Abstract: Hybrid rice Lemont/Qiguizao(Le/Qi) and its parents, the female one from United States of America, and the male one from South China, were studied under controlled short-term high and moderate temperature in growth chambers to compare their photosynthetic adaptability and productivity. After short-term treatment with 41℃ (3 h), which was 12℃ higher than normal atmospheric high temperature, with light intensity of 650 μmol photons/m²s in early rice in growth chamber, the Pn of all plants were remarkably decreased. Qiguizao and Lemont reduced about 80% of normal Pn, but hybrid Le/Qi only reduced by 50% of normal Pn, showing higher tolerance to the photoinhibition damage caused by suddenly raising temperature with middle high light intensity. The CGR and biomass of Le/Qi were also remakably higher than that of both Qiguizao and Lemont under both high and moderate temperatures. This study and our previous relevant studies on hybrid Le / Qi and its parents, especially to the Qiguizao, show that the utilization of photosynthetic heterosis in the cross of two different light intensity ecotypes of rice is a promising breeding approach to enhancing photosynthctic productivity and wider adaptability.

Key words: Crop growth rate, Hybrid rice, Photoinhibition, Photosynthetic productivity, Photosynthetic rate, Temperature adaptability

摘要： 在人工气候箱控温条件下比较了杂种稻Lemont／七桂早（Leｅ／七）及其亲本Lemont和七桂早对短期高温中浊处理条件下的光合适应性和光合生产力。当早稻试验植株从室外平均高温29.4℃移至箱内经41℃处理3 h后，七桂早及Lemont两个亲本的单叶净光合速率下降80%左右，而杂种稻L3／七只下降了约50%，表现了较强的抗“高温＋中等强光”所引起的光抑制伤害。Le／七的作物生长率（CGR）及总生物量，无论在早季或晚季，无论在高温或中温条件下，都比双亲明显为高。结合以前关于高低光强适应性试验结果综合分析，可以认为由于光合作用的杂种优势，Le/七在光合适应性及光合生产力方面均比亲本有了明显的提高。

关键词: 杂种优势, 光合生产力, 温度, 适应性