关键词：
刚毛柽柳;光合作用;蒸腾作用;水分利用效率;地下水位;塔里木河
摘 要：
【目的】研究不同地下水位条件下和不同季节塔河下游刚毛柽柳净光合速率、蒸腾速率和水分利用效率的日变化规律和特点,为阐明荒漠植物抗逆途径的多样性提供理论依据。【方法】利用LI-6400便携式光合作用测定系统,于8月初测定塔河下游三个不同地下水位样点刚毛柽柳(Tamarix hispida Willd.)净光合速率(Pn)、蒸腾速率(E)和水分利用效率(WUE)的日变化及同一地下水位条件下6、8、10月初不同季节各指标的日变化,比较分析测定指标的变化规律和指标间的关系。【结果】随着地下水位的下降,各样点刚毛柽柳的净光合速率日平均值呈下降趋势,地下水位分别为6.03、6.68和8.0 m的A、B、C样点Pn日平均值分别为12.85、9.43和9.71 mol/(mg·s),且A、B两样点的Pn值在上午时段远大于下午时段,C样点上午时段Pn值明显下降,下午时段与A、B两样点相近;蒸腾速率日均值也随地下水位的下降呈下降趋势,而水分利用率日均值呈上升趋势,A、B、C三样点的E日均值分别为6.61、5.02和3.54 mmol/(mg·s),WUE日平均值分别为1.72、1.66和2.42 mmol CO2/mol H2O,在地下水位最低的C样点WUE比水分条件较好的A样点提高了28.9%。在水分状况较好的同一水位条件A样点,8月初刚毛柽柳Pn日均值可达12.85 mol/(mg·s),而6月初和10月初分别要比8月初降低了24.3%和131.1%;E的日均值也8月初最大,分别比6、10月初高出227.5%和251.1%;WUE日均值则是6月初最高,8月初最低。【结论】塔河下游刚毛柽柳在地下水位下降为近7~8.0 m的干旱环境下,通过降低蒸腾速率,保持着体内较好的含水量,从而保证全天能维持着一定的光合水平,使得水分利用率得到有效提高,以此适应荒漠环境。在水分条件较好的情况下,为适应8月初的高温环境,刚毛柽柳通过高蒸腾降低体温,保持着最高的净光合速率日均值,但水分利用率日均值低于6月初和10月初。
译 名：
Study on Characteristics in Photosynthesis,Transpiration and Water Use Efficiency of Tamarix hispida Willd. in the Lower Reaches of the Tarim River
作 者：
WANG Yan-ling;LIU Jun;LI Wen-bing;LI Fang;College of Forestry & Horticulture,Xinjiang Agricultural University;
关键词：
Tamarix hispida;;photosynthesis;;transpiration;;water use efficiency;;groundwater level;;Tarim River
摘 要：
【Objective】In order to provide a theoretical basis for clarifying the diversity of desert plant defense pathway,this project aims to explore the daily and season changes in net photosynthetic rate,transpiration rate and water use efficiency of Tamarix hispida under different water conditions in the lower reaches of the Tarim River. 【Method】An open gas exchange system,LI- 6400 Portable Photosynthesis System was used tostudy the daily changes in net photosynthetic rate( Pn),transpiration rate( E) and water use efficiency(WUE) of Tamarix hispida under three different water conditions in early August and under the same water conditions in early June,August and October in the lower reaches of the Tarim River. 【Result】The daily average value of net photosynthetic rate of Tamarix hispida tended to be decreased with the decline in the groundwater level. The water table of A,B and C samples were 6. 03 m,6. 68 m and 8. 0 m,and the Pn on daily average value was 12. 85 μmol /( m· s),9. 43 μmol /( m·s) and 9. 71 μmol /( m·s) respectively. The Pn value of A and B samples in the morning period was greater than that in the afternoon period,and the Pn value of C sample significantly decreased in the morning period. All samples suggested that the daily average value of transpiration rate also tended to decrease with decline in groundwater level. The WUE did not decline with the decline in groundwater levels. In the driest C sample point,the WUE was 28. 9% higher than that of the sample A. From the season perspective,the Pn on daily average value of Tamarix hispida in sample A showed the highest in early August,followed by early June,then lowest in early October. The daily average value of transpiration rate was much higher in early August than that in early June and October,while WUE is the lowest in early August and the highest in early June. 【Conclusion】When the groundwater level dropped to nearly 7 to8. 0 m,Tamarix hispida in the lower reaches of the Tarim River still maintained a certain level of photosynthesis during the daytime. The study showed that Tamarix hispida in an arid environment could improve water use efficiency by reducing transpiration rate and maintain a relatively high photosynthetic rate to adapt the desert environment.
