Studies on Yield-Forecast in Main Crops : XI. Analysis of grain production of rice plant in Chugoku district

Process of grain production of rice plant in Chugoku district was analized using the same data as shown in the preceding report. The results obtained were as follows: Close relation was observed between the ripening of grains (the yield per 1, 000 spikelet) and the number of spikelets per unit area, but it differed by locality, namely, the relation was negative in Okayama but positive in Tottori, and in Hiroshima the relation was positive when the number of spikelets per tsubo was less than 75 thousand and negative when much more than it, and in other localities clear relation was not seen. The yield per 1000 spikelet had close relation with the 1, 000 grain weight, and the 1, 000 grain weight had been influenced by air temperature in ripening stage, and these relations were marked in late varieties and also at San-in district. In general, sequential correlations were found to exist among the following factors which contribute toward the yield of rice grown in Chugoku district: grain yield ∝ number of spikelets ∝ number of panicles ∝ number of tillers ∝ number of secondary tillers.