东北沙地7种植物高温时段的生理适应对策

Analysis on the Differences in the Strategy of Physiological Regulation among Psammophytes with Different Family and Genera in Natural Habit of Desert

测定我国东北松嫩沙地和呼伦贝尔沙地自然生境中不同科属7种沙生植物高温时段叶抗氧化酶活力、渗透调节物和丙二醛（MDA）含量的日变化。结果表明：1）7种沙生植物所测定指标的日均最高和最低值，叶丙二醛含量相差2～3倍；超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活力分别相差2.2，7.5，2.5倍；脯氨酸、可溶性蛋白质、可溶性糖含量分别相差35，1.0，2.0倍。2）猪毛菜和差不嘎蒿日均 MDA 含量较低，日均 SOD，POD，CAT 活力和脯氨酸、可溶性蛋白质和糖含量也较低；扁蓿豆和小叶锦鸡儿日均 MDA 含量较高，日均POD和 CAT活力、脯氨酸、可溶性蛋白含量也较高；叶细胞膜脂过氧化程度与抗氧化酶活力和渗透调节含量正相关。3）在渗透调节物种类上，豆科植物依靠脯氨酸，黄柳和冰草依靠可溶性糖；在抗氧化酶种类上，扁蓿豆、小叶锦鸡儿和冰草依靠 POD和 CAT，胡枝子和黄柳依靠 SOD。可见，东北沙地7种植物通过维持高抗氧化酶活力和渗透调节物含量抑制膜脂过氧化以适应风沙环境。

In this study,the daily changes of antioxidant enzyme activities,the contents of malondialdehyde （ MDA） and osmoregulation substances were measured in leaves of Salix gordejevii,Artemisia halodendron,Melissitus ruthenicus, Salsola collina,Agropyron cristatum,Caragana microphylla,and Lespedeza bicolor in different family and genera grown respectively in natural habitats of Hulunbuir desert and Songnen desert. The results showed 1 ） Among 7 species of psammophytes,the maximum value of average daily MDA content was higher 2 -3 times than the minimum one; the maximum value of average daily activities of superoxide dismutase （ SOD ） ,peroxidase （ POD ） ,catalase （ CAT ） was respectively higher 2 . 2 ,7 . 5 and 2 . 5 times than the minimum one; the maximum value of average daily contents of proline,soluble protein and soluble sugar was respectively 35 times,1 times and 2 times than the minimum one. 2） S. collina and A. halodendron had not only lower average daily content of MDA,but also lower average daily activities of SOD,POD,and CAT,and lower average daily contents of proline,soluble protein and soluble sugar. While,M. ruthenicus and C. microphylla had higher average daily content of MDA and activities of POD and CAT,and higher average daily contents of proline,soluble protein,indicating that the degree of membrane lipid peroxidation was positively correlated with antioxidant enzyme activity and osmoregulation substance contents. 3 ） In terms of kinds of osmotic adjustment substances,leguminous plants depended on proline,while S. gordejevii and A. cristatum depended on soluble sugar. In terms of kinds of antioxidant enzymes,M. ruthenicus,C. microphylla and A. cristatum hinged on CAT and POD; while,S. gordejevii and L. bicolor required for SOD. This study suggests that 7 species of psammophytes would keep higher activities of antioxidant enzymes and contents of osmotic adjustment substances to inhibit lipid peroxidation and maintain cell oxygen free radical metabolism balance to adapt to desert environment.