FRUIT RESPIRATION FOR MAINTAINING SINK STRENGTH DURING FINAL SWELL ATGROWTH STAGE-III OF PERSIMMON FRUIT

Persimmon fruit shows a rapid increase in fruit respiration with the o nset of final swell at growth stage III. To investigate the role of th is respiration rise in provoking sink strength at growth stage III of persimmon fruit, the accumulation of C-13-photoassimilate was determin ed during growth stage III comparing the control fruit and the fruit w hose calyx lobes were removed with or without sealing their scars with ''Vaseline''. Fruit respiration was not affected by calyx lobe remova l alone. By sealing the scars with ''Vaseline'' after calyx lobe remov al, however, fruit respiration was markedly inhibited. Inhibition of f ruit respiration by calyx lobe removal and sealing the scars with ''Va seline'' decreased fruit growth, but at least one week was needed to d etect a significant decline in fruit diameter. Contrarily, inhibition of fruit respiration induced an immediate reduction in C-13-photoassim ilate accumulation into the fruit which preceded the reduction in frui t diameter. The inhibition of fruit respiration seemed to reduce the s ink strength of the fruit, which in turn suppressed fruit growth. In s pite of this remarkable reduction in fruit sink strength by inhibiting fruit respiration, sugar content and/or composition in the fruit show ed no differences between treated and control fruit. We concluded that the high respiration during growth stage III in persimmon fruit is im portant for maintaining sink strength for the final swell of fruit.