关键词: 长江中下游稻区, 双季晚稻, 粳稻, 产量, 光能利用效率, 米质

Abstract: The middle and lower reaches of the Yangtze River is a major rice production areas with single and double rice cropping systems coexisted. With the increasing demand for the high quality rice, applying the japonica rice seems to be a promising choice in double season. In current study, the climate （temperature and solar radiation） conditions of the double season in the middle and lower reaches of the Yangtze River area were summarized. The applied varieties （indica/japonica） were introduced, furthermore, the physiological and agronomic performances （the grain yield production, the yield components, the dry-matter accumulation, the dynamics of the tiller and leaf, the growth period, the utilization rate of temperature and solar radiation, and grain quality） between the japonica rice and indica rice in the late season were compared. Generally speaking, the grain yield, grains per panicle and seed setting rate were significantly higher in the late japonica rice than that of late indica rice. The accumulation of dry matter during vegetative stage is not significant different between the japonica rice and indica rice, however, the dry matter accumulation and grain filling rate during ripening stage are greater in japonica varieties than that in indica varieties, these results indicated a greater yield potential in late season japonica varieties than indica ones. In addition, the japonica rice is more stable than indica rice in the dynamic of tiller producing, which will result in a greater photosynthetic capacity during ripening stage, and higher resource utilization, in compared with the late indica rice; a longer growth period was also found in japonica rice than in indica rice, which might result from the delayed heading and the extend grain filling stage. For climate resource, the japonica rice accumulated more temperature and sunlight hours than indica rice. Considering the higher leaf area index, greater photosynthetic capacity and shorter jointing to heading period than the late indica rice during the ripening stage, it suggested that the applying the japonica varieties in the late season might improve the temperature and solar radiation use efficiency, compared with the traditional option （indica rice）. Besides the superiors in grain yield and resource utilization, the grain quality of late japonica rice is better than that of late indica. Therefore, applying the japonica varieties instead of the indica ones in the late season might be an optimum choice in achieving the stable yield and improved grain quality in the middle and lower reaches of the Yangtze River.

Key words: the middle and lower reaches of the Yangtze River, double cropping late rice, japonica rice, yield, temperature and light use efficiency, quality