Parthenocarpic Fruit Set and Endogenous Indole-3-acetic Acid Content in Ovary of Cucumis sativus L.

Abstract

A study was carried out on flowers forming at nodes 6 and 30 and flowering between June and Aug. in cucumber cultivars Chojitsu-Ochiai 2 (strongly parthenocarpic) and PMR142 (weakly parthenocarpic). Female flowers were bagged the day before anthesis to prevent pollination and the ovaries measured daily until the fruits were harvested. Ovaries reaching 6 cm could be predicted to set parthenocarpically. In Chojitsu-Ochiai 2 this could occur 3 days after anthesis. In PMR142, the number of ovaries which set parthenocarpically was higher for flowers at higher nodes and with longer ovaries than for flowers at lower nodes and with shorter ovaries. The IAA content of ovaries predicted to set parthenocarpically was 3.5 times greater than that of those which did not. In Chojitsu-Ochiai 2, those ovaries which reached 6 cm in length 3 days after anthesis had 1.7 times more IAA than shorter ones, indicating a positive relationship between IAA levels and parthenocarpic fruit set.