胡杨雌雄株冠层光合速率日变化差异及主要影响因子

The Diurnal Variation of Photosynthetic Rate in Male and Female Canopy of Populus euphratica Oliv. and Its Main Influencing Factors

摘要: 以胡杨为试材，使用Li-6400便携式光合作用仪，测定了不同冠层高度下胡杨雌雄株光合参数的日变化，应用相关分析、回归分析，研究净光合速率与生理、环境因子间的关系，为植物生长调控提供理论依据。结果表明：① 胡杨雌雄株、蒸腾速率Tr与气孔限制值Ls的变化趋势均为单峰曲线，胞间二氧化碳浓度C_i日变化呈现“V”字型，水分利用效率WUE呈现上下波动趋势，胡杨雌雄株气孔导度G_s因不同冠层而表现出“单峰”型和“双峰”型两种趋势，净光合速率P_n日变化与G_s同步，峰值均出现在11:30，而T_r峰值滞后P_n、G_s2h。② 胡杨雌雄株的P_n、G_s、C_i、T_r均随着冠层的升高而增加，WUE、L_s均随着冠层的升高而减少，在11:30和15:30，胡杨雌雄冠层2 m与10 m的G_s、WUE、T_r、L_s有显著差异。③ 胡杨雌雄株对各生理因子和环境因子的响应有所不同，胡杨雌株叶片的光合作用受生理因子和生态因子的影响比雄株更显著。④ 对胡杨雌株Pn的促进作用最大的是光合有效辐射PAR，对胡杨雄株P_n的促进作用最大的是空气温度T_air；对胡杨雌雄株T_r促进作用最大的均是T_air；对胡杨雌株C_i的抑制作用最大的是PAR，对胡杨雄株C_i的抑制作用最大的是T_air；对胡杨雌株G_s的促进作用最大的是T_air，3个环境因子均对胡杨雄株G_s无显著影响。PAR是影响胡杨雌株叶片净光合速率最主要的环境因子；T_air是影响胡杨雄株叶片净光合速率最主要的环境因子。

Abstract: Taking Populus euphratica Oliv. as the test material, the Li-6400 portable photosynthesis instrument was used to measure the diurnal changes of photosynthetic parameters of male and female Populus euphratica plants under different canopy heights. Correlation analysis and regression analysis were used to study the relationship between net photosynthetic rate and physiological and environmental factors. In order to provide theoretical basis for plant growth regulation, the results showed that: ① The change trends of P_n, T_r and L_s of male and female plants of Populus euphratica were all unimodal curves, the daily variation of C_i showed a “V” shape, and WUE showed a trend of up and down fluctuations. G_s showed two trends of “single-peak” and “double-peak” due to different canopy heights. The diurnal variation of P_n was synchronized with G_s, and both peaks appear at 11:30, while the peak of T_r lags behind P_n and G_s for 2 h. ② P_n, G_s, C_i, and T_r of male and female Populus euphratica all increased with the increase of the canopy heights, while WUE and L_s decreased with the increase of the canopy heights. At 11:30 and 15:30, there were significant differences in G_s, WUE, T_r and Ls between male and female canopies of 2 m and 10 m in Populus euphratica. ③ The responses of male and female plants of Populus euphratica to various physiological and environmental factors were different. The photosynthesis of leaves of female Populus euphratica plants was more significantly affected by physiological and environmental factors than that of male plants. ④ PAR was the most promoting effect on P_n in female Populus euphratica, and T_air was the most promoting effect on P_n in male Populus euphratica; T_air was the most promoting effect on Tr in both male and female plants; PAR was the most inhibitory effect on C_i of female Populus euphratica, and T_air was the most inhibitory effect on C_i of male Populus euphratica; T_air has the greatest promoting effect on G_s in female Populus euphratica. All three environmental factors have no significant effect on G_s in male Populus euphratica. PAR was the most important environmental factor affecting the net photosynthetic rate of female leaves of Populus euphratica; T_air was the most important environmental factor affecting the net photosynthetic rate of male leaves of Populus euphratica.