PARTITIONING OF PHOTOASSIMILATES IN VIROSA TOMATOES UNDER ELEVATED CO2 CONCENTRATION

The effect of CO2 enrichment on the distribution of assimilates in tom ato plants, Lycopersicon esculentum Mill. cv. 'Virosa', was studied us ing C-14-label. Plants were defoliated except for leaves 8, 9, and 10 (numbered acropetally). Depending on the experiment, truss 1 or trusse s 1 and 2 were maintained on the plant. Within a 24-h period, the labe lled leaf (leaf 10) retained high levels of C-14 in both control and C O2-enriched plants. Truss 1 was the dominant sink for both CO2 treatme nts, drawing on a considerable supply of C-14 re-exported from leaf 8 and leaf 9. The stem and root were transitory sinks and had the capaci ty to re-export C-14 at different rates during the light and dark peri ods. Pattern of photoassimilate partitioning was not affected by CO2 t reatment.