Abstract:The effects of sowing date and seedling age on the yield and quality of two-season late japonica rice were studied using Ejing 403 as material under the combination of 2 sowing dates (June 25 and July 2) and 4 seedling ages (15,20,25 and 30 d). A field experiment with randomized complete block (RCB) design was conducted. The relationships between the temperature at the stage of grain filling and the quality of the two-season late japonica rice were analyzed to establish the high-yield and high-quality cultivation techniques for late japonica rice and to promote the development of “early indica-late japonica” plantation pattern in Hubei Province. The results showed that the heading time of the two-season late japonica rice was delayed,and the period of grain filling and the whole growth were prolonged with the delay of the sowing date and the extension of the seedling age. But the period of vegetative growth in the field was shortened. The economic yield increased first and then decreased with the prolonged seedling age when sown on June 25,a local regular sowing date for the two-season late japonica rice. The highest yield was reached at 20 days of seedling age,and long seedling ages led to the significant loss of yield. Delayed sowing resulted in a significantly low yield compared with the regular sowing time,but there was no significant difference in yield among different seedling ages under the delayed sowing date. Both delayed sowing date and prolonged seedling age made the grinding quality lower but improved the appearance quality of two-season late japonica rice. The pasting temperature of rice flour did not change much under different sowing dates and seedling ages. However,the peak viscosity and breakdown values of rice flour at the same sowing date,as well as the final viscosity at the regular sowing date,increased first and then decreased with the prolonged seedling ages,with the highest value at 20 days of seedling age. Delayed sowing date resulted in consistent decrease of peak and final viscosities and the breakdown value,which made the cooking and eating qualities of rice lower. Therefore,a high integrated rice quality can be obtained when the two-season late japonica rice is sown during the regular sowing period and transplanted with 20 days of seedling age in this region. The low temperature during the stage of grain filling may become a limiting factor for the formation of grinding and cooking and eating qualities for the two-season late japonica rice when its heading is late.