PARTITIONING OF PHOTOASSIMILATES IN AVOCADO (PERSEA-AMERICANA MILL) DURING FLOWERING AND FRUIT-SET

To assess competition for photoassimilates among developing infloresce nces, fruitlets and vegetative shoots in avocado (Persea americana Mil l.), the distribution of recent photoassimilates was examined before a nd during flowering, fruit set, arid the transition from sink to sourc e of developing vegetative shoots. Mature leaves, located proximal to developing reproductive organs, and developing leaves, located distal to those organs, were exposed to a one-hour pulse of (CO2)-C-14. Trans location of radiolabeled assimilates was monitored over time and among organs. Overall distribution of assimilates was dependent on dry mass of tissues regardless of organ type. Flowers and fruitlets did not de monstrate greater sink strength than non-autotrophic leaves. Organs re ceiving assimilates were in phyllotactic alignment with source leaves. Photoassimilates were never limiting, although flower and fruitlet ab scission occurred during and long after this competitive period. Carbo hydrate availability was sufficient to support the growth of both deve loping fruitlets and leaves during early stages of reproductive develo pment, and it did not limit fruitlet growth or stimulate fruitlet absc ission.