Physiological bases of flower and pod abscission in mungbean
1989
Ahmed, Jalal Uddin
Field experiments were conducted with exogenous sucrose spray, various source-sink manipulations, and various genotypes were compared to determine physiological mechanisms that regulate the flower and pod abscission levels in mungbean. Results indicate that sucrose spray inhibited the net assimilation and crop growth rate during early reproductive stages (35-42 DAS) when the flowers and pods are still small sinks. Net assimilation and crop growth rate during later reproductive stage (45-56-DAS) due to sucrose spray along with extended sink capacity (raceme dry weight) particularly from the middle canopy nodes (nodes 4, 5, and 6). However, the abscission level of the whole canopy remained unaffected by sucrose spray. Major source removal in a morphological unit (trifoliate leaf and raceme at node 6) reduced pod dry matter yield without affecting flower and pod abscission levels. Removal of the basal leaf (below node 6) exhibited a reverse effect. The genotypes poor in cytokinin (zeatin and zeatin riboside) concentration in the reproductive tissue had higher abscission levels and allocated limited dry matter for reproductive growth. Moreover, a decline in cytokinin level with age is associated with higher abscission levels in all genotypes. Over all the experimental results indicate that carbohydrate levels in mungbean plant does not affect the flower and pod abscission level. The magnitude of flower and pod abscission varies with the cytokinin level of the reproductive tissues. It also appears that the supply of carbohydrates to the root system has some bearing on the abscission level by affecting the ability of the root to synthesize cytokinin
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