Question

what will happen if we donot provide micronutrients to the plants

Answer 1

Most of the micronutrients have been found to be essential for the plant. E.g. Boron has a role in cell wall formation while copper is necessary for carbohydrate and nitrogen metabolism. If a plant lacks a micronutrient like copper, then this will lead to retarded growth of the plant. Lack of iron leads to chlorosis of the plant (leaf yellowing due to lack of chlorophyll).