药用植物防风(Saposhnikovia divaricata)不同时期光合作用特性比较

Comparative study on photosynthesis of medicinal plant Saposhnikovia divaricata in different periods

通过对防风光合特性及光合有效辐射(PAR)、大气二氧化碳浓度(Ca)、气温(Ta)、叶温(Tl)和相对湿度(RH)等环境因子的同期观测,系统地研究了防风净光合速率(Pn)等在不同时期的日变化特征及其与环境因子之间的关系,为吉林省防风规范化种植提供理论依据。结果表明,不同时期防风净光合速率日变化均呈双峰型曲线,具有明显的光合"午休"现象。7月份防风光合速率中午降低主要由非气孔限制引起,8月份、9月份防风光合速率中午降低则主要由气孔限制引起,7月份高温低湿是限制防风Pn的主要环境因子。光合速率和蒸腾速率的不同步是引起水分利用效率变化的主要原因。光合有效辐射直接影响防风叶片的光合速率,从而影响防风有机物质的合成与转化,对防风生产力起到直接的限制作用。不同时期防风Pn与PAR呈显著正相关,不同时期防风叶片对不同环境因子的反映有所不同,环境因子中对Pn直接作用由大到小为7月份Ta>PAR>Tl>Ca>RH,8月份为Tl>PAR>Ta>RH>Ca,9月份为Ta>PAR>Tl>Ca>RH。

The diurnal changes in net photosynthetic rate （Po） of Saposhnikovia divaricata （Turcz.） Schischk. and their relationships with photosynthetic active radiation （PAR）, atmospheric CO2 concentration （Ca ）, ambient temperature （ T ）, leaf temperature （ T1 ） and relative humidity （RH） were studied systematically in different periods. This knowledge is essential for formulating generalization regarding the cultivation of the species in Jilin Province. Results showed that the diurnal changes in P of the species in different periods were similar and could be expressed as two-hump curves, reflecting a significant middy depression. The decrease in Pn during midday was mainly resulted from non-stomatal limitation in July, but stomatal limitation occurred in August and September. High temperature and low relative humidity were critical factors constraining P in July. The non - synchronous change of Pn and E were the main reason leading the variations of WUE. PAR affected Pn, synthesis and transformation of organic matter, which restricted the production for S. divaricata. There was a significantly and positively correlation between the Pn and PAR （P 〈 0.05）. The responses of S. divaricata leaves to the environmental factors were different during growing season, and the direct effects of environmental factors in three different months were of the order ： Ta 〉 PAR 〉 T1 〉 Ca 〉 RH in July, T1 〉 PAR 〉 Ta 〉 RH 〉 Ca in August, Ta 〉 PAR 〉 TL 〉 Ca 〉 RH in September.