超旱生植物红砂与珍珠光合生理生态日变化特征初探

超旱生植物红砂与珍珠长期生活在严酷的生境中，形成了独特的生物学特性和生理生态适应性。在自然条件下研究了两种超旱生植物的光合生理生态日变化特征。结果表明，红砂和珍珠光合作用受环境变化影响明显，具有一定的可塑性:①在土壤含水量（SWC）、光、温、湿等条件较好的8月22日，两植物净光合速率（Pn）、蒸腾速率(Tr)日变化呈不明显双峰型。Pn红砂高于珍珠，日平均分别为(7.74±0.79)μmol5m-25s-1 和(5.64±0.75)μmol5m-25s-1；Tr也是红砂高于珍珠，日平均分别为(24.38±3.07)mmol5m-25s-1和(15.41±2.01)mmol5m-25s-1；水分利用效率（WUE）则相反，日平均珍珠大于红砂，分别为0.35 μmol·mmol-1和0.31 μmol·mmol-1。②在SWC、光、温、湿等条件较差的9月28日两植物Pn、Tr日变化呈单峰型，且值明显小于8月22日，而WUE则高于8月22日。通过对两种超旱生植物小枝水势、叶片气孔导度及叶绿素荧光参数生理特性变化的分析，得出两植物光合作用受到气孔和非气孔等多种环境及自身因子的影响。

Preliminary Studies on Diurnal Variances of Physio-ecological Characteristics of Photosynthesis of Two Extreme Xerophytes--Reaumuria soongorica and Salsola passerina

Having long lived in rigor habitats, two extreme xerophytes Reaumuria soongorica(RS) and Salsola passerina(SP) formed special biological features and physio-ecological adaptations. The physio-ecological characteristics of photosynthesis of the two extreme xerophytes were studied under natural environment. The results indicated that there was physio-ecological plasticity in the photosynthesis of the two extreme xerophytes to a certain extent: (1) On August 22 when the environmental factors were more favorable for photosynthesis, the curve of diurnal variations of net photosynthesis rate (Pn) and transpiration rate (Tr) were dual-peaked (but not obviously) and Pn of RS was lower than that of SP. Pn on diurnal average value of RS and SP were (7.74±1.06) μmol·m-2·s-1 and (5.56±1.71) μmol·m-2·s-1 respectively. Tr of RS was also lower than that of SP, Tr on diurnal average value of RS was (24.38±6.2) mmol·m-2·s-1 and (15.41±2) mmol·m-2·s-1 in SP. Water use efficiency(WUE) was different from Pn and Tr, WUE on diurnal average value of SP(0.34 μmol·mmol-1) was higher than that of RS(0.31 μmol·mmol-1) of RS. (2) But on September 28 when the environmental factors were less favorable for photosynthesis, the curve of diurnal variations of Pn and Tr changed to be single-peaked and their values were significantly reduced. The values of WUE on September 28 were higher than those of August 22. Through analysis on the variances of the physiological characteristics of small branches water potential, stomatal conductance and chlorophyll fluorescence parameters in leaves of two xerophytes, it was known that the photosynthesis in leaves was influenced by not only the stomatal factors but by the non-stomatal factors.