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刺槐光合气体交换与环境因子的关系
郑 元, 赵 忠, 周靖靖
西北农林科技大学 西部环境与生态教育部重点实验室
摘要:
【目的】研究刺槐的光合生理参数在日进程中与各环境因子的关系,筛选出影响刺槐光合气体交换的主要环境因子。【方法】采用Li-6400便携式光合作用系统,以陕西省永寿县马莲滩流域的18年生刺槐为研究对象,原位测量其冠层叶片的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO2浓度(Ci)等光合生理参数,与光合有效辐射(PAR)、水汽压亏缺(VPD)、空气温度(Ta)、空气CO2浓度(Ca)和空气相对湿度(RH)等环境因子的日进程,并计算刺槐叶片的瞬时水分利用效率(WUE)、瞬时羧化效率(CE)和气孔限制值(Ls);同时利用通径分析方法,探讨各环境因子对刺槐Pn、Tr和Gs 3种重要光合生理参数的直接影响和间接影响。【结果】刺槐Pn的日变化为单峰曲线,在10:00-14:00,刺槐Pn的降低主要由气孔限制引起;而14:00-18:00,Pn的降低由非气孔限制引起;Tr、Gs和PAR的日动态趋势与Pn相似;WUE于08:00出现全日最高峰,CE在10:00-16:00保持在较高水平;Ci于06:00达到全天最大值后逐渐下降,其日变化趋势与Ca相似,而与VPD相反;Ta早、晚低,白天高,与RH呈现相反的日变化动态。对于Pn,PAR的直接影响最大,VPD和RH的间接影响较大;对于Tr,Ta和RH的直接影响较大,RH的间接影响最大;对于Gs,RH和Ta的直接影响较大,RH的间接影响最大。【结论】在刺槐叶片进行气体交换的日进程中,环境因子对刺槐不同光合生理参数的影响程度不尽相同。总体而言,光合有效辐射、空气温度和空气相对湿度是影响刺槐光合气体交换的主要环境因子。
关键词:  刺槐  光合作用  环境因子  通径分析
DOI:
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基金项目:国家“十一五”科技支撑计划项目(2006BAD03A1207)
Relationship between photosynthetic gas exchange of black locust and environmental factors
Abstract:
【Objective】The study was done to analyze the relationship between photosynthetic physiological parameters of black locust and environmental factors in the diurnal dynamics,and to choose main environmental influencing factors to photosynthetic gas exchange of black locust.【Method】Diurnal dynamics of net photosynthetic rate (Pn),transpiration rate (Tr),stomatal conductance (Gs) and intercellular CO2 concentration (Ci) of canopy leaves of black locust (18-year-old) as well as the environmental factors photosynthetic active radiation (PAR),vapor pressure deficit (VPD),air temperature (Ta),ambient CO2 concentration (Ca) and relative humidity (RH) were measured in situ using a LI-6400 portable photosynthesis system at the Maliantan valley of Yongshou county,Shaanxi Province.Water use efficiency (WUE),carboxylation efficiency (CE) and stomatal limitation (Ls) were calculated.Both direct and indirect effects of environmental factors on important photosynthetic physiological parameters (including Pn,Tr and Gs) of black locust were analyzed using path analysis.【Result】Diurnal dynamic of Pn presents a single peak curve,the decline of Pn at 10:00-14:00 is associated with stomatal limitation,while the decline of Pn at 14:00-18:00 is associated with non stomatal limitation;diurnal dynamics of Tr,Gs and PAR are similar to that of Pn;the biggest peak of WUE occurs at 08:00,CE keeps a higher level during 10:00-16:00;Ci exhibits the maximum value at 06:00 and a decline subsequently,the diurnal variation curve of Ci is similar to that of Ca but opposite to VPD;the trend of Ta presents lower level at morning and sunset but higher level during daytime,which shows an opposite diurnal dynamics to RH.For Pn,PAR has the biggest direct effect,VPD and RH have higher indirect effects;While Tr,Ta and RH show greater direct effects,RH demonstrates the biggest indirect effect,and Gs,RH and Ta present higher direct effects,RH has the biggest indirect effect.【Conclusion】In the diurnal dynamics of gas exchange,effects of environmental factors on photosynthetic physiological parameters of black locust are different.In conclusion,PAR,Ta and RH are main environmental factors to influence photosynthetic gas exchange of black locust.
Key words:  Robinia pseudoacacia  photosynthesis  environmental factor  path analysis