Roles of Cytokinin and Abscisic Acid in the Maturing of Strawberry Fruits

Abstract

The changes of the activity of growth inhibitors in the latter half of the development of strawberry fruits and the interaction of cytokinin and growth inhibitors on fruit development were investigated.
1. Fruits grown at day/night temperature of 30°C/25°C matured earlier than those at 20°C/17°C. The activity of growth inhibitors in the fruits increased with their maturing, and inhibitor activity in the fruits grown at high temperature appeared earlier than that at low temperature. In chromatography of inhibitors on a Sephadex column, peak of inhibitory activity in a bioassay using rice seedling was found in fractions 5 and 6 corresponding with those of authentic ABA.
2. Number of days to maturity of fruits in vitro decreased as the concentration of ABA increased in the medium. Number of days to maturity was definitely affected by the concentration of ABA independently of BA concentration when fruits were cultured on the medium with BA and ABA. Fruit maturing was suppressed and inhibitor activity in them decreased when fruits were cultured on the medium with BA.
Based on these results, following conclusion can be induced. In the latter half of the development of strawberry fruits, ABA synthesized actively owing to lowering of cytokinin activity in fruits promotes fruit maturing.