EFFECT OF OVULAR RECEPTIVITY ON SEED SET AND FRUIT-DEVELOPMENT IN CUCUMBER (CUCUMIS-SATIVUS L)

Seed set and fruit development in cucumber (Cucumis sativus L.) were s tudied in relation to female flower receptivity from day -2 before ant hesis to day + 2 after anthesis. The female cucumber flower is protogy nous. The pistil was receptive 2 days before anthesis. The iso-electri c focusing (IEF) patterns of the stigma/style proteins, were identical from day -5 to day +2. In pollinated flowers in vivo germination and pollen-tube growth in the ovary were affected by pistil age from day - 2 to day +2. In addition, differences in sectorial filling in full see ds were observed within the fruits. A negative correlation was observe d between the frequency of fertilized ovules in the pedoncular part of the fruit and ovary length at the time of pollination. In the whole f ruit, significant differences in the number of full seeds and fruit si ze at maturity were found, and these were observed to be correlated wi th the various stages of female flower maturation at pollination. The day -2 and day +2 stages yielded the smallest fruits with few full see ds compared to the day -1, day 0 and day +1 stages, which had the bigg est fruits and a large number of full seeds. A strong positive correla tion was found between total seed number (including full and empty see ds), fruit length and weight at maturity. All these results suggest th at both seed set in the different parts of the fruit and fruit develop ment are controlled by ovular receptivity rather than by stigma/style receptivity.