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在干旱区的极端环境,植物能否适应当地的极限环境条件,最主要的是看它们能否很好地协调碳同化和水分耗散之间的关系,也就是说植物水分利用效率是其生存的关键因子之一。就生长季胡杨叶片稳定碳同位素组成(δ13 C)、胡杨叶片水分利用效率及其影响因素进行了研究。结果表明,生长季胡杨叶片δ13 C值在-28.16‰±0.23‰～-26.82‰±0.22‰间变化,平均值为-27.70‰±0.13‰。胡杨各月水分利用效率在84.81±2.23～(70.97±2.40)μmolCO2.mmol-1 H2O间变化,平均值为(75.69±1.31)μmolCO2.mmol-1 H2O;胡杨水分利用效率变化趋势是逐渐降低。最高值出现在5月,而后不断降低,7月达到最低值。造成这种变化的原因是叶片营养物亏缺导致的叶片光合速率的减小和气温升高、土壤含水量减小以及地下水埋深加深共同导致的气孔导度的变化。
In the extreme environment of arid areas, the most important thing is whether plants can adapt to the local extreme environmental conditions is whether they can well coordinate the relationship between carbon assimilation and water dissipation, that is to say, the plant’s water use efficiency is its survival One of the key factors. The stable carbon isotope composition (δ13 C), the water use efficiency of Populus euphratica and its influencing factors were studied in the growing season. The results showed that the δ13C value of Populus euphratica var. In the growing season varied from -28.16 ‰ ± 0.23 ‰ to -26.82 ‰ ± 0.22 ‰, with an average of -27.70 ‰ ± 0.13 ‰. The monthly water use efficiency of Populus euphratica varied from 84.81 ± 2.23 to (70.97 ± 2.40) μmolCO2.mmol-1 H2O with the average value of (75.69 ± 1.31) μmolCO2.mmol-1 H2O. The trend of water use efficiency of Populus euphratica decreased gradually. The highest value appeared in May and then continued to decrease, reaching its lowest value in July. The reason for this change is the change of stomatal conductance caused by the decrease of leaf photosynthetic rate and the increase of air temperature, the decrease of soil water content and the deepening of groundwater depth caused by nutrient deficiency of leaves.