Abstract
The authors investigated the growth, grain yield and its constitutional factors in rice plants by early season culture. The results were as follows : 1) By early culture, the number of stalks and panicles, the amount of accumulated starch in the base of shoot, the weight percentage of dry matter were all increased. The grain yield was increased also according to the increase in spikelet number. However, ripening was retarded and 1, 000-grain weight decreased to some extent when the spikelet number became very large. 2) On well-drained paddy fields there were shown only little effects of early planting as above mentioned, while on ill-drained fields they were remarkable, especially when the soil was either boggy, clayey, volcanic ashy half-boggy or sandy.
