The Growth and Ripening of Tomato Fruits at Different Levels of Endogenous Cytokinins

Abstract

In order to study the effect of endogenous cytokinins on the growth and ripening of tomato fruits, two or four fruits were grown on the second cluster, either seeded or parthenocarpic, while the foliage was left intact or reduced to one third. Parthenocarpic fruits showed retarded development, a reduced growth rate, and a very low cytokinin content at the light pink stage of ripening. With seeded fruits the reduction of foliage considerably increased the cytokinin level at that stage. The different cytokinin contents of the fruits could be ascribed to the different relative sink activities of fruits and foliage in attracting cytokinins from the roots. Ripening was progressively retarded at increasing levels of endogenous cytokinins.