Influence of defoliation during reproductive stage on seed yield in uniculm mungbean plants

An experiment was conducted at the pot yard of Bangladesh Institute of Nuclear Agriculture, Mymensingh during the period from February to May 2018 to investigate the effect of defoliations on morphological characters, yield attributes and yield of uniculm mungbean plant. The experiment comprised of nine levels of defoliation viz., control, 2, 3, 4, 5 leaves removal from base and 2, 3, 4 and 5 leaves removal from top out of 7 leaves during flowering start phase. The morpho-physiological characters such as plant height, stem diameter, leaf area and total dry mass plant-1 and number of racemes, reproductive characters such as rachis length and diameter, number of flowers plant-1 and reproductive efficiency, yield contributing characters such as number of pods plant-1, pod length, number of seeds pod-1, single pod and 100-seed weight and seed yield decreased with increasing defoliation both from base and top except basal 2 leaves defoliation. The above parameters increased over control in basal 2 leaves defoliation. The decrement due to defoliation was greater in top defoliated plants than the corresponding basal defoliated ones indicating upper leaves contributes more assimilate to the sink than the basal leaves. The highest morpho-physiological parameters, reproductive characters and yield contributing characters observed in basal 2 leaves defoliated plants which resulted the highest seed yield (5.75 g plant-1) followed by control (5.49 g plant-1). The lowest morpho-physiological parameters, reproductive and yield contributing characters recorded in top 5 defoliated plants and produced the lowest seed yield (1.21 g plant-1). These results suggest that uniculm mungbean plant tolerate basal 2 leaves loss in the canopy during reproductive stage.