Nitrogen is one of the essential macronutrients required by plants and absorbed in the form of nitrates and nitrites. It forms a major constituent of proteins, vitamins, chlorophyll, pyrimidines and hormones. Deficiency of nitrogen of leads to stunted growth, chlorosis, reduced cell division, decrease in protein content, wrinkling of cereal grains, purple coloration of the shoot axis.

Iron is another essential element necessary for plant growth and development. Chlorophyll production requires iron and it is a component of many enzymes which participate in energy transfer, nitrogen fixation, lignification. Iron deficiency is clearly indicated by chlorosis where leaf yellowing appears first in the interveinal regions of the young leaves. Chlorosis referes to production of insufficienct chlorophyll leading to yellowing of the leaves.

Chlorine is absorbed in the form of chloride ions and it helps in maintaining salt balance in cells of plant. Chlorine is important for opening and closing of stomata. Chlorine deficiency results in the wilting of the leaves which later turn in bronze colour.

Boron is another essential element which is required for membrane functioning, pollen germination, cell differentiation. It is also required for calcium uptake and utilization. Boron deficiency symptoms include leaves with yellowish or reddish cast, growing points stop functioning leading to stunted or rosette appearance. Its deficiency also causes formation of cracked fruits.