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MICRONUTRIENTS IMPORTANCE INCROP NUTRITION"

UTTAM KUMARMaster of Science in Agriculture(Soil Science and Agricultural Chemistry)

28 SEP. 2015

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Micronutrients- An introductionThe world micronutrients represents some essential nutrients that are required very small quantities for the growth of plants and micro-organisms.

There are 17 essential elements for plant growth, out of these elements 8 elements are considered as micronutrients. They are iron (Fe), manganese(Mn), copper(Cu), zinc(Zn), boron(B) molybdenum(Mo), nickel(Ni) and chlorine(Cl).

Out of these micronutrients iron (Fe), manganese(Mn), copper(Cu), zinc(Zn), behave like cations, and boron(B) molybdenum(Mo), and chlorine(Cl) behave like as anion.

So that the chemistry of micro- nutrients cations are different from micro- nutrients anions.

Among these 8 micro- nutrients, the content of iron (Fe) in soil as well as in plants is the highest and sometimes higher than even P and S content.

Micronutrients are also called trace elements, oligo elements or spurn elements.

Major sources of micro-nutrientsS.no.Micro- nutrientsMinerals1.FeHor nblende, Hametite, Goethite, Pyrite, Magnetite, Olivine.2.MnPyrolusite, Maganite, Rhodonite.3.CuChalcopyrite, Covelite, Cuprite, Malachite.4.znSphalarite, Smithsonite,5.BTourmaline, Colemanite, Borex,Kernite.6.ClApatite, Murate of potash, Sodium chloride.7MoMolybdenite, Wulfenite, Ferrimolybdenite.8.NiSerpentine, Olivine

Form of micro-nutrients absorbed by plantsS.No.Micro-nutrientsIonic forms1.FeFe2+, Fe3+2.MnMn2+, Mn4+3.CuCu2+4.ZnZn2+5.BH2BO3-, HBO32-, BO33-, B4O72-6.ClCl-7MoMoO42-8.NiNi2+

Micro-nutrients Essentiality DiscovererS.No.Micro-nutrientsDiscoverer1.FeGriss 18432.MnMcHargue -- 19223.CuA.L.Sommer and C.P. Lipman -- 19314.ZnA.L.Sommer and C.P. Lipman -- 19265.BWarington 19236.ClT.C. Broyer --19547.MoArnon and Stout 19398.NiBrown, Welch, and cary -- 1987

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Micro nutrients amount In soilMicro nutrients RangAverage

Fe0.5 50%3 4%Mn20 3,000 ppm600 ppmCu2 100 ppm9 ppmZn10 300 ppm50 ppmB2 200 ppm50 ppmCl1-100ppm50ppmMo0.2 5.0 ppm1.2 ppmNi2 750 ppm50 ppm

Micro nutrients amount In plantsMicro nutrients Amount In Plants(ppm)Fe100Mn50Cu6Zn20B20Cl100Mo0.1Ni2

iron major function Important constituent of two group of protien- 1.Heme- protein 2. Fe-S protein

Iron is involved in the production of chlorophyll.Oxygen carrier.Nucleic acid metabolism.Chlorophyll synthesis.Protein synthesis.Act as catalyst in N2 Reeducates.Structural component of phorphyrin molecules.Required for nitrogen fixation.

iron deficiency symptomsyounger leaves exhibit interveinal chlorosis. Without dead spot this is the only symptom - IronPlant having 50 ppm (30ppm) Fe, than Fe deficiency will occur.Whole plants turning necrotic.Due to deficiency of Fe- 1. White eye in paddy 2. yellow blotch in citrus. 3.green rating in potato.

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Fe- deficiency in Maize

Soybean

manganese major functionManganese is necessary in photosynthesis, nitrogen metabolism and to form other compounds required for plant metabolism.Important constituent of Suproxide dimutase (Mn-SOD).It take part in electron transport in photosysytem -2. Mn act as enzyme activation, and this enzyme produce amino acid.Deficiency symptoms:-In addition to interveinal chlorosis on young leaves, grey or tan necrotic spots develop in chlorotic areas.Plant containing less than 25 ppm Mn then deficiency symptoms will occur.

Common micro deficiency for soybean and small grains Susceptible soils:High pH (alkaline) soils (>6.8)High organic matter soils (>6%)

Due to Mn deficiency :- 1.gray spack in Oat 2.pahala blight in sugercane. 3.marshy spot in pea. 4.spekeld yellow in beetrot

Grey Speck in Oat

Soybean- compelete intervinal chlorosis.

copper major function Copper is necessary for carbohydrate and nitrogen metabolism.Eletron carrier in oxidation reduction reaction.Utilization of iron in chlorophyll synthesis.Enhance the fertility of mala flower.Enhance disease resistance in plants

Deficiency symptoms:- While younger leaves have interveinal chlorosis, the tips and lobes of leaves remain green followed by veinal chlorosis and rapid, extensive necrosis of leaf blade Due to Deficiency of copper-1.Dai back in citrus.2.Reclamation of rice

zinc major function Zinc is an essential component of three enzymes- 1. carbonic anhydrase. 2.Alcoholic dehydrogenase. 3.Suproxide dismutase. for energy production, protein synthesis, and growth regulation.Important in the synthesis of IAA.Essential for water uptake.Play important role in stablization of protein.

Deficiency symptoms:- Plant containing less than 15 ppm Zn than deficiency symptoms will occur.Intervinal chlorosis first appear in younger leaves.Reduse the size of the leaves- little leaf.Mainly occur in calcareous soils.

Due to Zn deficiency fallowing deficiency symptoms will occur.1. khaira disease in rice.2. white bud in maize.3. little leaf in cotton , chilli, brinjal. Citrus mango. Etc.4.bronzing in Guava.

Tomato

Boron major functionA primary function of boron is related to cell wall formation.Important for pollination and pollen germination.Help in k translocation as well as stomatal opening.Calcium metabolism.Act as regulator of k/Ca ratio.Essential for translocation of sugar. Deficiency symptoms:- Terminal buds die giving rise to a witch's broom. Young leaves become very thick and leathery and chlorotic. Rust-coloured cracks and corking occur on young stems, petioles and flower stalks. Young leaves crinkled.

Common deficiency for alfalfa and other foragesSusceptible soils: Sands and low OM soils, Dry soils.Due to B deficiency fallowing deficiency symptoms will occur.Brown or black heart in beet rotHallow stem in cauliflower.Browning or heart rot in sugarcane.Internal cork in apple.Necrosis in AonlaTop sickness in tobacco.

Rice

Rape

Molybdenum-major functionMo is important constituent of nitrogenase enzyme , which help in N2 fixation in legumes crops.Mo is essential component of NO3- reductase enzymes. this enzyme concerted in chloroplast which catalzes the conversion of NO3- to NO2- protein synthesis and sulfur metabolism are also affected by molybdenum. Molybdenum has a significant effect on pollen formation.Also reported to have an essential role in iron absorption and translocation in plants.

Mo - Deficiency symptoms The deficiency symptoms of Mo is first appear In Older leaves , interveinal chlorosis with some dead spots.Due to Mo deficiency fallowing deficiency symptoms will occur. 1. whip tail in cauliflower. 2. yellow spot in citrus. 3. scald in beans.

Chlorine - FunctionsEssential for stomatal opening.Cl is related to electrical charge balance in physiological functions in plants.It indirectly affects plant growth by stomatal regulation of water loss.

Deficiency symptomshighly branched root systems are the main chloride-deficiency symptoms, which are found mainly in cereal crops.chloride deficiencies have been reported on sandy soils,humid region with high rainfall area.willting and twisting in wheat due to Cl deficiency.

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