Micronutrients, often called trace elements, are plant nutrients that are needed in small quantities for proper plant growth and yield. They include zinc, boron, manganese, copper, iron, molybdenum and chlorine. While plants need micronutrients in smaller amounts compared to macronutrients like nitrogen, phosphorus and potassium, they are still essential for various metabolic functions in plants. Lack of even one of these micronutrients can limit crop production.
Role of Zinc in Plant Growth
Zinc plays a key role in various enzymatic reactions involved in metabolism and protein synthesis in plants. It is required for stem elongation, root initiation and development, kernel set in grains and protein production. Zinc deficiency results in stunted plant growth, small leaves with interveinal chlorosis, and reduced yields. Soils high in phosphorus can lead to zinc deficiency as phosphorus binds with zinc making it unavailable to plants. Foliar application of zinc sulphate or chelated zinc fertilizers helps correct zinc deficiency in crops.
Importance of Boron for Plant Metabolism
Boron is essential for pollen tube growth, fruit and seed development. It is involved in sugar transport and nitrogen metabolism. Micronutrients Fertilizers boron deficiency causes cracking and hollowness in stems of crops like broccoli and cauliflower. Leaves develop necrosis between veins with curly borders. Oilseed and legume crops are particularly sensitive to boron deficiency. Soils that are sandy, acidic or alkaline tend to be deficient in boron. Boron fertilizers like boric acid and borax are commonly used to supplement boron in deficient soils.
Role of Manganese in Photosynthesis
Manganese acts as a cofactor for various enzymatic reactions like photosynthesis and respiration in plants. It plays an important role in oxidation-reduction reactions and production of chlorophyll pigment. Manganese deficiency reduces photosynthesis resulting in interveinal chlorosis in young leaves. Poor growth and lint/boll production is seen in cotton under manganese deficiency. Soils high in organic matter or phosphorus levels can induce manganese deficiency. Manganese sulfate is commonly used as a fertilizer to correct manganese deficiency.
Copper’s Role in Plant Metabolism
Copper is involved in photosynthesis, respiration, and production of lignin. It aids in oxygen utilization and electron transport during respiration. Copper deficiency causes dieback of shoot tips, leaves developing yellowish-green coloration and roots developing root rot. Legumes and cucurbits are very sensitive to copper deficiency. Acidic and alkaline soils have reduced copper availability. Copper chelates or copper sulfate are used as fertilizers for copper deficient soils to boost crop yields.
Iron – A Key Player in Chlorophyll Synthesis
Iron plays an important role in chlorophyll synthesis and is essential for photosynthesis. Iron deficiency leads to interveinal chlorosis initially in young tender leaves as iron is immobile within the plant. Severe deficiency causes complete whitening of leaves. Iron chelated fertilizers like FeEDTA and FeDTPA are commonly used to treat iron deficiency. Application of farmyard manure also improves iron availability in acidic soils. Improving soil drainage and reducing waterlogging helps in availability of iron to crops.
Molybdenum’s Role in Nitrogen Fixation
Molybdenum acts as a cofactor for the enzyme nitrogenase which is required for biological nitrogen fixation in legumes. It is also involved in nitrate reduction process. Molybdenum deficiency results in stunted growth and chlorosis of leaves in legumes. Oilseed brassicas are also sensitive to molybdenum deficiency. Most soils contain adequate amounts of molybdenum. However, highly leached sandy soils may become deficient. Sodium molybdate is used as molybdenum fertilizer for deficient crops and pastures.
Benefits of Optimum Micronutrient Nutrition
Application of micronutrient fertilizers helps in boosting crop yields manifolds by ensuring optimum crop growth. It leads to improved biomass production, flowering, fruit and seed set. Better micronutrient nutrition enhances drought and disease resistance in crops. It also aids in production of chlorophyll, proteins and other metabolites essential for plant metabolism. Maintaining adequate levels of all micronutrients helps realize the genetic yield potential of crops. Integrated micronutrient management involving soil and foliar application maximizes economic returns from crops.
Micronutrients fertilizers micronutrients though required in small amounts, play a very important role in various physiological and biochemical processes inside plants. Lack of even one micronutrient can adversely impact crop yields. Periodic soil testing helps identify micronutrient deficiencies, which can then be corrected by application of suitable fertilizers. An integrated approach involving balanced fertilization with macronutrients and micronutrients ensures efficient nutrient uptake and utilization by crops for higher productivity.
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