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

Abstract

When leaves on two-year-old 'Masui Daufine' fig (Ficus carica L.) trees were exposed to 13CO2 in mid-October, analysis showed that 13C- photosynthates were stored during dormant season and remobilized in the following spring. The 13C atom % excess during dormant season was highest in small roots and was followed in descending order by fine roots, middle-sized roots, large-sized roots, trunk, two-year-old branches, and one-year-old branches. However, new shoots and roots exhibited relatively higher 13C atom % excess than did the old organs 25 days after bud burst. The new roots retained high levels of 13C atom % excess more than 45 days after budbreak, but the 13C atom % excess in the one- and two-year-old branches and large-sized roots dramatically decreased during 25 days after bud burst. Furthermore, a significant decrease in13C atom % excess levels in the trunk and middle-sized roots occurred between 25 and 45 days after budbreak; 13C atom % excess in new shoots was lower in the upper parts than in the lower parts 45 days after bursting. Thus, it seems that the growth of new shoots and roots in the spring depends mainly on carbohydrate reserves in adjacent older branches and large-sized roots for at least 25 days after bud burst. Subsequently, for the next 20 days, new growths rely on the stored food in the trunk and middle-sized roots; eventually, parts of the elongating shoot apices import photosynthates from the lower new leaves.