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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-1H2O)>复叶槭(0.78μmol CO2mmol-1H2O)>紫叶稠李(0.69μmol CO2mmol-1H2O),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。
Under natural conditions, photosynthetic parameters of three broad-leaved species, Acer palmatum, Prunus avium and Prunus davidiana, were determined by LI-6400 portable photosynthesis system and the characteristics of water use efficiency of each species were studied. The results showed that the diurnal variation of net photosynthetic rate of Acer davidii, Prunus avium and Prunus divaricata showed a bimodal pattern with the maximum peak at 8: 00-10: 00, which was 12.22, 11.70 and 7.24 μmol.m- 2.s-1. By comparing the transpiration rate of the three species, the average daily transpiration rate of V. przewalskii and P. purpurea was 5.10 and 4.95 mmol.m-2.s-1, respectively, The highest average value was 6.21 mmol.m-2.s-1. For the water use efficiency, the average values of the three tree species from high to low were 1.08 μmol CO2 mmol-1H2O> 0.78μmol CO2mmol-1H2O)> Prunus densiflora (0.69μmol CO2mmol-1H2O), indicating that Erianthus cinnabarinus is more adaptive to arid environment. Finally, through the correlation analysis between net photosynthetic rate and various influencing factors, the correlation coefficients of net photosynthetic rate and intercellular CO2 concentration of the three broad-leaved species were the largest, r = 0.954, r = And r Purple leaf thick Li = -0.970, indicating that the intercellular CO2 concentration is the net impact of net photosynthetic rate of the most important factor.