木荷光合特性日变化及其与环境因子相关性分析

运用LCA4型便携式全自动光合测定系统,在自然条件下,于9月上旬的晴天里对空旷地生境中木荷叶片光合作用日进程进行测定,结果表明木荷冠层叶片的净光合速率日进程曲线为双峰型,在午间出现明显的“午休”现象。用逐步多元回归方法得到净光合速率日变化的最优化方程为Y=-5.0105+0.0052X1+0.3869X3-0.3576X4(复相关系数R=0.9558,F值=24.6384,显著水平p=0.0004,剩余标准差S=0.7893)。偏相关分析和通径分析表明,光合有效辐射、空气相对湿度和气温与净光合速率的日变化有着极显著或显著的相关关系,是影响光合速率主要的环境因子,影响大小的顺序为光合有效辐射>空气相对湿度>气温。

Diurnal photosynthetic characteristics of Schima superba and its correlation with environment

The diurnal variation of photosynthesis of Schima superba in gap condition was studied by the LCA4 Portable Photosynthesis System under natural conditions. The results were as follows:The curve of net photosynthetic rate(Pn)in sun leaves had two peaks,which had an obvious decline of photosynthetic efficiency at noon,in fine days at early September. The mid-depress of Pn was primarily caused by nonstomatal limitations. The optimization equation of the diurnal variation of Pn was attained by the method of stepwise multiple-regression as follows:Y=-5.010 5 0.005 2X_1 0.386 9X_3-0.357 6X_4(R=0.955 8,F=24.638 4,p=0.000 4,S=0.789 3). The analysis of partial correlation and path on Pn and factors showed that the diurnal variation of Pn had significant correlation with photosynthetic effective radiation(Ql)and air relative humidity(RH),respectively. Ql,RH and Ta were the important factors which affected Pn and the order of effecting ability was Ql>RH>Ta.