A STUDY OF THE MEGAGAMETOPHYTE IN PRUNUS AVIUM AND ITS RELATION TO FRUIT SETTING

Abstract

A cytological study of the megagametophyte in Prunus avium was undertaken to determine to what extent delayed development, cytological irregularities, or degeneration might account for failure of this fruit to set commercial crops. In 1957, under high temperatures, the proportion of embryo sacs with functional egg cells decreased rapidly following anthesis. In 1958, under low temperatures, the maximum proportion of functional embryo sacs at any one time was much lower than in 1957, and the proportion of embryo sacs with functional egg cells began to decrease within 2 days of anthesis. At anthesis in both years sufficient functional embryo sacs were present to allow a commercial set of fruit. The importance of cross-pollination immediately at anthesis is emphasized. The conclusions are supported by studies of pistils hand-pollinated at intervals after anthesis.