Mineral Nutrition Test - 3

Essential elements can alter the osmotic potential of a cell. Potassium plays an important role in the opening and closing of stomata.

Plants obtain sulphur in the form of sulphate. Sulphur is present in two amino acids – cysteine and methionine and is the main constituent of several coenzymes, vitamins (thiamine, biotin, Coenzyme A).

Magnesium is macronutrient while all others are micro nutrient.

Sulphur contains amino acid methionine, zinc is important for auxin, chlorophyll contains magnesium and molybdenum take the help of nitrogenase.

Macronutrients are generally present in plant tissues in large amounts (in excess of 10m mole Kg ^–1 of dry matter).

Zn²⁺ also serves as an activator of a group of enzymes: alcohol dehydrogenase, pyridine nucleotide dehydrogenase, carboxypeptidase.

Plants obtain iron in the form of ferric ions (Fe³⁺). It is required in larger amounts in comparison to other micronutrients. It is an important constituent of proteins involved in the transfer of electrons like ferredoxin.

It is absorbed in the form of manganous ions (Mn²⁺). It activates many enzymes involved in photosynthesis, respiration and nitrogen metabolism.

Micronutrients or trace elements, are needed in very small amounts(less than 10 mole Kg ^–1 of dry matter). These include iron, manganese, copper, molybdenum, zinc, boron, chlorine and nickel.

Deficiency of N, K, S and Mo causes stunted growth because of inhibition of cell division. Deficiency of N, S and Mo delays flowering.