Translocation and Distribution of 13C-photosynthates in ^|^lsquo;Sanyo Suimitsu^|^rsquo; Peach Trees as Affected by Different Rootstocks

The objective of this study was to elucidate the effect of rootstocks on translocation and distribution of photosynthates. Translocation of photosynthates from leaves into the various parts of plant was investigated in 3-year-old ‘Sanyo Suimitsu’ peach trees on rootstocks of Nanking cherry (Prunus tomentosa) and Juseito (P. persica) grown in plastic containers which were exposed to 13CO2 at different stages of fruit development. Regardless of the time of treatments, 13C decreased in leaves and increased in fruits in both stocks with respect to time after 13CO2 was fed. When 13CO2 was fed at the stone-hardening stage, 13C translocated into the fruits was greater in the trees on Nanking cherry than in those on Juseito, and at 120h after feeding 13C content in the fruits was about two times higher in the former than in the latter. However, in the trees fed at the ripening stage there was no notable difference in 13C content in the fruits between the two stocks. It appears that the feeding time is too late in the tree on Nanking cherry, since maturation of fruits on Nanking cherry was earlier than in those on Juseito. At both stages, the distribution ratio of 13C photosynthates in small roots was higher in the trees on Nanking cherry than in those on Juseito. The relationship between translocation and distribution of photosynthates and the size of fruits and their quality, which differed by rootstock, was discussed.