欧李叶片秋季光合作用日变化研究

利用Li-6400便携式光合作用测定系统测定了2a生欧李叶片秋季光合生理生态特性及环境因子日变化,并采用相关分析和逐步回归法探讨了欧李叶片净光合速率的主要影响因子。结果表明:欧李净光合速率(Pn)日变化曲线为双峰型,第1峰(峰值为7.96μmol.m-2.s-1)出现在10:00左右,第2峰(峰值为6.26μmol.m-2.s-1)出现于15:00左右,具有一定程度的光合"午休"现象。欧李Pn与气孔导度(Gs)、蒸腾速率(Tr)以及光合有效辐射(PAR)显著正相关,而与胞间CO2浓度(Ci)及空气相对湿度(RH)显著负相关。其光合"午休"现象原因主要为气孔关闭引起的气孔限制因素。Gs与Ci为影响欧李Pn的关键因子,Gs影响最大、Ci次之。

Study on Photosynthetic Diurnal Variation in Leaves of Cerasus humilis (Bunge) Sok.in Autumn

The eco-physiological photosynthetic characteristics of Cerasus humilis(Bunge) Sok.leaves in two-year-old seedlings and the environmental factors were measured using Li-6400 portable photosynthesis system in the fall,also the main impact factors of the leaf net photosynthetic rate were investigated by using correlation analysis and stepwise regression analysis.The results showed that diurnal change of net photosynthetic rate(Pn) of C.humilis presented a bimodal pattern,the first peak(Pn=7.96 μmol·m-2·s-1) appeared at 10 o’clock and the second peak(Pn=6.26 μmol·m-2·s-1) appeared at 15 o’clock,and in midday there was a certain degree of photosynthetic depression.The diurnal variations of Pn related significant positively to that of stomatal conductance(Gs),leaf transpiration(Tr) and photosynthetically active radiation(PAR),but related significant negatively to that of intercellular carbon dioxide concentration(Ci) and air relative humidity(RH).The main reasons of midday photosynthetic depression was stomatal limitation factors reduced by stomatal closure.Gs and Ci were the key factors exerting an influence on Pn of C.humilis,and Gs produced more influence than Ci.