野生早熟禾(PoaL．)对模拟干旱的生理响应

Physiological Responses of Seven Wild Poa species to Simulative Drought Stress

以采集于甘肃境内的7种野生早熟禾(Poa L.)为材料,采用盆栽模拟自然干旱条件,研究了叶片游离脯氨酸(F-pro)、可溶性糖(SS)、可溶性蛋白(SP)和丙二醛(MDA)含量及过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性对干旱胁迫的生理响应,分析了生理指标及采集地年均降水量与抗旱性的关系,以期为早熟禾抗旱品种的选育提供依据。结果表明:随干旱胁迫时间的延长,叶片F-pro、SS和MDA含量逐渐增加,CAT活性和SP含量逐渐减少,SOD活性呈先增强后减弱的趋势。MDA含量与抗旱综合评价值极显著负相关(p<0.01),CAT活性与抗旱综合评价值显著正相关(p<0.05),二者可作为野生早熟禾抗旱性评价的主要指标。材料采集地的年均降水量与抗旱综合评价值负相关,但相关性不显著(p>0.05)。采用标准差系数赋予权重法对抗旱性进行综合评价,可将7个材料分为3类:第1类抗旱,为草地早熟禾(Poa pratensis);第2类中等抗旱,包括长稃早熟禾(Poa dolichachyra)、细叶早熟禾(Poa anqustifolia)、冷地早熟禾(Poa crymophila)和波伐早熟禾(Poa poophaqorum);第3类抗旱性弱,包括垂枝早熟禾(Poa declinata)和小药早熟禾(Poa micrandra)。

In this study, seven species of Wild Poa in Gansu province were selected to measure the physio logical responsive indices of malondialdehyde （MDA）, soluble protein （SP）, catalase （CAT）, superoxide dismutase （SOD）, free proline and soluble sugar （SS） under simulated drought stress. Further, the rela tionship between drought resistance and physiological indicators, mean annual precipitation of source and was evaluated. The results showed that the contents of free proline, SS and MDA in leaves increased gradu- ally with increasing drought stress, the CAT and SP showed a decreasing trend with increasing drought stress, while the SOD activity increased a little and then decreased slowly. The comprehensive evaluation values were negatively correlated to the contents of MDA （p 〈0.01）, but positively correlated to CAT. This implied that the contents of MDA and CAT could be served as the main indicators in evaluating the drought resistance of wild Poa genus. The mean annual precipitation of source land was negatively correla ted with comprehensive value, but it was not significant （p〈0.05）. The drought resistant capacities of the seven species were evaluated by standard deviation coefficient allocation weighted method, the seven species were thereby classified into three type： the first category was drought resisted, including P. pratensis, the second category was medium drought resisted, including P. dolichachyra, P. anqustifolia, P. cry mophila and P. poophaqorum, and the drought resistance of the third category was weak, including P. declinata and P, micrandra.