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It is the study of the
that are necessary for plant growth, and also of their external supply and internal metabolism. In 1972, E. Epstein defined two criteria for an element to be essential for plant growth:
in its absence the plant is unable to complete or
that the element is part of some essential plant constituent or metabolite.
This is in accordance with . There are 14 essential plant nutrients. Carbon and oxygen are absorbed from the air, while other nutrients including water are typically obtained from the soil (exceptions include some
plants). Plants must obtain the following mineral nutrients from the growing media:
the primary macronutrients: nitrogen (N), phosphorus (P), potassium (K)
the three secondary macronutrients: calcium (Ca), sulfur (S), magnesium (Mg)
the micronutrients/trace minerals: boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu),
(Mo), nickel (Ni)
The macronutrients are consumed in larger quantities and are present in plant tissue in quantities from 0.2% to 4.0% (on a dry matter weight basis). Micro nutrients are present in plant tissue in quantities measured in parts per million, ranging from 5 to 200 ppm, or less than 0.02% dry weight.
Most soil conditions across the world can provide plants with adequate nutrition and do not require fertilizer for a complete life cycle. However, humans can artificially modify soil through the addition of
to promote vigorous growth and increase yield. The plants are able to obtain their required nutrients from the fertilizer added to the soil. A colloidal carbonaceous residue, known as , can serve as a nutrient reservoir. Even with adequate water and sunshine,
can limit growth.
Nutrient uptake from the soil is achieved by , where
(H+) into the soil through . These hydrogen ions displace
attached to negatively charged soil particles so that the cations are available for uptake by the root.
Plant nutrition is a difficult subject to understand completely, partly because of the variation between different plants and even between different species or individuals of a given . An element present at a low level may cause deficiency symptoms, while the same element at a higher level may cause toxicity. Further, deficiency of one element may present as symptoms of toxicity from another element. An abundance of one nutrient may cause a deficiency of another nutrient. For example, lower availability of a given nutrient such as SO42- can affect the uptake of another nutrient, such as NO3-. As another example, K+ uptake can be influenced by the amount of NH4+ available.
The , especially the root hair, is the most 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
in order for the nutrients to reach the conducting tissues, xylem and phloem. The , a cell wall outside of the stele but within the root, prevents passive flow of water and nutrients, helping to regulate the uptake of nutrients and water.
moves water and inorganic molecules within the plant and
accounts for organic molecule transportation.
plays a key role in a plants 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 co this requires an energy source, usually ATP, to power molecular pumps that move the ions or molecules through the membrane.
Nutrients are moved inside a plant 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, 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
with microorganisms. Two important types of these relationship are
with bacteria such as , that carry out , in which atmospheric
(N2) is converted into
(NH4); and
with , 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.
Though nitrogen is plentiful in the Earth's atmosphere, relatively few plants harbor nitrogen fixing bacteria, so most plants rely on nitrogen compounds present in the soil to support their growth. These can be supplied by
or added plant residues, nitrogen fixing bacteria, animal waste, or through the application of .
, 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 solution, is the , developed by D. R. Hoagland in 1933, the solution consists of all the essential nutrients in the correct proportions necessary for most plant growth. An aerator is used to prevent an
event or hypoxia.
can affect nutrient uptake of a plant because without oxygen present, respiration becomes inhibited within the root cells. The
is a variation of hydroponic technique. The roots are not fully submerged, which 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.
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.
Further information:
At least 17 elements are known to be essential nutrients for plants. In relatively large amounts, the soil supplies nitrogen, phosphorus, potassium, calcium, magnesium, these are often called the . In relatively small amounts, the
supplies iron, manganese, boron, molybdenum, copper, zinc, chlorine, and cobalt, the so-called . 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.
Although nitrogen is plentiful in the Earth's atmosphere, relatively few plants engage in
(conversion of atmospheric nitrogen to a biologically useful form). Most plants therefore 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.
obtain their carbohydrate supply from the carbon dioxide in the air by the process of . Each of these nutrients is used in a different place for a different essential function.
forms the backbone of many plants , including
in the air and is a part of the
that store energy in the plant.
also 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.
by itself or in the molecules of H2O or CO2 are necessary for plant . Cellular respiration is the process of generating energy-rich
(ATP) via the consumption of sugars made in photosynthesis. Plants produce oxygen gas during photosynthesis to produce glucose but then require oxygen to undergo aerobic
and break down this glucose and produce ATP.
Further information:
Further information:
Like nitrogen,
is closely concerned with many vital plant processes. It is present mainly as a structural component of the ,
(RNA), and as a constituent of fatty , of importance in membrane development and function. It is present in both organic and inorganic forms, both of which are readily translocated. All energy transfers in the cell are critically dependent on phosphorus. As a component of , phosphorus is needed for the conversion of light energy to chemical energy (ATP) during photosynthesis. Phosphorus can also be used to modify the activity of various enzymes by , and can be used for . Since ATP can be used for the
of many plant , phosphorus is important for plant growth and / formation. Phosphate esters make up DNA, RNA, and phospholipids. Most common in the form of polyprotic phosphoric acid (H3PO4) in soil, but it is taken up most readily in the form of H2PO4. Phosphorus is limited in most soils because it is released very slowly from insoluble phosphates. Under most environmental conditions it is the limiting element because of its small concentration in soil and high demand by plants and microorganisms. Plants can increase phosphorus uptake by a mutualism with mycorrhiza. A
in plants is characterized by an intense green coloration in leaves. If the plant is experiencing high phosphorus deficiencies the leaves may become denatured and show signs of necrosis. Occasionally the leaves may appear purple from an accumulation of . Because phosphorus is a mobile nutrient, older leaves will show the first signs of deficiency.
On some , the phosphorus nutrition of some , including the spruces, depends on the ability of
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 greening of foliage and the development of vigorous shoot growth.
can produce symptoms similar to those of nitrogen deficiency (Black 1957), but, as noted by Russell (1961): “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
seedlings, for Benzian (1965) 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 an at 0.62 ppm, only the smallest seedli and at 6.2 ppm, the “low phosphorus” treatment, seedlings were of good size and color (Swan 1960b). Swan (1962)
It is useful to apply a high phosphorus content fertilizer, such as bone meal, to perennials to help with successful root formation.
Unlike other major elements,
does not enter into the composition of any of the important plant constituents involved in metabolism (Swan 1971a), but it does occur in all parts of plants in substantial amounts. 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
and , 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 , especially under low light intensity.
potassium levels are high, plants take up more potassium than needed for healthy growth. The term luxury consumption has been applied to this. 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 a reduced growth in impaired
and reduced needle length (Heiberg and White 1951). A relationship between potassium nutrition and cold resistance has been found in several tree species, including 2 species of spruce (Sato and Muto 1951).
regulates the opening and closing of the
by a potassium ion pump. Since stomata are important in water regulation, potassium reduces water loss from the leaves and increases
tolerance.
may cause necrosis or interveinal chlorosis. K+ is highly mobile and can aid in balancing the anion charges within the plant. Potassium helps in fruit colouration, shape and also increases its brix. Hence, quality fruits are produced in Potassium rich soils. It also has high solubility in water and leaches out of rocky or sandy soils. This water solubility can result in potassium deficiency. Potassium serves as an activator of enzymes used in photosynthesis and respiration Potassium is used to build cellulose and aids in photosynthesis by the formation of a chlorophyll precursor.
may result in higher risk of pathogens, wilting, chlorosis, brown spotting, and higher chances of damage from frost and heat.
Further information:
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 , and it is a constituent of , the building blocks of
(Swan 1971a).
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. Most of the
is from the soil in the forms of NO3-, although in acid environments such as boreal forests where nitrification is less likely to occur, ammonium NH4+ is more likely to be the dominating source of nitrogen. Amino acids and proteins can only be built from NH4+ so NO3- must be reduced. Under many agricultural settings, nitrogen is the limiting nutrient of high growth. Some plants require more nitrogen than others, such as corn (Zea mays). Because nitrogen is mobile, the older leaves exhibit chlorosis and necrosis earlier than the younger leaves. Soluble forms of nitrogen are transported as amines and amides.
The growth of all organisms depends on the availability of mineral nutrients, and none is more important than , which is required in large amounts as an essential component of , , and other cellular constituents, including . Nitrogen is an essential constituent of , but it influences growth and utilization of sugars more than it influences
through a reduction in chlorophyll. There is an abundant supply of nitrogen in the earth’s atmosphere—nearly 79% in the form of N2 gas. However, N2 is unavailable for use by most organisms because there is a triple bond between the 2 nitrogen atoms, making the molecule almost inert. In order for nitrogen to be used for growth it must be “fixed” (combined) in the form of
(NH4) or nitrate (NO3) 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
production in all environments where there is suitable climate and availability of water to support life.
Nitrogen enters the plant largely through the . 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 favours protein breakdown accompanied by high
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 te 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 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).
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 these bacteria are either free-living or form
associations with plants or other organisms (e.g., termites, protozoa), while other bacteria bring about transformations of
to , and of nitrate to N2 or other nitrogen gases. Many
degrade organic matter, releasing fixed nitrogen for reuse by other organisms. All these processes contribute to the .
is a structural component of some amino acids and vitamins, and is essential in the manufacturing of . Sulphur is also found in the Iron Sulphur complexes of the electron transport chains in photosynthesis. It is immobile and deficiency therefore affects younger tissues first. Symptoms of deficiency include yellowing of leaves and stunted growth.
regulates transport of other nutrients into the plant and is also involved in the activation of certain plant enzymes.
results in stunting. This nutrient is involved in photosynthesis and plant structure.
is also a result of inadequate calcium.
Calcium in plants occurs chiefly in the , with lower concentrations in seeds, fruits, and roots. A main 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 , 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 neutralizat inhibition of some potassium- and a role in nitrogen absorption. A notable feature of calcium-deficient plants is a defective root system.
causes stunting of root systems (Russell 1961). Roots are usually affected before above-ground parts (Chapman 1966).
Calcium deficiency appears to have 2 main effects on plants: (1) stunting of the root system, and (2) a “fairly characteristic” effect on the visual appearance of leaves (Russell 1961). Roots are usually affected before above-ground parts (Chapman 1966).
Main article:
The outstanding role of
in plant nutrition is as a constituent of the
molecule. As a carrier, it is also concerned in numerous enzyme reactions as an effective activator, in which it is closely associated with energy-supplying
compounds. Magnesium is very mobile in plants, and, like potassium, when
is translocated from older to younger tissues, so that signs of deficiency appear first on the oldest needles and then spread progressively to younger and younger tissues.
Silicon is not considered an essential element for plant growth and development.
In plants,
has been shown in experiments to strengthen , improve plant strength, health, and productivity. There have been studies showing evidence of silicon improving
resistance, decreasing lodging potential and boosting the plant's natural pest and disease fighting systems. Silicon has also been shown to improve plant vigor and physiology by improving root mass and density, and increasing above ground plant
and . 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".
Silicon is the second most abundant element in earth's crust. Higher plants differ characteristically in their capacity to take up silicon. Depending on their SiO2 content they can be divided into three major groups:
Wetland graminae-wetland rice,
(10–15%)[]
Dryland graminae-sugar cane, most of the cereal species and few dicotyledons species (1–3%)[]
Most of dicotyledons especially legumes (&0.5%)[]
The long distance transport of Si in plants is confined to the xylem. Its distribution within the shoot organ is therefore determined by transpiration rate in the organs[]
The epidermal cell walls are impregnated with a film layer of silicon and effective barrier against water loss, cuticular transpiration rate in the organs.[]
Some elements are directly involved in plant
(Arnon and Stout, 1939).[] However, this principle does not account for the so-called beneficial elements, whose presence, while not required, has clear positive effects on plant growth. Mineral elements that either stimulate growth but are not essential, or that are essential only for certain plant species, or under given conditions, are usually defined as beneficial elements.
Plants are able sufficiently to accumulate most trace elements. Some plants are sensitive indicators of the chemical environment in which they grow (Dunn 1991), 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). 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.
Iron is necessary for photosynthesis and is present as an enzyme cofactor in plants.
can result in interveinal
and . 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.
Molybdenum is a cofactor to enzymes important in building amino acids. Involved in Nitrogen metabolism. Mo is part of Nitrate reductase enzyme.
Boron is important for binding of pectins in the RGII region of the primary cell wall, secondary roles may be in sugar transport, , and synthesizing certain enzymes.
causes necrosis in young leaves and stunting.Boron is required for the uptake and utilization of calcium,membrane functioning ,pollen germination,cell elongation,cell differentiation and carbohydrate metabolism.
Copper is important for photosynthesis. Symptoms for copper deficiency include chlorosis. Involved in many enzyme processes. Necessary for proper photosythesis. Involved in the manufacture of lignin (cell walls). Involved in grain production. It is also hard to find in some conditions.
Manganese is necessary for photosynthesis, including the building of .
may result in coloration abnormalities, such as discolored spots on the .
Sodium is involved in the regeneration of
plants. Sodium can potentially replace potassium's regulation of stomatal opening and closing.
Essentiality
Essential for C4 plants rather C3
Substitution of K by Na: Plants can be classified into four groups:
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
Group B—specific growth responses to Na are observed but they are much less distinct
Group C—Only minor substitution is possible and Na has no effect
Group D—No substitution is occurred
Stimulate the growth—increase leaf area, stomata, improve the water balance
Na functions in metabolism
C4 metabolism
Impair the conversion of pyruvate to phosphoenol-pyruva
Reduce the photosystem II activity and ultrastructural changes in mesophyll chloroplast
Replacing K functions
Internal osmoticum
Stomatal function
Photosynthesis
Counteraction in long distance transport
Enzyme activation
Improves the crop quality e.g. improve the taste of carrots by increasing sucrose
Zinc is required in a large number of enzymes and plays an essential role in DNA transcription. A typical symptom of
is the stunted growth of leaves, commonly known as "little leaf" and is caused by the oxidative degradation of the growth hormone .
In , Nickel is absorbed by plants in the form of Ni2+ ion. Nickel is essential for activation of , an enzyme involved with
that is required to process urea. Without Nickel, toxic levels of urea accumulate, leading to the formation of necrotic lesions. In , Nickel activates several enzymes involved in a variety of processes, and can substitute for Zinc and Iron as a cofactor in some enzymes.
Chlorine, as compounded chloride, is it also plays a role in .
Cobalt has proven to be beneficial to at least some plants, but is essential in others, such as
where it is required for
for the symbiotic relationship it has with nitrogen-fixing bacteria.
may be required by some plants, but at very low concentrations. It may also be substituting for .
may also be beneficial.
The requirement of Co for N2 fixation in legumes and non-legumes have been documented clearly
Protein synthesis of Rhizobium is impaired due to Co deficiency
It is still not clear whether Co has direct effect on higher plant
Tea has a high tolerance for Al toxicity and the growth is stimulated by Al application. The possible reason is the prevention of Cu, Mn or P toxicity effects.
There have been reports that Al may serve as fungicide against certain types of .
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.
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 (Ronco 1970).
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Allen V. B D. J. Pilbeam (2007). . CRC Press. pp. 4–.   2010.
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Black, C.A. 1957. Soil-plant relationships. New York, Wiley and Sons. 332 p.
Russell, E.W. 1961. Soil Conditions and Plant Growth, 9th ed. Longmans Green, London, U.K.. 688 p.
Benzian, B. 1965. Experiments on nutrition problems in forest nurseries. U.K. Forestry Commission, London, U.K., Bull. 37. 251 p. (Vol. I) and 265 p. (Vol II).
Swan, H.S.D. 1960b. The mineral nutrition of Canadian pulpwood species. Phase II. Fertilizer pellet field trials. Progress Rep. 1. Pulp Pap. Res. Instit. Can., Montreal QC, Woodlands Res. Index No. 115, Inst. Project IR-W133, Res. Note No. 10. 6 p.
Swan, H.S.D. 1962. The scientific use of fertilizers in forestry. p. 13-24 in La Fertilisation Forestière au Canada. Fonds de Recherches Forestières, Laval Univ., Quebec QC, Bull. 5
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Sato, Y.; Muto, K. 1951. (Factors affecting cold resistance of tree seedlings. II. On the effect of potassium salts.) Hokkaido Univ., Coll. Agric., Coll. Exp. Forests, Res. Bull. 15:81–96.
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Krasowski, M.J.; Owens, J.N. 1999. Tracheids in white spruce seedling’s long lateral roots in response to nitrogen availability. Plant and Soil 217(1/2):215–228.
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(2012). "Nutrient and toxin all at once: How plants absorb the perfect quantity of minerals".
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(5th ed.). Kluwer Academic Publishers.  .
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