Relations between the Number of Spikelets and the Percentage of Ripened Grains in Early Transplanted Rice

Four series of experiments were conducted by; (1) removing the rachis branches of "early transplanted rice" just after heading in order to equalize the number of spikelets per unit area with that of "usual transplanted rice"; (2) equalizing the number of panicles and spikelets by removing all tillers and primary rachis branches; (3) removing the upper or middle or lower rachis branch; (4) changing the amount of fertilizer and hills per area in "early" and "usual transplanted rice". In the experiment-(4), correlation between the percentage of ripened grains and the number of spikelets per area was higher than that between the percentage of ripened grains and the number of panicles per area or the number of panicles per hill or the number of spikelets per panicle. Comparing the corresponded treatments each other, "early transplanted rice" had more spikelets per area than "usual transplanted rice", but the percentage of ripened grains of the former was superior to that of the latter. Especially in the case of the similar spikelets in number, the former showed higher percentage than the latter. In the experiments-(1)·(2), the percentage of ripened grains in "early transplanted rice" was superior to that of "usual transplanted rice". Therefore naturally we consider that ripened grains of "early transplanted rice" show higher percentage than that of "usual transplanted rice", but usually "early transplanted rice" have more spikelets, so the percentage of ripened grains in the former was not always superior to that in the latter.