节点文献
苗期紫花苜蓿（Medicago sativa）对干旱胁迫的适应机制研究
Study on Adaptive Mechanisms of Alfalfa(Medicago Sativa) in Drought Stress at Seedling Stage
【作者】 韩瑞宏；
【导师】 卢欣石；
【作者基本信息】 北京林业大学 ， 森林培育， 2006， 博士
【摘要】 本试验选择具有代表性并能真实反映植物抗旱性的17项形态指标及生长指标对国内外10个紫花苜蓿种质资源的抗旱性进行综合评价，根据评价结果挑选出强抗旱性、中抗旱性及弱抗旱性三个紫花苜蓿材料进行紫花苜蓿抗旱机制的研究，为探讨苜蓿抗旱机理积累资料，主要研究结果如下： 1．通过主成分分析及隶属函数分析，将17个差异显著的抗旱形态与生长指标综合为4个主成分即生物量因子、株型因子、根系因子和胁迫指数因子，10个紫花苜蓿种质资源的抗旱性由强到弱依次为：陇东、BL-02-388、敖汉、BL-02-312、BL-02-344、公农1号、中苜1号、BL-02-353、新疆大叶、BL-02-329。其中，选取抗旱性强(陇东)、中(公农1号)、弱(BL-02-329)的三个材料，进行下一步抗旱机理研究。 2．对干旱胁迫下陇东、公农1号、BL-02-329三种紫花苜蓿叶片活性氧清除机制的研究结果表明，干旱胁迫会造成紫花苜蓿叶片活性氧产生速率增大、丙二醛含量增多、细胞膜透性增大。与抗旱性弱的苜蓿相比，抗旱性强的苜蓿其叶片活性氧产生速率低，丙二醛含量积累少，细胞膜受到的破坏较轻，且复水后恢复程度好。干旱胁迫下，三种紫花苜蓿叶片SOD、POD两种保护酶活性增高、非酶抗氧化物质含量增多。抗旱性强的苜蓿酶系统与非酶系统内部协调性强。 3．对干旱胁迫下三种紫花苜蓿叶片水分代谢及部分渗透调节物质的研究表明，干旱胁迫使苜蓿叶片水势和叶片组织相对含水量降低，水分饱和亏缺及束缚水含量增加。抗旱性强的苜蓿叶水势降低幅度大，叶片组织含水量下降幅度及叶片水分饱和亏缺增加的幅度小，束缚水与自由水的比值增加幅度大，维持正常水分状况的能力强。同时叶片脯氨酸及可溶性糖两种主要渗透调节物质的含量增加，其中脯氨酸增加明显，在抗旱品种中成百倍的增加，可作为苜蓿抗旱鉴定的指标。陇东苜蓿在控水的第12天可溶性糖含量降低时，脯氨酸含量达到最大，脯氨酸在干旱后期的大量积累可能是可溶性糖下降的补偿策略。 4．在国内首次对干旱胁迫下紫花苜蓿的光合生理进行较为系统的研究，结果表明，干旱胁迫下三种紫花苜蓿净光合速率、蒸腾速率、气孔导度都有较大幅度的下降，气孔导度和蒸腾速率间呈极显著正相关。相对于抗旱性差的苜蓿，抗旱性强的苜蓿随着干旱胁迫程度的加深，净光合速率下降较慢。复水后三种紫花苜蓿净光合速率、蒸腾速率、气孔导度均有所上升，其中陇东苜蓿恢复的程度最大。研究表明，轻度水分
【Abstract】 Seventeen morphology indexes and growth indexes that can reflect plant drought resistance truly were chosen to comprehensively evaluate the drought resistance of 10 alfalfa germplasm resources both at home and abroad, on the basis of the results, three alfalfa germplasm resources were selected as strong drought-resistance medium drought-resistance and weak drought-resistance experiment materials to study the adaptive mechanisms of alfalfa under drought stress in order to accumulate data to investigate drought resistance mechanisms of alfalfa. The main results of research are as followings:1 .With principal components analysis and subordinate function analysis seventeen morphology indexes and growth indexes could be divided into 4 groups: biomass factor; plant morphological factor, root factor; stress index factor, the drought resistance’s order of alfalfa from better to worse is Longdong, BL-02-388, Aohan, BL-02-312, BL-02-344, Gongnong No 1, Zhongmu No 1, BL-02-353, XinjingDaye, BL-02-329. Strong drought -resistance （Longdong） medium drought-resistance （GongnongNo1） and weak drought -resistance （BL-02-329） were chosen for the study of drought resistance mechanisms.2.O2·-generation and clearing mechanism in the leaves of Longdong GongnongNol and BL-02-329 were studied and the results show: under drought stress, O2·- generation rate MDA content and damage of cell membrane increased. Campared with weak drought-resistance alfalfal there were low O2·- generation rate less accumulation of MDA content and lighter damage of cell membrane in the leaves of strong drought-resistance alfalfa when stressed by drought, and strong drought-resistance alfalfa can recovery faster after rewatering.at the same time SOD POD activity enhanced and antioxidation substance increased.There are higher endogenous coordination of antioxidation enzyme system and nonenzyme system in strong drought-resistance alfalfa.3.The results of study on water metabolism and osmotic adjustment substance in the leaves of three alfalfa show :the water potential water relative content water saturated deficit and bound water content increased under drought stress. There were higher decrease extent of