Abstract
The results obtained in the present study were summarized as follows: 1. Abscisic acid (1∼10 mg/1) accelerated the senescence of the rice leaf sections. Such effects of abscisic acid were almost reversed by high concentrations of kinetin (1∼5 mg/1); whereas low concentrations of kinetin (0.01∼0.1 mg/1) partially overcame the effect of abscisic acid. Accordingly, in the presence of abscisic acid, the level of kinetin required for chlorophyll retention instead increased. It is to be assumed that there is an antagonistic interaction between abscisic acid and kinetin. 2. It was suggested that the effect of abscisic acid in accelerating senescence was mediated through its inhibitory action on RNA synthesis which was reversed almost or partially by kinetin, since a relatively high ratio of RNA to DNA due to kinetin pretreatment was lowered according to the following transfer from kinetin to abscisic acid.
