桂西南岩溶区八种适生植物光合性状的变异与关联

Variation and correlation of photosynthetic traits of eightadaptive plants in karst region of Southwest Guangxi

关键词:  光合性状, 种内变异, 种间变异, 叶经济谱, 岩溶

Key words:  photosynthetic traits, intraspecific variation, interspecific variation, leaf economics spectrum, karst

摘要:

为探究岩溶植物的光合生理适应机制,采用Li-6400XT便携式光合作用测量系统,对广西平果市岩溶区8种适生植物的叶片净光合速率(P_n)、气孔导度(G_s)、胞间CO₂浓度(C_i)、蒸腾速率(T_r)、水分利用效率(WUE)和气孔限制值(L_s)等光合特征参数进行了测定分析。结果表明:(1)6个光合特征参数在种内和种间均存在不同程度的变异,并且种内变异均大于种间变异。(2)G_s和T_r的变化主要来源于种间变异(46.72% ～ 49.76%),而P_n、C_i、WUE和L_s变化主要来源于种内变异(48.66% ～ 64.50%)。在生活型水平上,P_n、G_s和T_r的种内变异表现为常绿植物小于落叶植物,而C_i、WUE和L_s则相反。(3)各参数的种间变异均表现为落叶植物大于常绿植物。(4)无论在种内还是种间,G_s的总体变异程度最大,其次是T_r和P_n,再次是L_s和WUE,C_i最小。P_n、G_s和T_r三者之间呈显著正相关(P<0.01); L_s与WUE呈显著正相关(P<0.05),而与G_s和C_i呈显著负相关(P<0.05)。这种关系与全球尺度基本一致,反映了植物对资源的权衡策略,验证了岩溶植物叶经济谱(LES)的存在。(5)常绿植物具有较高的L_s、WUE和较低的G_s、T_r、C_i及P_n,在LES中的位置更靠近具有高WUE、低蒸腾、低光合等特点的“缓慢投资-收益”型物种的一端; 而落叶植物与之相反,位于低WUE、高蒸腾、高光合等特点的“快速投资-收益”型物种的一端。该研究结果表明,植物通过性状间的协同与权衡,采取了不同的生存策略以适应变化的环境,为后续筛选适生物种,加速植被恢复演替进程提供了科学依据。

Abstract:

In order to explore the photosynthetic physiological adaptation mechanism of karst plant, the leaf photosythetic parameters of eight karst adaptable plants in Pingguo City, Guangxi were detected and analyzed, including net photosynthetic rate(P_n), stomatal conductivity(G_s), intercellular CO₂ concentration(C_i), transpiration rate(T_r), water use efficiency(WUE)and stomatal limitation value(L_s), by using Li-6400XT portable photosynthesis system. Statistical methods, such as Pearson correlation analysis, principal component analysis(PCA), and permutational multivariate analysis of variance(PERMANOVA)were also used in this study. The results were as follows:(1)Six photosynthetic parameters had different variations within and between species, and all the intraspecific variations were greater than the interspecific.(2)Change of G_s and T_r mainly originated from interspecific variation(46.72% - 49.76%), while that of P_n, C_i, WUE and L_s mainly from intraspecific variation(48.66% - 64.50%). At the life form level, the intraspecific variations of P_n, G_s and T_r of evergreen plants were less than those of deciduous plants, but the intraspecific variation of C_i, WUE and L_s of evergreen plants was higher.(3)Interspecific variations of all the parameters of deciduous plants were greater than those of evergreen plants.(4)G_s variation was the greatest both at the intraspecific and the interspecific levels, followed by T_r and P_n, then L_s and WUE, and C_i variation were the least. There were significant positive correlations among P_n, G_s and T_r(P<0.01). L_s was significantly positively correlated with WUE(P<0.05), but negatively with G_s and C_i(P<0.05). The correlations among these photosynthetic parameters are basically consistent with the global scale, which reflects the diverse trade-off strategies of plants to environment resources. The results also verified the leaf economics spectrum(LES)of karst plant.(5)Evergreen plants were located at the slow investment-return end of the LES with high values of L_s, WUE and low values of G_s, T_r, C_i and P_n. On the contrary, deciduous plants were located at the quick investment-return end of the LES with low value of WUE and high value of P_n and T_r. The results reflect karst plant adapt to changing environment with different adaptation strategies by trade-offs or co-ordinations among traits, and provide scientific basis for selecting adaptive tree species and accelerating the succession process of vegetation restoration in the karst area.