Fruit Shape of Watermelon as Affected by Placement of Pollen on Stigma

Abstract

Flowers of watermelon (Citrullus vulgaris) var. Blue Ribbon have an inferior, tricarpellary ovary with a single style and three stigmas. Flowers pollinated on 1 or 2 of the 3 stigmas give rise to fruits which are radially asymmetrical, especially at the blossom end. Differences in the median cross-sectional areas among pollinated and unpollinated carpels of these melons were significant beyond the 1% level. Seed counts of the individual carpels showed that the majority of pollen tubes grew into the carpel directly below the stigma on which the pollen grains were placed, while 21-22% grew into each of the other 2 carpels. Asymmetrical fruit development is caused by non-uniform pollen distribution.