Suitable Cultivation Period of Middle-season Japonica Rice in Jianghan Plain

The suitable cultivation period of japonica as middle-season rice in Jianghan Plain was studied. 6 japonica rice varieties including Huaidao No.5, Jindao 263, Yanjing No.7, Zhendao 99, Xudao No.4 and Jinjing No.1 were used. The changes of growth period, yield and quality were studied under condition of 5 different sowing dates. The results showed that growth period of six rice varietied was shorten by the delay of sowing date. The yield of each variety was less affected by sowing date. In yield components, the total grain number per panicle had no differences. Rate of seed setting increased.1000-grain weight changed little in each variety with the delay of sowing date. The quality of the tested cultivars did not change very much. Among the main reference factors of rice quality, there were no significant differences about the brown rice rate and the refined rice rate. The whole refined rice rate, chalkiness degree and amylose content was increased with the delay of sowing date.