【摘要】 在自然条件下对塔里木荒漠区优势树种——胡杨、灰叶胡杨的气体交换特性及其与环境因子的关系进行研究。结果表明:(1)在6~9月生长季,胡杨和灰叶胡杨的净光合速率(Pn)、蒸腾速率(Tr,除8月)日进程均为单峰曲线,胞间CO2浓度(Ci)呈"V"字型曲线,Pn的峰值出现在12:00,Tr峰值明显滞后于Pn。生长季内胡杨各月份的Pn、水分利用率(WUE)、光能利用率(LUE)均高于灰叶胡杨,而Tr低于灰叶胡杨,气孔导度(Gs)相近。(2)气体交换与环境因子的统计分析表明,光量子通量密度(PPFD)是决定胡杨和灰叶胡杨Pn和Tr的主要环境因子,其次为气温(Tair)。(3)灰叶胡杨对PPFD、Tair、空气相对湿度(RH)的敏感性强于胡杨,通过高蒸腾耗水、低WUE来减轻高温干旱的伤害;胡杨通过主动调节Gs来控制蒸腾失水、提高光合效率,以较高的WUE和LUE适应日益干旱的荒漠环境,表现出较强的生态适应性。更多还原

【Abstract】 The gas exchange characteristics of P.euphratica and P.pruinosa of desert dominant plants and the relationships between them and environmental factors were studied under field condition.The results showed diurnal course of net photosynthetic rate (Pn) and transpiration rates (Tr) of P.euphratica and P.pruinosa’s were single peak curves from June to September except August,but intercellular CO2 concentration were double peak curves.The peak values of Pn appeared at 12:00 and peaks of Tr lagged Pn.The monthly Pn,water use efficiency (WUE),light use efficiency (LUE) of P.euphratica were higher than that of P.pruinosa in whole growth season and the stomatic conductance were similar,but Tr of P.pruinosa was higher than that of P.euphratica.The relationships between internal,external factors and Pn,Tr were analyzed by correlation,partial correlation,path and decision analysis.The results indicated that photosynthetic photon flux density (PPFD) was primary determining factor which affects Pn and Tr.The secondary factor was air temperature.P.pruinosa was more sensitive to environmental factors than P.euphratica.It reduced the hurt of high temperature and drought with high transpiration and low WUE.But P.euphratica improved photosynthetic efficiency,WUE,LUE and took the initiative to adjust stomatic conductance to decrease transpiration.It has better ecological adaptation to survive in desert environment.All above characteristics resulted to distribute in different region of P.euphratica and P.pruinosa population in course of long-period adaptation and evolution.更多还原