EFFECT OF DEFOLIATION DURING REPRODUCTIVE STAGE ON YIELD IN MUNGBEAN (Vigna radiata Wilczek)

Pot experiments were conducted at the pot yard of Bangladesh Institute of Nuclear Agriculture, Mymensingh, Bangladesh, during the period, February to May 2007 and 2008 to investigate the effect of defoliations on morphological characters, yield and yield attributing characters in mungbean. Experiment consisted of nine defoliation treatments viz., control, 2, 3, 4, 5 leaves removal from base and from top out of 7 leaves, during flowering stage. Results showed that plant height, leaf area and total dry biomass plant(-1), number of raceme bearing nodes plant(-1), rachis length, number of flowers plant(-1), reproductive efficiency, number of pods plant(-1), pod length, number of seeds pod(-1), single pod weight, 100-seed weight and seed yield were decreased with increasing defoliation both from the base and top except the basal two leaves defoliation. But the decrement of seed yield was not significant up to basal three leaves defoliation. Contrarily, all these traits increased over the control in basal two leaves defoliation. The decrement due to defoliation was greater in top defoliation than the basal defoliation. These results indicate that upper leaves contributes more assimilate to the sink than the basal leaves. The basal two leaves defoliated plants produced the highest seed yield (5.85 g plant(-1)) due to greater morpho-physiological, reproductive and yield contributing characters whereas the lowest in top five leaves defoliated plants that produced the lowest seed yield (1.05 g plant(-1)).