MINERAL NUTRITION Plant Physiology 2011

Macronutrients

Nitrogen Source: The chief source is the soil. Plants absorbs it either in the form of nitrate or ammoniacal salts. Some bacteria and heterocysts containing blue green algae fix the nitrogen of the atmosphere. Functions: Nitrogen is an essential constituent of different proteins and nucleic acids

Deficiency: The chlorotic symptoms in leaf. A light red cast can also be seen on the veins and petioles. The older mature leaves gradually change from their normal characteristic green appearance to a much paler green. As the deficiency progresses these older leaves become uniformly yellow (chlorotic). Branching is reduced in nitrogen deficient plants resulting in short, spindly plants. The yellowing in nitrogen deficiency is uniform over the entire leaf including the veins. In some plants the underside of the leaves and/or the petioles and midribs develop traces of a reddish or purple color.

Nitrogen

Sulfur. Source: Sulphur is available to plants in the form of soluble sulphate of soil. Fuction: Sulphur is the constituent of amino acids ( cystein and methionine), vitamin (B1), co-enzyme A and volatile oils. The characteristic odour of crucifer plants, onions, garlic and tropeolae is due to sulphur as a constituent of volatile oils. Sulphur affects an increase in nodule formation in root of leguminous plants. Sulphur adversely affects chlorophyll synthesis.

Deficiency symptoms leaves show a general overall chlorosis while still retaining some green color. The veins and petioles show a very distinct reddish color. sulfur deficiency are very similar to the chlorosis found in nitrogen deficiency. However, in sulfur deficiency the yellowing is much more uniform over the entire plant including young leaves. The reddish color often found on the underside of the leaves and the petioles has a more pinkish tone and is much less vivid than that found in nitrogen deficiency. with advanced sulfur deficiency brown lesions and/or necrotic spots often develop along the petiole, and the leaves tend to become more erect and often twisted and brittle.

Sulphur deficiency

Phosphorus Source: as H3PO4 and HPO4. Functions. It promotes healthy root growth and fruit ripening by helping translocation of carbohydrates. It is an essential participating in the skeleton of plasma membrane, nucleic acids, many coenzymes and organic molecules such as ATP and other phosphorylated products. It plays an important role in the energy transfer reaction and in oxidation reduction process.

Deficiency symptoms Phosphorus-deficient leaves show some necrotic spots. A major visual symptom is that the plants are dwarfed or stunted. Some species such as tomato, lettuce, corn and the brassica develop a distinct purpling of the stem, petiole and the under sides of the leaves. Under severe deficiency conditions there is also a tendency for leaves to develop a blue-gray luster. In older leaves under very severe deficiency conditions a brown netted veining of the leaves may develop.

Phosphorous

Calcium. Source. derived from stone or chalk rock contains a larger percentage of calcium carbonate. Function: Calcium is the chief constituents of plants as calcium pectate of the middle lamella of the cell wall. It provides a base for the neutralization of organic acid and is also concerned with the growing root apices. It also acts as an activator of ATPase, some kinase, phospholipids and succinate dehydrogenase. It is essential for fat metabolism. formation of membrane, carbohydrate metabolism, nitrate assimilation, binding of nucleic acids with proteins.

Deficiency symptoms Calcium-deficient leaves show necrosis around the base of the leaves. Classic symptoms of calcium deficiency include blossom-end rot of tomato (burning of the end part of tomato fruits), tip burn of lettuce and death of the growing regions in many plants. All these symptoms show soft dead necrotic tissue at rapidly growing areas, which is generally related to poor translocation of calcium to the tissue.

Calcium

Potassium Source: potassium is widely distributed in soil minerals. Functions. Its utilisation in plant is concerned with enzyme action synthesis of nucleic acid and chlorophyll oxidative and photophosphorylation translocation of solutes etc.

Deficiency symptoms potassium Leaves show marginal necrosis (tip burn), others at a more advanced deficiency status show necrosis in the interveinal spaces between the main veins along with interveinal chlorosis. The onset of potassium deficiency is generally characterized by a marginal chlorosis progressing into a dry leathery tan scorch on recently matured leaves.

Potassium

Magnesium Source : magnesium occurs as carbonate fairly similar to that of calcium Functions. It is a constituent of chlorophyll and, therefore, essential for the formation of this pigment. It acts as a phosphorous carrier in the plant, particularly in connection with the formation of seeds of high oil contents which contain compound lecithin. Magnesium is essential for the synthesis of fats and metabolism of carbohydrates and phosphorous. It is required to combine two subunits of ribosomes.

Magnesium The Mg deficient leaves show advanced interveinal chlorosis, with necrosis developing in the highly chlorotic tissue. In its advanced form, magnesium deficiency may superficially resemble potassium deficiency. In the case of magnesium deficiency the symptoms generally start with mottled chlorotic areas developing in the interveinal tissue. The interveinal laminae tissue tends to expand proportionately more than the other leaf tissues, producing a raised puckered surface, with the top of the puckers progressively going from chlorotic to necrotic tissue

Magnesium

Microelements

Iron Source: It is fairly present in the form of its oxides giving red or brown colour to the soil. In well-irrigated areas ferric compounds are predominantly found and in water logged soils, ferrous compounds are formed. Functions: Iron also acts as a catalyst and electron carrier in respiration. Iron is a constituent of cytochromes, ferredoxin, catalase, peroxidase and etc. It also acts as an activator of nitrate reductase and aconitase.

Deficiency symptoms These iron-deficient leaves show strong chlorosis at the base of the leaves with some green netting. The most common symptom for iron deficiency starts out as an interveinal chlorosis of the youngest leaves, evolves into an overall chlorosis, and ends as a totally bleached leaf. The bleached areas often develop necrotic spots

Iron

Manganese. Source: Like iron, the oxide forms of manganese are common in soil but the more highly oxidised form ( manganese dioxide) are of very low availability to plants. Functions: It acts as an activator of some oxidases, peroxidises, dehydrogenases, kinases and decarboxylases etc. And is essential for the formation of chlorophyll. It also decreases the solubility of iron by oxidation hence in certain cases abundance of manganese leads to iron deficiency in plants.

Deficiency symptoms In leaves light interveinal chlorosis developed under a limited supply of Mn. The early stages of the chlorosis induced by manganese deficiency are somewhat similar to iron deficiency. As the stress increases, the leaves take on a gray metallic sheen and develop dark freckled and necrotic areas along the veins. A purplish luster may also develop on the upper surface of the leaves.

Manganese

Copper Source: Copper is found in small quantities in soils Functions: Its specific function in plants largely remains to be determined but its role as a catalyst and regulator is quite evident. It is a constituent of ascorbic acid oxidase, laccase, tryosinase, phenoloxidase, plastocyanin etc. And is essential for photosynthesis, respiration and carbohydrate/nitrogen balance.

Deficiency symptoms copper-deficient leaves are curled, and their petioles bend downward. Copper deficiency may be expressed as a light overall chlorosis along with the permanent loss of turgor in the young leaves. Recently matured leaves show netted, green veining with areas bleaching to a whitish gray. Some leaves develop sunken necrotic spots and have a tendency to bend downward. Trees under chronic copper deficiency develop a rosette form of growth. Leaves are small and chlorotic with spotty necrosis.

Copper

zinc Source Like copper, it is also found in soils in very small quantities and largely results from concentration and addition from growing plants and added residue. Functions. little is known about its function like that of iron, manganese or copper but it is a component of enzymes like carbonic anhydrogenase, alcohol dehydrogenase, Lactic acid dehydrogenase, glutamic dehydrogenase, alkaline phosphatise, carboxypeptidase, etc. It has been found essential for carbon dioxide evolution and utilization, carbohydrate and phosphorous metabolism and synthesis of RNA and auxins. A close relationship is found between zinc and chlorophyll formation.

Deficiency symptoms Leaves show an advanced case of interveinal necrosis. In the early stages of zinc deficiency the younger leaves become yellow and pitting develops in the interveinal upper surfaces of the mature leaves. Guttation is also prevalent. As the deficiency progress these symptoms develop into an intense interveinal necrosis

zinc

Molybdenum Source: It is found widely distributed in small amounts in soils and plants its higher concentration occurs in mineral oils and coal ashes. Functions: It is an important constituent of the nitrate reducatse system. It also acts as an activator of some dehydrogenase and phosphatase and as cofactors in the synthesis of ascorbic acid. It is found necessary to the nodule formation in legumes for the fixation of atmospheric nitrogen.

Molybdenum. leaves show some mottled spotting along with some interveinal chlorosis. In the case of cauliflower, the lamina of the new leaves fail to develop, resulting in a characteristic whiptail appearance. In many plants there is an upward cupping of the leaves and mottled spots developing into large interveinal chlorotic areas under severe deficiency. At high concentrations, molybdenum has a very distinctive toxicity symptom in that the leaves turn a very brilliant orange.

Molybdenum

Boron Source. Boron occurs in rocks and marine sediments. It is absorbed in the form of borate ions. Function. It is necessary for translocation of sugars is involved in the reproduction and germination of pollens. It is concerned with water reactions in cells and regulate the intake of water into the cell.

Deficiency symptom boron-deficient leaves show a light general chlorosis.

Deficiency symptoms

Deficiency symptoms of Chloride leaves have abnormal shapes, with distinct interveinal chlorosis. The most common symptoms of chlorine deficiency are chlorosis and wilting of the young leaves. The chlorosis occurs on smooth flat depressions in the interveinal area of the leaf blade. In more advanced cases there often appears a characteristic bronzing on the upper side of the mature leaves.

Chloride

Reference Lincoln Taiz and Eduardo Zeiger, Plant Physiology, Fifth Edition.