科尔沁沙地复叶槭等3个阔叶树种的光合特性及其水分利用效率

Photosynthetic Characteristics and Water Use Efficiency of Three Broad-leaved Tree Species in the Horqin Sandland

在自然条件下，利用LI-6400型便携式光合作用测定系统测定了科尔沁沙地3个阔叶树种复叶槭、紫叶矮樱和紫叶稠李的光合参数，研究各树种水分利用效率特征。结果表明：复叶槭、紫叶矮樱和紫叶稠李的净光合速率日变化呈双峰型，最大峰值出现在8：00～10：00，分别为12．22、11．70和7．24μmol·m^-2·s^-1。通过比较3个树种的蒸腾速率，得出紫叶矮樱和紫叶稠李的蒸腾速率日均值较低，分别为5．10和4．95mmol·m^-2·s^-1，而复叶槭蒸腾速率日均值最高，为6．21mmol·m^-2·s^-1；对于水分利用效率而言，3个树种的日均值由高到低分别为紫叶矮樱（1．08μmol CO2mmol^-1 H2O）〉复叶槭（0．78μmol CO2mmol^-1 H2O）〉紫叶稠李（0．69μmol CO2mmol^-1 H2O），说明紫叶矮樱对干旱环境适应能力更强。最后，通过净光合速率与各影响因子的相关分析得出，3个阔叶树种净光合速率与其胞间CO2浓度相关系数最大，分别为r复叶槭=-0．954、r紫叶矮樱=-0．968和r紫叶稠李=-0．970，说明胞间CO2浓度是影响树种净光合速率最主要的影响因子。

Photosynthetic characteristics of three broad - leaved tree species in the Horqin Sandland including Acer negundo Linn. , Prunus cistena and Prunus virginiana were determined by LI -6400 portable photosynthesis system under nature condition, and water use efficiency of these species were studied. The results indicated that diurnal variations of net photosynthetic rate of the three tree species displayed a two - peak pattern with the highest value occurring during 8：00 - 10：00, and the highest values for Acer negundo Linn. , Prunus cistena and Prunus virginiana were 12.22μmol·m^-2·s^-1, 11.70μmol·m^-2·s^-1 and 7.24μmol·m^-2·s^-1 respectively. Comparatively, the daily average value of transpiration rate of Prunus cistena （5.10mmol·m^-2·s^-1 and Prunus virginiana （4.95 mmol·m^-2·s^-1 ） were lower than that of Acer negundo Linn. （6.21mmol·m^-2·s^-1 ）. For water use efficiency （WUE）, the daily averageWUE followed the order： Prnnus cistena （1.08μmol CO2mmol^-1 H2O） 〉 Acer negundo Linn. （0. 78μmol CO2mmol^-1 H2O） 〉 Prunus virginiana （0.69μmol CO2mmol^-1 H2O）, suggesting that Prnnus cistena had the strongest adaptability to arid environment than other two species. The correlation analysis among photosynthetic parameters showed that the correlation coefficients of three broad - leave tree species between net photosynthetic rate and internal CO2 concentration were the biggest, which were rAcer negundo Linn= -0. 954, rPrunus cistena= -0. 968 and rPrunus virginiana = -0. 970 respectively, which indicated that internal CO2 concentration was the most important factor affecting net photosynthetic rate of the three tree species.