(1) Nutrients. The chemical substance that works as a raw material for body building and maintaining its function is termed nutrient.

(2) Micronutrients. These are needed in very small amounts, equal to or less than 0. lmg per gram of dry matter.

(3) Macronutrients. These must be present in plant tissues in concentrations of 1 to 10 mg per gram of dry matter.

(4) Active absorption. It is the movement of ions or molecules against concentration gradient or towards concentration gradient by taking energy directly or indirectly through metabolism.

(5) Passive absorption. It is the movement of minerals from higher concentration to lower concentration by physical processes not involving direct expenditure of energy.

(6) Symplastic pathway. It is the movement of ions across the cytoplasm of cortex, endodermis of pericycle through plasmodesmata.