短穗竹夏季光合特性及其影响因子

为了研究中国特有单属种植物短穗竹夏季光和特性及其影响因子,于2013年7月中旬,利用LCpro＋SD全自动光合仪,通过对短穗竹净光合速率（Pn）的测定,采用多元逐步分析法,建立了Pn与生理生态因子关系模型。结果表明：短穗竹夏季Pn日变化呈＂双峰＂曲线,具有典型的＂午休＂现象;光补偿点（LCP）和光饱和点（LSP）,分别约为40.90μmol/（m2·s）和979.77μmol/（m2·s）,表光量子效率（AQY）约为0.016;夏季影响短穗竹Pn的主要生理生态因子有：蒸腾速率（Tr）、胞间CO2浓度（Ci）、光合有效辐射（PAR）。通过研究表明,短穗竹表现出较高的LCP和较低的LSP、AQY,说明其对光的适应性较窄,弱光下光能利用率较低。

Photosynthetic Characteristics of Brachystachyum densiflorum and Its Impact Factors in Summer

In order to study photosynthetic characteristics of Chinese endemic single species Brachystachyumdensiflorum（Rendle） Keng in summer and its influential factors, LCpro ＋ SD automatic photosyntheticapparatus was used to test net photosynthesis（Pn） and multivariate step-wise analysis method was used toestablish the relationship model between Pn and physiological and ecological factors. The results showed thatdaily variation of Pnof Brachystachyum densiflorum（Rendle） Keng in summer was like a curve of＂twin peaks＂,known as typical＂noon break＂; the light complementary point（LCP） and light saturated point（LSP） were40.90 μmol/（m2·s） and 979.77 μmol/（m2·s）, respecitvely, and apparent quantum yields（AQY） was 0.016. Theinfluential physiological and ecological factors to affect Pn of Brachystachyum densiflorum（Rendle） Keng insummer mainly involve transpiration rate（Tr）, intercellular CO2 concentration（Ci） and photosynthetic activeradiation（PAR）. The research showed that Brachystachyum densiflorum（Rendle） Keng was characterized byhigher LCP and lower LSP and AQY, indicating that its light adaptability was narrow, with low light energyutilization rate under weak light.