Role of the Hull in the Ripening of Rice Plant : V. Water loss in hull and development of rice kernel

Abstract

Water loss in hull and the effect of aerial humidity on the development of kernel were investigated. The results obtained are as follows: 1. The rate of water loss in the hull after detaching from panicle decreased, as ripening proceeded in both fertile and sterile grains. 2. The rate of water loss differed among sterile, fertile grains, and hull of fertile grains, being higher in the following order: sterile grain>hull of fertile grain>fertile grain. 3. The rate of water loss was much lower in normal than in malformed grain. 4. The water loss in panicle was affected by SiO2 application and it was higher in detached panicle in plots without SiO2 application. 5. By glume top clipping, the development of the kernel was inhibited very severely. But even though the top of glume was clipped, the development of kernel was not prevented so severely under high aerial moisture conditions. And even under the same moisture conditions, when the glume-top-clipped kernel was covered with a parafilm bag, the development of the kernel was better than that without covering of parafilm bag. From these results, it was shown that in the ripening of rice plant, the hulls play an important role in keeping high moisture condition in grain, thus enabling the kernel to achieve a normal development.