Abstract: By means of chemical hybridizing agents hybrid rice (Le／Qi) was obtained from cross between Lemont and Qiguizao，which are adapted to high and low light intensities respectively. Le/Qi and its parents were treated with high and low light in growth chamber for 30 days，measurements of photosynthetic characters and growth analysis were carried out every 10 days．Experimental results from quantum yield and Pn measurements indicated that the adaptable range of Le／Qi to high and low light intensities was improved，comparing with its parents. Especially under high light the relative reducing value of quantum yield of Le／Qi was much lower than that of Qiguizao．Crop growth rate (CGR) and increase rate of biomass of Le／Qi was remarkably higher than that of its male parent Qiguizao, an elite rice variety in Guangdong under both high and low light. The cause of it was that Le／Qi possessed higher LAI and NAR because of heterosis.

Key words: Chemical hybridizing agents, Crop growth rate, Hybrid rice, Photosynthetic adaptability, Photosynthetic productivity, Photosynthetic rate, Quantum yield

摘要： 用不同光强生态型水稻品种Lemont和七桂早，利用化学杂交剂配制得杂种稻Le／七。对Le／七及其亲本在人工气候箱中高、低光强条件下处理30 d，每10 d作一次光合测定及生长分析。量子产量和单叶净光合速率的测定结果表明：Le／七对高、低光强的适应范围比双亲有所扩大，尤其是在高光强下量子产量相对降低值Le／七比七桂早明显为低。处理期间杂种Le／七比七桂早明显为低。处理期间杂种Le／七的光合生产力(以作物生长率CGR表示)和生物学产量增加值在高、低光强条件下均明显超过了其父本广东当地优良品种七桂早，其CGR和生物学产量高的主要原因是其叶面积指数(LAI)、净同化率(NAR)由于杂种优势比七桂早明显为高。

关键词: 杂交稻, 光合作用, 适应性, 产量, 化学杂交剂, 作物生长率