锡林浩特草原区27种植物净光合速率影响因素的多因子分析

Multifactor Analyses of Impacting Net Photosynthetic Rate for 27 Species in the Xillinhot Steppe

植物净光合速率的关键影响因子关系到草原生产力的波动和稳定性。实地测定锡林浩特草原22个样地27种共82株植物的光合指标和环境影响因子,采用Pearson相关性分析、多元回归分析、通径分析、决策系数分析等方法,分析各因子与草原植物净光合速率的关系。结果表明:锡林浩特草原区植物净光合速率与气孔导度、蒸腾速率呈极显著正相关,与胞间CO2浓度呈显著负相关;净光合速率与水分利用效率呈线性相关;在影响草原植物的环境因子中,净光合速率随大气相对湿度的增加而增大,而空气温度对净光合速率的影响并不显著;由通径分析可知,水分利用效率、蒸腾速率、气孔导度和大气相对湿度成为影响净光合速率的主要因素。决策系数表明,锡林浩特草原区植物的蒸腾速率、水分利用效率、气孔导度、胞间CO2浓度4个生理因子是净光合速率的主要决策变量,而环境参数中的空气温度和大气相对湿度,则成为净光合速率的限制性因素。影响草原植物净光合速率的因素有蒸腾速率、水分利用效率、气孔导度和大气相对湿度。

The key impact factors of plants＇ Pn（ net photosynthetic rate） in the typical steppe were related with the fluctuation and stability of grassland productivity. This research tested the photosynthetic indexes and their environmental factors of 82 plants,27 species in 22 sample plots. Pearson correlation analysis,multiple regression analysis,path analysis and decision coefficient were used to analyze the relationships between Pn and its impact factors. The results showed that the relationships between Pn and Gs（ stomatal conductance）,Tr（ transpiration rate）of the steppe plants were significant positive correlation in Xillinhot steppe; Pn and Ci（ intercellular CO2concentration） had a significant negative correlation; Pn and WUE（ water use efficiency） has a linear relation. Among the environmental factors which influenced the steppe plants,Pn was increased with RH（ ambient humidity）,while Ta（ air temperature） did not significantly influence Pn. Path analysis indicated that WUE,Tr,Gs and RH were major factors of impacting Pn for grasses. Decision coefficients showed that Tr,WUE,Gs and Ci promoted the decision variables of Pn,but Ta and RH were the restrictive factors for the photosynthesis of plants in the typical steppe.This research showed that Tr,WUE,Gs and RH were the main impact factors for Pn. The results in the paper could offer a basic analysis on the impact factors of grass productivity in the steppe area.