Distribution of C-13 administered to a leaf of a bearing shoot of fig trees during the fruit enlargement and maturation stages at the lower nodes

Leaves at different bearing nodes on current shoots of seven-year-old 'Masu i Daufine' fig (Ficus carica L.) trees cultivated in a greenhouse were expo sed to (CO2)-C-13 during the fruit enlargement and maturation stages at low er nodes. After one week of exposure to (CO2)-C-13, the distribution of C-1 3-photosynthate in fruit-bearing shoot was investigated. The results were a s follows: 1. When the 3rd leaf was treated during fruit set and enlargement period at lower nodes, some of the C-13 photosynthates was assimilated by the treate d leaf, while a large portion went to the developing young fruit in its axi s; the remainder was partitioned to the adjacent lower stem. Similarly, whe n (CO2)-C-13 was applied to the 6th leaf, much of the C-13-photosynthates r emained in the leaf; the rest was exported to young fruits, inflorescences, leaves, and shoots at the upper and fewer nodes. When the 9th leaf was tre ated, it retained more of the C-13-photosynthates than did the immature fru it in its axis; a significant amount was retained in the adjacent upper par t of the shoot. The C-13 accumulation data revealed that the fruit in Stage I had a greater sink strength than had the developing inflorescences. 2. When the fruit on the 5th node was treated with oil one week before harv est (August 3, 1998) to induce early maturity, it showed a highly active si nk, importing C-13-photosynthates primarily from leaves on the 3rd to the 7 th nodes.