【摘要】 在非控制条件和控制条件下对大针茅的光合及水分生理生态特性进行了研究,结果表明:大针茅净光合速率(Pn)日变化表现为双峰曲线,第一个峰值出现在12:00,第二个峰值出现在16:00,出现了明显的"午休"现象.水分利用效率(WUE)变化规律与净光合速率(Pn)的变化规律一致.蒸腾速率(Tr)日变化曲线为单峰型,峰值出现在11:00时.研究大针茅在不同光合有效辐射强度及不同CO2浓度(CCO2)范围内叶片光合及水分生理生态参数的变化特征,结果表明:光合速率(Pn)与CO2浓度(CCO2)之间回归方程为Pn=-1.451+0.032CCO2-1.379×10-5 CCO22,CO2补偿点为46.27μmol·mol-1,CO2饱和点为1160.26μmol·mol-1;Pn与光合有效辐射(PAR)之间回归方程为y=-1.099+0.019x-5.461×10-6 x2,光补偿点为58.84μmol·m-2·s-1,光饱和点为1739.61μmol·m-2·s-1.更多还原

【Abstract】 Stipagrandis’ s photosynthesis and water physio-ecology were characterized under the natural or controlled condition.The results under natural condition were as follows:1)the net photosynthetic rate(Pn)of Stipagrandis was a typical diurnal curve,which had peaks at 12:00and16:00,demonstrated an obvious midday depression phenomena;2)the water use efficiency(WUE)curve had a similar pattern as Pn’s;3)the transpiration rate(Tr)curve only had one peak at 11:00.When under controlled conditions,which were different photosynthesis active radiation(PAR)intensities and different CO2concentrations(CCO2),the results were as follows:1)the regressive equation of Pnand CCO2 was Pn=-1.451+0.032CCO2-1.379×10-5 CCO22;2)the CO2 compensation point was 46.27μmol·mol-1 CO2 and the saturation point was 1160.26μmol·mol-1;3)the regression equation of Pnand PAR was y=-1.099+0.019x-5.461×10-6 x2;4)the light compensation point was 58.84μmol·m-2·s-1 and the light saturation point was 1739.61μmol·m-2·s-1.更多还原