The relationship between fruit size and cell division and enlargement in cultivated and wild persimmons

To determine the anatomical basis for differences in fruit size in Japanese persimmon (Diospyros kaki Thunb.), the number and sizes of parenchymal cells were measured in four astringent cultivars and in wild D. lotus over a single season in Japan. Fruit weight at harvest correlated with the final number of parenchymal cells (r = 0.95*) and their size (r = 0.92*). There was also a correlation between fruit diameter and the number of cell layers at full bloom (r = 0.93*), which increased 1.7 - 1.9-fold during fruit development. The duration of cell division and the sizes of the cells at full bloom were similar among the cultivars, whereas mean parenchymal cell lengths increased by 7.7-,6.7-,5.4-,5.0- and 3.8-fold from full bloom to harvest in 'Otanenashi' (average fruit diameter = 96 mm), 'Hiratanenashi' (77 mm), 'Saijo' (54 mm), 'Tsurunoko' (44 mm), and D. lotus (20 mm), respectively. The final size of tannin cells was larger in 'Otanenashi' and 'Hiratanenashi' than in the other cultivars, including the wild species. These results indicate that the size of fruit at harvest was determined by the number of cells at full bloom, and their expansion during fruit development.