Effect of nodal position on rachis morphology and yield attributes in raceme of mungbean [Vigna radiata (L.) Wilczek]

In mungbean, pod set probability differs among nodal positions within racemes, with proximal flowers set more pod than distal flowers. Experiments were conducted in 2009 and 2010 under sub-tropical condition to investigate the effect of nodal position on morphological and anatomical features of rachis and pod yield in mungbean. Results revealed that pod setting capacity, number of seeds pod(-1), pod size and seed yield were decreased from proximal to distal end of rachis in normal raceme irrespective of season and genotype. Further, early-and later-set pods had different pod growth rate and duration with the early setting pods had higher pod filling rate and increased filling duration compared to latter ones. The rachis diameter, radial length of xylem and phloem gradually and markedly decreased from proximal end to the distal end of the raceme irrespective of season and genotype due to the vascular tissues were fewer and poorly developed in the distal part compared to that of the proximal part in the rachis. The implication of inadequate phloem tissue in relation to flower shedding in the distal part of raceme is also discussed.