Studies on the Starch Contented in the Tissues of Rice Plant : III. Effects of cutting leaf-blade and thinning panicle-branch at heading time on fruiting and on the amount of starch in the culm.

Abstract

In his previous reports, the author demonstrated that for rice plants it is very desirable to maintain many green leaves at the ripening period for producing a good yield and quality of the grain, and that abundant starch is found remaining in the culms of harvested plants in such a case. In the present study, he tried further to elucidate the relation between the quality of the grain and the amount of starch in the culm. In the experiment, the leaf-blades were cut off from the plant or the panicle-branches were thinned at the heading time, for the purpose of changing artificially the relativity between assimilatory abilty and storing capacity of assimilated substances. By cutting off the all leaf-blades at the heading time, the fruiting percentage and the weight of the kernel were both lowered remarkably, and the grains harvested became very poor in quality. By thinning the panicle-branches, the effect was reverse. In the culm of the plant deprived of the leaf blades, starch diminished rapidly. and vanished completely within two weeks after the treatment, while in that the panicle branches of which were thinned, there remained abundant starch, the fact-indicating want of spaces in tue kernel tissues to receive and store the substance. Compound starch grains were seen in the pericarp tissues on the next day of flowering, they developed in size, and after two weeks they disappeared. In the endosperm tissues, compoud grains were similarly observed on the fourtn day after flowering, and then increased rapidly in volume. It was very interesting to note that the number of single grains constructing a compound starch gain was larger in the endosperm than in the vegetative tissues including the pericarp.