采用盆栽实验，研究了不同程度干旱胁迫（重度、中度、轻度、对照，分别为15％、30％、50％、70％田间最大持水量）对荒漠灌木蒙古岩黄芪幼苗光合特性、抗氧化特性和渗透调节物质的影响。结果显示，在中度和重度干旱胁迫下，除胞间 CO2浓度外，其余各光合指标均显著下降；在轻度干旱胁迫下，蒙古岩黄芪幼苗净光合速率、PSⅡ的潜在活性与对照相比上升了20．7％和5．7％。中度和重度胁迫下蒙古岩黄芪叶片的丙二醛（MDA）含量、细胞相对质膜透性、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）以及过氧化物酶（POD）活性显著高于对照，而在轻度干旱胁迫下无明显变化。叶片中游离脯氨酸含量和可溶性糖含量以及 K＋含量随干旱胁迫的加剧而显著增加；根、茎、叶中的 Na＋含量在干旱胁迫处理中均显著下降。蒙古岩黄芪在干旱胁迫下采取协同升高叶片中 SOD、CAT、POD 活性，提高脯氨酸和可溶性糖含量，同时选择性吸收 K＋的策略来减小干旱对植株所造成的伤害。实验结果可为蒙古岩黄芪适应干旱胁迫的策略提供理论依据，为其保护利用以及干旱与半干旱区的植被恢复提供参考。%A pot experiment was conducted to determine the effects of drought stress on the photosynthetic characteristics,antioxidant properties and osmotic adjustment substances of the desert shrub Hedysarum mon-golicum .The experiment used four different water treatments of 70%,50%,30% and 15% field moisture ca-pacity,representing serious (SED),moderate (MOD)and mild (MID)stresses and the control (CK),respec-tively.The photosynthetic characteristics (except intercellular CO2 concentration)under MOD and SED were significantly lower than those under CK.Compared to CK,the net photosynthetic rate and PSⅡ potential ac-tivity under MID increased 20.7% and 5.7% respectively.The malondialdehyde content,relative plasma per-meability,and the activities of superoxide dismutase,catalase and peroxidase were significantly higher under the MOD and SED treatments than CK,while there was no significant difference between MID and CK.The contents of proline,soluble sugar and K+ in leaves showed significant increase trends with the degree of drought stress.Compared to CK,Na+ contents in leaves,roots and stems showed significant decline trends.These results show that in response to stress H .mongolocum increases the activities of SOD (superoxide dis-mutase),CAT (catalase)and POD (peroxidase),increases relative plasma permeability in leaves,improves the contents of proline and soluble sugar,and enhances the selective absorption of K+ ,thereby reducing the damage of drought to the plant.Our findings provide the theoretical basis for understanding H .mongolocum adaptation to drought stress.The study also provides references for the protection and utilization of this plant and for vegetation restoration in arid and semiarid areas.
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