灌溉量对2种灌木光合特性和水分利用效率的影响

采用野外试验，研究了灌溉量对新疆策勒绿洲木沙拐枣（Calligonum mongolicum）和花棒（Hedysarum scoparium）光合特性和水分利用效率的影响。结果表明：（1） 随着灌溉量的增加，沙拐枣和花棒的净光合速率均增加，但是蒸腾速率、气孔导度、胞间CO₂浓度没有明显增加；（2） 灌溉增加了沙拐枣的清晨水势和正午水势，并且只有灌溉和无灌溉处理的正午水势差异显著（p<0.05）；而灌溉只增加了花棒的清晨水势，并且只有充分灌溉和无灌溉的条件下差异显著（p<0.05）；（3） 在不同的灌溉条件下，沙拐枣和花棒的稳定碳同位素比率δ¹³C变化不大，沙拐枣在无灌溉、适度灌溉、充分灌溉下δ¹³C的平均值分别为-12.267、-12.147、-11.958，花棒的δ¹³C分别为-27.928、-28.068、-27.166；（4） 沙拐枣和花棒的水分利用效率均在无灌溉条件下明显高于灌溉条件下，而且一次性的灌溉不会改变其水分利用效率。

Effects of Irrigations on Photosynthetic Characteristic and Water Use Efficiency of Calligonum mongolicum and Hedysarum scoparium

Field experiment on the photosynthetic characteristic and water use efficiency of two kinds of desert shrubs was carried out under different irrigation amounts. The results showed that: (1) with increasing irrigation amounts, the photosynthetic rate of Calligonum mongolicum and Hedysarum scoparium increased, whereas the transpiration rate(Tr), stomata conductance(G_s) and intercellular CO₂ concentration(C_i) did not alter notably. (2) the irrigation increased the predawn and midday water potential of the C. mongolicum, and only the midday water potential had a notable difference under the conditions between the irrigation and no irrigation(p<0.05), while only the midday water potential of the H. scoparium increased with increasing irrigation, and the difference between the sufficient irrigation and no irrigation is only distinct(p<0.05). (3) the δ¹³C did has little change under the conditions between the different irrigation conditions, the δ¹³C average value of C. mongolicum was -12.267, -12.147 and -11.958 respectively in the no irrigation, moderate irrigation and sufficient irrigation, while the δ¹³C average value of H. scoparium was -27.928、-28.068、-27.166, respectively. (4) the water use efficiency of no irrigation of C. mongolicum and H. scoparium was obviously higher than that of the irrigation. Moreover, one time irrigation did not alter their water use efficiency.