Abstract: Based on the experiment of diurnal photosynthetic variation and light response curve of 1-year Lespedeza tomentosa(Thunb.)Sieb.ex Maxim in summer,we analyzed the correlation between physiological and environmental factors which influence the photosynthesis significantly.The mean diurnal photosynthetic rate was 4.86 μmol CO₂·m^-2·s^-1 and the light compensation points was 57.61 μmol·m^-2·s^-1.The photosynthetic rate had related coefficient of 0.431,0.534 and 0.487 between photosynthetic active radiation,stomatal conductance and relative air humidity respectively,there was obviously statistically difference(P<0.01).It had related coefficient of 0.104,0.242 and 0.182 between leaf surface temperature,transpiration rate and atmosphere carbon dioxide concentration respectively,which showed the significant level(P<0.05).It had evident negative relationship betwee intercellular carbon dioxide concentration with the related coefficient of-0.61.The results showed that diurnal net photosynthetic rate variation appears double-peak curve in the summer and there be "noon break".phenomenon in Lespedeza tomentosa(Thunb.)Sieb.ex Maxim

Key words: Lespedeza tomentosa photosynthesis, diurnal variation, influencing factor

摘要： 于2009年7月以一年生绒毛胡枝子(Lespedeza tomentosa(Thunb.) Sieb. ex Maxim)为试材,利用英国生产的Lcpro⁺型便携式全自动光合测定系统对其光合作用日变化、光响应曲线进行测试,并对影响其光合作用的生理因子和环境因子进行相关性分析。结果表明:绒毛胡枝子净光合速率的日变化在夏季表现为双峰曲线,有光合"午休"现象,日平均光合速率为4.86μmol CO₂·m^-2·s^-1。绒毛胡枝子的LCP约为57.61μmol·m^-2·s^-1,LSP约为1353.39μmol·m^-2·s^-1,显示出阳生植物特性,对环境适应能力强,适合在较大范围栽植。绒毛胡枝子光合速率与光合有效辐射、气孔导度以及空气相对湿度相关系数分别为0.431、0.534和0.487,达到极显著水平(P<0.01);与叶表面温度、蒸腾速率和大气二氧化碳浓度相关系数分别为0.104、0.242和0.182,达显著水平(P<0.05);与胞间二氧化碳浓度相关系数为-0.61,有极显著的负相关关系(P<0.01);与大气温度未有显著相关性(P<0.05)。

关键词: 绒毛胡枝子, 光合作用, 日变化, 影响因子