Abstract
The starch content of the cotyledon and vascular bundle development during nut growth were examined in Japanese chestnut (Castanea crenata Sieb. et Zucc.). The approximately linear increase observed in the fresh weight of the cotyledon from the end of July until harvest was closely related to the increase in the starch content of the cotyledon. The starch, which accumulated from around the inside of the cell to its center, was initially detected at the beginning of cotyledon growth. The subsequent deposition of starch in ‘Tanzawa’ occurred approximately one month before it did in ‘Tsukuba’. The maximum starch content (% on dry weight basis) was observed in mid-August in ‘Tanzawa’ and in mid-September in ‘Tsukuba’. With respect to the transport and accumulation of carbohydrates in the cotyledon, the development of extensive vascular bundle connections between the seed coat and central axis during the growth of the cotyledon suggests that carbohydrate transport into the cotyledon cells could be derived from these vascular bundles. Based on the developmental stage during which starch accumulation occurs, tree management from an early period of nut growth may be important for starch accumulation in the cotyledon.
