湿地植物香蒲光合特性及其影响因素分析

以湿地植物香蒲为材料,在水平潜流人工湿地处理单元中,采用便携式LI-6400光合作用测定仪测定其成熟叶片净光合速率(Pn)日变化,研究其光合生理生态特性。结果表明:香蒲叶片净光合速率(Pn)日变化呈双峰曲线,主峰(22.0μmol.m-2.s-1)出现在9:00左右,次峰(16.9μmol.m-2.s-1)出现在15:00,光合"午休"现象明显,且非气孔限制是产生光合"午休"的主要原因。用逐步多元回归方法得到净光合速率日变化与主要生理生态因子的回归方程为:yPn=0.7692+29.7059 xGs-0.7689xTr+0.014 2 xPAR(复相关系数0.9563,显著水平P=0.0001;叶片净光合速率Pn,μmol.m-2.s-1;气孔导度Gs,mol.m-2.s-1;蒸腾速率Tr,mmol.m-2.s-1;光合有效辐射PAR,μmol.m-2.s-1)。偏相关分析和通径分析的结果表明Gs、Tr和PAR与Pn的日变化显著相关,是影响香蒲Pn的主要因子,影响大小的顺序为:Gs>PAR>Tr。香蒲叶片Pn-PAR的响应曲线方程为yPn=-5×10-6 xPAR 2+0.0207 xPAR-1.3728(相关系数0.9935,显著水平p=0.000 1),光补偿点、光饱和点和表观量子效率分别为32.9μmol.m-2.s-1、147 6μmol.m-2.s-1、0.023 3 mol.mol-1;Pn-CO2的响应曲线方程为yPn=-2×10-5 w(CO2)2+0.054 9 w(CO2)-1.44 4(相关系数0.9694,显著水平p=0.000 1;w(CO2)单位为μmol.mol-1),CO2补偿点、CO2饱和点和羧化效率分别为23.7μmol.mol-1、621.4μmol.mol-1和0.0768 mol.m-2.s-1。

Photosynthetic Characteristics and its Influencing Factors of Typha angustifolia

Photosynthetic characteristics were studied by employing LI-6400 Portable Photosynthetic System to measure the diurnal variation of net photosynthetic rate(Pn) of Typha angustifolia,which grow in horizontal-subsurface constructed wetland units.The results were as follows: The curves of diurnal variation of Pn in leaves of Typha angustifolia showed two peaks,occurring at 9:00(22.0μmol.m-2.s-1) and 15:00(16.9μmol.m-2.s-1),respectively,which indicated a remarkable photosynthetic "midday depressions".The mid-depress of Pn was primarily caused by nonstomatal limitations.The regression equation of the diurnal variation of Pn and its major physi-ecological factors attained by the method of stepwise multiple-regression was as follows: yPn = 0.7692+29.7059 xGs-0.7689xTr+0.014 2 xPAR(multiple correlated coefficient R=0.9563,significance level p=0.000 1).The analysis of partial correlation and path on Pn and factors showed that the diurnal variation of Pn had significant correlation with stomatal conductance(Gs),transpiration rate(Tr)and photosynthetically active radiation(PAR),respectively.Gs,Tr and PAR were the important factors which affected Pn and the order of effecting ability was Gs > PAR > Tr.The regression equation of Pn-PAR response curveswas yPn =-5×10-6 xPAR 2+0.0207 xPAR-1.3728(correlated coefficient R=0.9935,significance level,p=0.0001),light compensation point,light saturation point and apparent quantum yield was 32.9μmol.m-2.s-1、1476μmol.m-2.s-1、0.0233 mol.mol-1,respectively.The regression equation of Pn-CO2 response curves was yPn=-2×10-5 w(CO2) 2+0.054 9 w(CO2)-1.44 4(correlated coefficient R=0.9694,significance level,p=0.0001),carbon dioxide compensation point,carbon dioxide saturation point and carboxylation efficiency was 23.7μmol.mol-1、621.4μmol.mol-1 和 0.0768 mol.m-2.s-1,respectively.