Deflowering effect on vasculature and yield attributes in raceme of mungbean ['vigna radiata (L.) Wilczek']

A raceme of mungbean plant generally bears 32-60 flowers but only 3-8 matured pods are borne with the majority of flowers abscise. The experiments were conducted to investigate deflowering effect on podset probability and vasculature in the proximal and distal positions of raceme in mungbean plant. Four deflowering treatments were applied: control (No flower removal), all opened flowers were continuously removed from proximal 1-10, 1-20 and 1-30 nodes of the racemes. The anatomical investigation was made at two positions, basal and distal parts of the rachis of each treatment. Results indicated that mungbean plant compensated for yield loss up to 10-nodes flower removal following a significant yield reduction on further deflowering in the raceme. Results revealed that rachis of the control raceme tapers from proximal to distal end. In contrast, the rachis becomes thicker at distal end of the deflowered rachis than in the distal end of control rachis. It indicates that tissues particularly vascular bundles were poorly developed in the distal end of control raceme but it was well developed at the corresponding position under deflowered condition as indicated by anatomical study. Removal of proximal flowers from 10-30 nodes, however, allowed pod development in the distal end of the raceme, which would otherwise have abscised. Such podset capacity in the distal end of the rachis was possibly due to development of adequate xylem and phloem tissues in the distal part of the deflowered rachis, like a control rachis in the proximal position. The presence of pods in the proximal end on racemes interfere the development of distal pods and increased the abscission probability of reproductive structures borne at distal position in mungbean.