Effect of Defoliation on the Growth and Yield of Wheat

The effect of removal of the fifth (L₁), fifth and sixth (L₂) and fifth, sixth and seventh leaves (L₃) from the main shoot and of similar number of leaves from the primary and secondary tillers, on the growth and yield of two varieties of wheat, was investigated. The plants were grown in pots under natural conditions. Defoliation did not affect tillering, ear number, and number of spikelets per ear. The area of the last 3 leaves was reduced only in L₃. Defoliation reduced the growth of stem up to the flag leaf stage but thereafter there was a remarkable recovery in increase in height and dry weight. The grain yield of the main shoot was affected relatively more than that of the primary and secondary tillers by defoliation. The grain yield per plant was reduced by 5 per cent in L₁, and L₂ and by 11 per cent in L₃. The bearing of these observations on productivity per unit area is indicated and it is suggested that a plant with two fewer leaves per shoot may suffer less from mutual shading of leaves and hence prove more efficient in a dense community.