| 摘要: |
| 【目的】 研究3个地理种群红砂的光合蒸腾速率日进程特征，对其水分利用效率特征以及不同地理种群红砂对干旱环境的反应机制进行分析。【方法】 在自然条件下，以分布于甘肃兰州九州台（LZJ）、张掖临泽（ZYL）和武威民勤(WWM)3个地理种群的红砂(Reaumuria soongorica)为试材，利用手提式光合测定系统，于2008年在红砂生长季节(7-8月)对其气体交换的特征参数(净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）)的日变化进行了测定，并对其水分利用效率（WUE）进行计算。【结果】 3个地理种群红砂叶片Pn和Tr日变化均为双峰型，在中午13：00有光合“午休”现象。在水分条件（降雨量和土壤含水率）较低的ZYL和WWM 2个地理种群中，红砂的Pn和Tr均降低，第1峰值均提前1 h，光合“午休”时间延长，但3个地理种群红砂的Pn和Tr均较低，属于低光合、低蒸腾型。3个地理种群红砂Pn的“午休”(09：00（10：00）-13：00)主要决定因素为气孔导度，而Pn在07：00-09：00（10：00）的上升和15：00-18：00 的降低主要取决于非气孔因素。红砂水分利用效率（WUE）日变化也为双峰型，且在3个地理种群间红砂WUE的日均值随水分含量的降低而提高。【结论】 不同地理种群的红砂气体交换日变化特性虽存在一定的共性，但也有差异；水分条件是导致红砂气体交换特性产生差异的主要因素；红砂是一种通过降低蒸腾而提高水分利用效率来适应极端荒漠生境的旱生植物。 |
| 关键词: 地理种群 气体交换 水分利用效率 红砂 |
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| 基金项目:国家林业局重点科研项目(2006-35)；甘肃省科技攻关项目(2GS064-A41-003-01) |
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| Gas exchange characteristics of Reaumuria soongorica from three geographical populations |
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| Abstract: |
| 【Objective】This paper researched diurnal change characteristics of phtosynthsis and transpiration of Reaumuria soongorica from three geographical populations,and analysed their characteristics of water use efficiency(WUE) and their reaction mechanism to drought stess.【Method】 Using portable photosynthesis analysis system,the gas exchange characteristics such as the net photosynthetic rate (Pn),transpiration rate (Tr) and stomatal conductance (Gs) diurnal changes of R.soongorica from three geographical populations (LZJ,WWM,and ZYL) were studied from July to August under natural environment.【Result】 The net photosynthetic rate and transpiration rate diurnal changes of R.soongorica from LZJ,WWM and ZYL were all bimodal,and there was the phenomenon of “midday depression” at 13:00.The Pn and Tr of R.soongorica from ZYL and WWM where had lower water condition such as annual mean precipitation (AMP) and soil water content (SWC) were lower than that of LZJ,and the maximum Pn and Trof R.soongorica from ZYL and WWM presented at 09:00 that was one hour advanced than that of LZJ ,and the time of “midday depression” was prolonged,but the Pnand Tr of R.soongorica from three geographical populations were all low and their phtosynthetic types were low Pn and Tr.The phenomenon of “midday depression” (09：00 (10：00)-13：00) of R.soongorica from three geographical populations resulted from the stomatal factors,and the non stomatal factors contributed much to the rising in the morning (07：00-09：00(10：00))and the decline in the afternoon (15:00-18:00) of Pn.WUE of R.soongorica from three geographical populations were also bimodal and rose with the lowering of water condition.【Conclusion】 The diurnal changes of gas exchange characteristics of R.soongorica from three geographical populations have some generality,but also have difference.Water condition is the main factor that causes the difference.R.soongorica is the desert plant that adapts to the adverse circumstances by reducing Trand increasing WUE. |
| Key words: geographical population gas exchange water use efficiency Reaumuria soongorica |
