitrogen- and phosphorus-poor environments, such as bogs and wet savannahs. Small in stature and slow-growing, the Venus flytrap tolerates fire well and depends on periodic burning to suppress its competition. [29] Fire suppression threatens its future in the wild. [30] It survives in wet sandy and peaty soils. Although it has been successfully transplanted and grown in many locales around the world, it is native only to the coastal bogs of North and South Carolina in the United States, specifically within a 100-kilometer (60 mi) radius of Wilmington, North Carolina. [31] One such place is North Carolina's Green Swamp. There also appears to be a naturalized population of Venus flytraps in northern Florida as well as an introduced population in western Washington. [32] [33] The nutritional poverty of the soil is the reason it relies on such elaborate traps: insect prey provide the nitrogen for protein formation that the soil cannot. They tolerate mild winters, and Venus flytraps that do not go through a period of winter dormancy will weaken and die after a period of time. [34]

They are full sun plants, usually found only in areas with less than 10% canopy cover. [5] The microhabitat where it thrives is typically sparse with grasses, herbs, sphagnum, and often bare patches where there aren't enough nutrients for noncarnivorous plants to survive, or where fires regularly clear competition and prevent cover from forming. Thus, natural fires are an important part of its habitat, required every 3–5 years in most places for D. muscipula to thrive. After fire, D. muscipula seeds germinate well in ash and sandy soil, with seedlings growing well in the open post-fire conditions. The seeds germinate immediately without a dormant period. [5]


Dionaea muscipula occurs naturally only along the coastal plain of North and South Carolina in the U.S, with all known current sites within 90 km of Wilmington, North Carolina. [35] A 1958 survey of herbaria specimens and old documents found 259 sites where the historical record documented the presence of D. muscipula, within 21 counties in North and South Carolina. [36] As of 2019, it was considered extirpated in North Carolina in the inland counties of Moore, Robeson, and Lenoir, as well as the South Carolina coastal counties of Charleston and Georgetown. Remaining extant populations exist in North Carolina in Beaufort, Craven, Pamlico, Carteret, Jones, Onslow, Duplin, Pender, New Hanover, Brunswick, Columbus, Bladen, Sampson, Cumberland, and Hoke counties, and in South Carolina in Horry county. [35]


A large-scale survey in 2019, conducted by the North Carolina Natural Heritage Program, counted a total of 163,951 individual Venus flytraps in North Carolina and 4,876 in South Carolina, estimating a total of 302,000 individuals remaining in the wild in its native range. [37] This represents a reduction of more than 93% from a 1979 estimate of approximately 4,500,000 individuals. [5] A 1958 study found 259 confirmed extant or historic sites. [36] As of 2016, there were 71 known sites where the plant could be found in the wild. Of these 71 sites, only 20 were classified as having excellent or good long-term viability. [6]

Prey selectivity

Most carnivorous plants selectively feed on specific prey. This selection is due to the available prey and the type of trap used by the organism. With the Venus flytrap, prey is limited to beetles, spiders and other crawling arthropods. The Dionaea diet is 33% ants, 30% spiders, 10% beetles, and 10% grasshoppers, with fewer than 5% flying insects. [38]

Given that Dionaea evolved from an ancestral form of Drosera (carnivorous plants that use a sticky trap instead of a snap trap) the reason for this evolutionary branching becomes clear. Drosera consume smaller, aerial insects, whereas Dionaea consume larger terrestrial bugs. Dionaea are able to extract more nutrients from these larger bugs. This gives Dionaea an evolutionary advantage over their ancestral sticky trap form. [39]

Mechanism of trapping

The Venus flytrap is one of a very small group of plants capable of rapid movement, such as Mimosa pudica, the Telegraph plant, sundews and bladderworts.

The mechanism by which the trap snaps shut involves a complex interaction between elasticity, turgor and growth. The trap only shuts when there have been two stimulations of the trigger hairs this is to avoid inadvertent triggering of the mechanism by dust and other wind-borne debris. In the open, untripped state, the lobes are convex (bent outwards), but in the closed state, the lobes are concave (forming a cavity). It is the rapid flipping of this bistable state that closes the trap, [26] but the mechanism by which this occurs is still poorly understood. When the trigger hairs are stimulated, an action potential (mostly involving calcium ions—see calcium in biology) is generated, which propagates across the lobes and stimulates cells in the lobes and in the midrib between them. [40] [41] [42]

It is hypothesized that there is a threshold of ion buildup for the Venus flytrap to react to stimulation. [43] The acid growth theory states that individual cells in the outer layers of the lobes and midrib rapidly move 1 H + (hydrogen ions) into their cell walls, lowering the pH and loosening the extracellular components, which allows them to swell rapidly by osmosis, thus elongating and changing the shape of the trap lobe. Alternatively, cells in the inner layers of the lobes and midrib may rapidly secrete other ions, allowing water to follow by osmosis, and the cells to collapse. Both of these mechanisms may play a role and have some experimental evidence to support them. [44] [45] Flytraps show an example of memory in plants the plant knows if one of its trigger hairs have been touched, and remembers this for a few seconds. If a second touch occurs during that time frame, the flytrap closes. [46] After closing, the flytrap counts additional stimulations of the trigger hairs, to five total, to start the production of digesting enzymes. [47]


If the prey is unable to escape, it will continue to stimulate the inner surface of the lobes, and this causes a further growth response that forces the edges of the lobes together, eventually sealing the trap hermetically and forming a "stomach" in which digestion occurs. Release of the digestive enzymes is controlled by the hormone jasmonic acid, the same hormone that triggers the release of toxins as an anti-herbivore defense mechanism in non-carnivorous plants. (See Evolution below) [47] [48] Once the digestive glands in the leaf lobes have been activated, digestion is catalysed by hydrolase enzymes secreted by the glands.

Oxidative protein modification is likely to be a pre-digestive mechanism used by Dionaea muscipula. Aqueous leaf extracts have been found to contain quinones such as the naphthoquinone plumbagin that couples to different NADH-dependent diaphorases to produce superoxide and hydrogen peroxide upon autoxidation. [49] Such oxidative modification could rupture animal cell membranes. Plumbagin is known to induce apoptosis, associated with the regulation of the Bcl-2 family of proteins. [50] When the Dionaea extracts were pre-incubated with diaphorases and NADH in the presence of serum albumin (SA), subsequent tryptic digestion of SA was facilitated. [49] Since the secretory glands of Droseraceae contain proteases and possibly other degradative enzymes, it may be that the presence of oxygen-activating redox cofactors function as extracellular pre-digestive oxidants to render membrane-bound proteins of the prey (insects) more susceptible to proteolytic attacks. [49]

Digestion takes about ten days, after which the prey is reduced to a husk of chitin. The trap then reopens, and is ready for reuse. [51]

Carnivory in plants is a very specialized form of foliar feeding, and is an adaptation found in several plants that grow in nutrient-poor soil. Carnivorous traps were naturally selected to allow these organisms to compensate for the nutrient deficiencies of their harsh environments and compensate for the reduced photosynthetic benefit. [52] Phylogenetic studies have shown that carnivory in plants is a common adaptation in habitats with abundant sunlight and water but scarce nutrients. [39] Carnivory has evolved independently six times in the angiosperms based on extant species, with likely many more carnivorous plant lineages now extinct. [53]

The "snap trap" mechanism characteristic of Dionaea is shared with only one other carnivorous plant genus, Aldrovanda. For most of the 20th century, this relationship was thought to be coincidental, more precisely an example of convergent evolution. Some phylogenetic studies even suggested that the closest living relatives of Aldrovanda were the sundews. [54] It was not until 2002 that a molecular evolutionary study, by analyzing combined nuclear and chloroplast DNA sequences, indicated that Dionaea and Aldrovanda were closely related and that the snap trap mechanism evolved only once in a common ancestor of the two genera. [55] [56]

A 2009 study [54] presented evidence for the evolution of snap traps of Dionaea and Aldrovanda from a flypaper trap like Drosera regia, based on molecular data. The molecular and physiological data imply that Dionaea and Aldrovanda snap traps evolved from the flypaper traps of a common ancestor with Drosera. Pre-adaptations to the evolution of snap traps were identified in several species of Drosera, such as rapid leaf and tentacle movement. The model proposes that plant carnivory by snap trap evolved from the flypaper traps, driven by increasing prey size. Bigger prey provides greater nutritional value, but large insects can easily escape the sticky mucilage of flypaper traps the evolution of snap traps would therefore prevent escape and kleptoparasitism (theft of prey captured by the plant before it can derive benefit from it), and would also permit a more complete digestion. [54] [55]

In 2016, a study of the expression of genes in the plant's leaves as they captured and digested prey was published in the journal, Genome Research. The gene activation observed in the leaves of the plants gives support to the hypothesis that the carnivorous mechanisms present in the flytrap are a specially adapted version of mechanisms used by non-carnivorous plants to defend against herbivorous insects. [48] [57] In many non-carnivorous plants, jasmonic acid serves as a signaling molecule for the activation of defense mechanisms, such as the production of hydrolases, which can destroy chitin and other molecular components of insect and microbial pests. [58] In the Venus flytrap, this same molecule has been found to be responsible for the activation of the plant's digestive glands. A few hours after the capture of prey, another set of genes is activated inside the glands, the same set of genes that is active in the roots of other plants, allowing them to absorb nutrients. The use of similar biological pathways in the traps as non-carnivorous plants use for other purposes indicates that somewhere in its evolutionary history, the Venus flytrap repurposed these genes to facilitate carnivory.

Proposed evolutionary history

Carnivorous plants are generally herbaceous, and their traps the result of primary growth. They generally do not form readily fossilizable structures such as thick bark or wood. As a result, there is no fossil evidence of the steps that might link Dionaea and Aldrovanda, or either genus with their common ancestor, Drosera. Nevertheless, it is possible to infer an evolutionary history based on phylogenetic studies of both genera. Researchers have proposed a series of steps that would ultimately result in the complex snap-trap mechanism: [54] [55]

  • Larger insects usually walk over the plant, instead of flying to it, [59] and are more likely to break free from sticky glands alone. Therefore, a plant with wider leaves, like Drosera falconeri, [54] must have adapted to move the trap and its stalks in directions that maximized its chance of capturing and retaining such prey—in this particular case, longitudinally. Once adequately "wrapped", escape would be more difficult. [59]
  • Evolutionary pressure then selected for plants with shorter response time, in a manner similar to Drosera burmannii or Drosera glanduligera. The faster the closing, the less reliant on the flypaper model the plant would be.
  • As the trap became more and more active, the energy required to "wrap" the prey increased. Plants that could somehow differentiate between actual insects and random detritus/rain droplets would have an advantage, thus explaining the specialization of inner tentacles into trigger hairs.
  • Ultimately, as the plant relied more on closing around the insect rather than gluing them to the leaf surface, the tentacles so evident in Drosera would lose their original function altogether, becoming the "teeth" and trigger hairs—an example of natural selection utilizing pre-existing structures for new functions.
  • Completing the transition, the plant eventually developed the depressed digestive glands found inside the trap, rather than using the dews in the stalks, further differentiating it from genus Drosera.

Phylogenetic studies using molecular characters place the emergence of carnivory in the ancestors of Dionaea muscipula to 85.6 million years ago, and the development of the snap-trap in the ancestors of Dionaea and its sister genus Aldrovanda to approximately 48 million years ago. [60]

Plants can be propagated by seed, taking around four to five years to reach maturity. More commonly, they are propagated by clonal division in spring or summer. Venus flytraps can also be propagated in vitro using plant tissue culture. [61] Most Venus flytraps found for sale in nurseries garden centers have been produced using this method, as this is the most cost-effective way to propagate them on a large scale. Regardless of the propagation method used, the plants will live for 20 to 30 years if cultivated in the right conditions. [62]


Venus flytraps are by far the most commonly recognized and cultivated carnivorous plant, and they are frequently sold as houseplants. Various cultivars (cultivated varieties) have come into the market through tissue culture of selected genetic mutations, and these plants are raised in large quantities for commercial markets. The cultivars 'Akai Ryu and 'South West Giant' have gained the Royal Horticultural Society's Award of Garden Merit. [63]

Although widely cultivated for sale as a houseplant, D. muscipula has suffered a significant decline in its population in the wild. The population in its native range is estimated to have decreased 93% since 1979. [5] [37]


The species is under Endangered Species Act review by the U.S. Fish & Wildlife Service. [64] The current review commenced in 2018, after an initial "90-day" review found that action may be warranted. A previous review in 1993 resulted in a determination that the plant was a "Potential candidate without sufficient data on vulnerability". [65] The IUCN Red List classifies the species as "vulnerable". [66] The State of North Carolina lists Dionaea muscipula as a species of "Special Concern–Vulnerable". [67] In 2010, CITES listed it as an Appendix II species. [68] NatureServe classified it as "Imperiled" (G2) in a 2018 review. [69]

The U.S. Fish and Wildlife Service has not indicated a timeline to conclude its current review of Dionaea muscipula. The Endangered Species Act specifies a two-year timeline for a species review. However, the species listing process takes 12.1 years on average. [70]


The Venus flytrap is only found in the wild in a very particular set of conditions, requiring flat land with moist, acidic, nutrient-poor soils that receive full sun and burn frequently in forest fires, and is therefore sensitive to many types of disturbance. [5] A 2011 review identified five categories of threats for the species: agriculture, road-building, biological resource use (poaching and lumber activities), natural systems modifications (drainage and fire suppression), and pollution (fertilizer). [71]

Habitat loss is a major threat to the species. The human population of the coastal Carolinas is rapidly expanding. For example, Brunswick County, North Carolina, which has the largest number of Venus flytrap populations, has seen a 27% increase in its human population from 2010 to 2018. [72] As the population grows, residential and commercial development and road building directly eliminate flytrap habitat, while site preparation that entails ditching and draining can dry out soil in surrounding areas, destroying the viability of the species. [73] [69] Additionally, increased recreational use of natural areas in populated areas directly destroys the plants by crushing or uprooting them. [5]

Fire suppression is another threat to the Venus flytrap. In the absence of regular fires, shrubs and trees encroach, outcompeting the species and leading to local extirpations. [29] [74] D. muscipula requires fire every 3–5 years, and best thrives with annual brush fires. [75] Although flytraps and their seeds are typically killed alongside their competition in fires, seeds from flytraps adjacent to the burnt zone propagate quickly in the ash and full sun conditions that occur post a fire disturbance. [76] Because the mature plants and new seedlings are typically destroyed in the regular fires that are necessary to maintain their habitat, D. muscipula's survival relies upon adequate seed production and dispersal from outside the burnt patches back into the burnt habitat, requiring a critical mass of populations, and exposing the success of any one population to metapopulation dynamics. These dynamics make small, isolated populations particularly vulnerable to extirpation, for if there are no mature plants adjacent to the fire zone, there is no source of seeds post-fire. [5]

Poaching has been another cause of population decline. Harvesting Venus flytraps on public land became illegal in North Carolina in 1958, and since then a legal cultivation industry has formed, growing tens of thousands of flytraps in commercial greenhouses for sale as household plants. Yet in 2016, the NY Times reported that demand for wild plants still exists, which "has led to a 'Venus flytrap crime ring.'" [77] In 2014, the state of North Carolina made Venus flytrap poaching a felony. [78] Since then, several poachers have been charged, with one man receiving 17 months in prison for poaching 970 Venus flytraps, [79] and another man charged with 73 felony counts in 2019. [80] Poachers may do greater harm to the wild populations than a simple count of individuals taken would indicate, as they may selectively harvest the largest plants at a site, which have more flowers and fruit and therefore generate more seeds than smaller plants. [5]

Additionally, the species is particularly vulnerable to catastrophic climate events. Most Venus flytrap sites are only 2–4 meters (6.5 –13 feet) above sea level and are located in a region prone to hurricanes, making storm surges and rising sea levels a long-term threat. [5]

In 2005, the Venus flytrap was designated as the state carnivorous plant of North Carolina. [81]

Venus flytrap extract is available on the market as an herbal remedy, sometimes as the prime ingredient of a patent medicine named "Carnivora". According to the American Cancer Society, these products are promoted in alternative medicine as a treatment for a variety of human ailments including HIV, Crohn's disease and skin cancer, but "available scientific evidence does not support the health claims made for Venus flytrap extract". [82]

Watch the video: Φωτοσύνθεση (February 2023).