Plant nutrition 435335 224274898 2008-07-08T02:57:37Z Paleorthid 125638 /* See also */ +[[Macronutrients]] {{sync|Fertilizer}} '''Plant nutrition''' is the study of the [[chemical element|chemical elements]] that are necessary for plant growth. There are several principles that apply to plant nutrition. Some elements are essential, meaning that the absence of a given mineral element will cause the plant to fail to complete its [[biological life cycle|life cycle]]; that the element cannot be replaced by the presence of another element; and that the element is directly involved in plant [[metabolism]] (Arnon and Stout, 1939). However, this principle does not leave any room for the so-called beneficial elements, whose presence, while not required, has clear positive effects on plant growth. Plants require specific elements for growth and, in some cases, for reproduction. Major nutrients include: *C = [[Carbon]] 450,000 [[Parts per million|ppm]] *H = [[Hydrogen]] 60,000 ppm *O = [[Oxygen]] 450,000 ppm *P = [[Phosphorus]] 2,000 ppm *K = [[Potassium]] 10,000 ppm *N = [[Nitrogen]] 15,000 ppm *S = [[Sulfur]] 1,000 ppm *Ca = [[Calcium]] 5,000 ppm *Mg = [[Magnesium]] 2000 ppm Minor Nutrients: *Fe = [[Iron]] 100 ppm <br> *Mo = [[Molybdenum]] 0.1 ppm <br> *B = [[Boron]] 20 ppm <br> *Cu = [[Copper]] 6 ppm <br> *Mn = [[Manganese]] 50 ppm <br> *Zn = [[Zinc]] 20 ppm <br> *Cl = [[Chlorine]] 100 ppm <br> These nutrients are further divided into the mobile and immobile nutrients. A plant will always supply more nutrients to its younger leaves than its older ones, so when nutrients are mobile, the lack of nutrients is first visible on older leaves. When a nutrient is less mobile, the younger leaves suffer because the nutrient does not move up to them but stays lower in the older leaves. Nitrogen, phosphorus, and potassium are mobile nutrients, while the others have varying degrees of mobility. Concentration of ppm (parts per million) represents the dry weight of a representative plant. ==Functions of essential nutrients== Each of these nutrients is used in a different place for a different essential function. === Carbon === :Carbon is what most of the plant is made of. It forms the backbone of many plant [[biomolecule]]s, including [[starch]]es and [[cellulose]]. Carbon is fixed through [[photosynthesis]] from the [[carbon dioxide]] in the air and is a part of the carbohydrates that store energy in the plant. === Hydrogen === :Hydrogen also is necessary for building sugars and building the plant. It is obtained from air and liquid water. === Oxygen === :Oxygen is necessary for [[cellular respiration]]. Cellular respiration is the process of generating energy-rich [[adenosine triphosphate]] (ATP) via the consumption of sugars made in photosynthesis. Oxygen gas is produced as a by-product from this reaction. === Phosphorus === :Phosphorus is important in plant [[Biological thermodynamics|bioenergetics]]. As a component of ATP, 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 [[phosphorylation]], and can be used for [[cell signalling]]. Since ATP can be used for the [[biosynthesis]] of many plant [[biomolecule]]s, phosphorus is important for plant growth and [[flower]]/[[seed]] formation. === Potassium === :Potassium regulates the opening and closing of the [[stomata|stoma]] by a potassium ion pump. Since stomata are important in water regulation, potassium reduces water loss from the leaves and increases [[drought]] tolerance. [[Potassium deficiency (plants)|Potassium deficiency]] may cause necrosis or interveinal chlorosis. === Nitrogen === :Nitrogen is an essential component of all proteins, and as a part of [[DNA]], it is essential for growth and reproduction as well. [[Nitrogen deficiency]] most often results in stunting. === Sulphur === :Sulfur produces energy in plants, which is important to growth. === Calcium === :Calcium regulates transport of other nutrients into the plant and is also involved in the activation of certain plant enzymes. [[Calcium deficiency (plant disorder)|Calcium deficiency]] results in stunting. === Magnesium === :Magnesium is an important part of [[chlorophyll]], a critical plant [[pigment]] important in photosynthesis. It is important in the production of [[Adenosine triphosphate|ATP]] through its role as an enzyme [[Cofactor (biochemistry)|cofactor]]. There are many other biological roles for magnesium-- see ''[[Magnesium in biological systems]]'' for more information. [[Magnesium deficiency]] can result in interveinal [[chlorosis]]. === Iron === :Iron is necessary for photosynthesis and is present as an enzyme cofactor in plants. [[Iron deficiency (plant disorder)|Iron deficiency]] can result in interveinal [[chlorosis]] and [[necrosis]]. === Molybdenum === : Molybdenum is a cofactor to enzymes important in building amino acids. === Boron === :Boron is important in sugar transport, [[cell division]], and synthesizing certain enzymes. [[Boron deficiency]] causes necrosis in young leaves and stunting. === Copper === :Copper is important for photosynthesis. Symptoms for copper deficiency include chlorosis. === Manganese === :Manganese is necessary for building the [[chloroplast]]s. [[Manganese deficiency]] may result in coloration abnormalities, such as discolored spots on the [[foliage]]. === Zinc === :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 === :Nickel is required in a [[nitrogen metabolism]], however the requirement is vague in all but a very few select plants. Additional elements include [[silicon]], also used only in a few select plants. [[Cobalt]] has proven to be beneficial to at least some plants, but is essential in others, such as [[legume|legumes]] where it is required for [[nitrogen fixation]]. [[Vanadium]] may be required by some plants, but at very low concentrations. It may also be substituting for molybdenum. [[Selenium]] and [[sodium]] may also be beneficial. Sodium can replace potassium's regulation of stomatal opening and closing. 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 [[cloning|clone]]. Elements present at low levels may demonstrate deficiency, and toxicity is possible at levels that are too high. Further, deficiency of one element may present as symptoms of toxicity from another element, and vice-versa. Carbon and oxygen are absorbed from the air, while other nutrients are absorbed from the soil. Green plants obtain their carbohydrate supply from the carbon dioxide in the air by the process of [[photosynthesis]]. ==See also== *[[Dietary mineral]] *[[Fertilizer]] *[[Macronutrients]] *[[Micronutrients]] [[Category:Botany]] [[Category:Edaphology]] [[Category:Biology and pharmacology of chemical elements]] == External links == * [http://www.tandf.co.uk/journals/titles/01904167.asp ''Journal of Plant Nutrition''] {{PlantMineralDeficiency}} [[da:Næringsstof (plantenæring)]] [[de:Nährstoff (Pflanze)]] [[fr:Nutrition végétale]] [[pl:Składniki pokarmowe]] [[sk:Minerálna výživa]]