沙坡头地区3种沙生植物水分及光能利用效率特征比较分析

Water and light use efficiency of 3 psammophytes in Shapotou Area

为了探究沙生植物对水分的响应机制和对水分、光能利用效率,以沙坡头地区3种常见的典型沙生植物柠条(Caragana korshinskii)、油蒿(Artemisia ordosica)、沙木蓼(Atraphaxis bracteata)为研究对象,用Li-6400便携式光合测定仪测定3种植物的净光合速率(Pn)和蒸腾速率(E),并分析各自的水分利用效率(WUE)和光能利用效率(LUE).结果表明,3种沙生植物的Pn日变化曲线都是双峰型,有明显的光合午休现象.E日变化曲线,柠条呈单峰型,油蒿和沙木蓼呈双峰型.柠条和油蒿的WUE日变化曲线均为双峰型,而沙木蓼的WUE日变化比较平缓.LUE日变化曲线,柠条和油蒿都是倒抛物线型,早晨和傍晚较高,而沙木蓼的LUE曲线呈平缓型.说明沙木蓼和柠条、油蒿的生存策略不同,沙木蓼是高耗水植物,依靠强烈的蒸腾作用避免高温的伤害,使得光合作用保持较高水平.因此,柠条和油蒿比沙木蓼更能适应沙区的干旱环境,是恢复植被、防风固沙的优良物种.

In order to explore the sand plant＇response mechanism to water and the utilization rate of water and light,3kinds of typical psammophyte,Caragana korshinskii,Artemisia ordosica,Atraphaxis bracteata,in Shapotou area in Tengger Desert were chosen as the research object,measured their net photosynthetic rate（Pn）and transpiration rate（E）with Li-6400 portable photosynthesis system,and analyzed their water use efficiency（WUE）and light use efficiency（LUE）.The results indicated that the diurnal variation of Pncurves of 3species of plants were two-peak pattern,had obvious midday depression of photosynthesis,the peaks occurred at 9∶00and 17∶00,trough at 13∶00,Pndaily average,A.bracteata（13.54μmol/（m^2·s）was about 2.5times as C.korshinskii（5.43μmol/（m^2·s）and 2.3times as A.ordosica（5.85μmol/（m^2·s）.Curve of E diurnal variation of transpiration rate of C.korshinskii,was single peak pattern,A.ordosica and A.bracteata were two-peak pattern,the daily average E A.bracteata was about2 times as C.korshinskii（3.34mmol/（m2·s^-）and A.ordosica（3.61mmol/（m^2·s）.The WUEcurve of diurnal variation of C.korshinskii and A.ordosica were two-peak pattern,reached peaks at 9∶00（3.21mmol/mol,∶A.ordosica∶2.95mmol/mol）and 17∶00,trough at 13∶00;and the WUE curve of diurnal variation of sand was made smooth type.The curve of diurnal variation of LUE,∶C.korshinskii∶and∶A.ordosica∶was inverted parabolic,level in the morning and evening was higher and the trough occurs at 13∶00.The highest value of C.korshinskii（0.0437mol/mol）was 10 times higher than the lowest level at noon and of A.ordosica（0.028 2mol/mol）was 5times higher than the lowest level at noon.The LUEcurve of A.bracteata was smooth,the daily average value reached 0.0226 mol/mol.The survival strategies of A.bracteataand C.korshinskii,A.ordosica were of great difference,relying on strong transpiration to avoid heat damage,the photosynthesis of A.bracteataremained at a high level,so as to improve the utilization efficiency of light.Therefore,C.korshinskii,and A.ordosicacould adapt to the drought environment of sandy area more than A.bracteata,as the excellent species of vegetation restoration,windbreak and sand fixation.