Storage and translocation of C-13-photosynthates from 'Masui daufine' fig (Ficus carica L.) leaves administered (CO2)-C-13 in autumn

When leaves on two-year-old 'Masui Daufine' fig (Ficus carica L.) trees wer e exposed to (CO2)-C-13 in mid-October, analysis showed that C-13- photosyn thates were stored during dormant season and remobilized in the following s pring. The C-13 atom Sro excess during dormant season was highest in small roots and was followed in descending order by fine roots, middle-sized root s, large-sized roots, trunk, two-year-old branches, and one-year-old branch es. However, new shoots and roots exhibited relatively higher C-13 atom % e xcess than did the old organs 25 days after bud burst. The new roots retain ed high levels of C-13 atom % excess more than 45 days after budbreak, but the C-13 atom % excess in the one- and two-year-old branches and large-size d roots dramatically decreased during 25 days after bud burst. Furthermore, a significant decrease in C-13 atom % excess levels in the trunk and middl e- sized roots occurred between 25 and 45 days after budbreak; C-13 atom % excess in new shoots was lower in the upper parts than in the lower parts 4 5 days after bursting. Thus, it seems that the growth of new shoots and roo ts in the spring depends mainly on carbohydrate reserves in adjacent older branches and large- sized roots for at least 25 days after bud burst. Subse quently, for the next 20 days, new growths rely on the stored food in the t runk and middle- sized roots; eventually, parts of the elongating shoot api ces import photosynthates from the lower new leaves.