为探索营养生长与生殖生长并进时期玉米叶片抗氧化生理对高温胁迫的响应特征,以郑单958(ZD958)和先玉335(XY335)为试验材料,于玉米第9片叶完全展开至抽雄期,每天8:30-17:30进行人工模拟增温处理,研究高温胁迫下玉米叶片膜透性、抗氧化酶活性以及渗透调节物质的动态变化。结果表明：(1)成熟玉米叶的相对电导率大于幼嫩叶,高温胁迫导致玉米叶片相对电导率增加,ZD958成熟叶的增加幅度大于幼嫩叶,XY335成熟叶的增加幅度小于幼嫩叶。(2)高温处理期内,抗氧化保护酶活性变化在不同品种不同成熟度叶片之间存在较大差异。在高温处理早期阶段,ZD958成熟叶SOD、POD和CAT活性均增加并高于对照,后期阶段增幅放缓,甚至低于对照；而幼嫩叶三种保护酶活性在高温处理前期阶段大多与对照无明显差异,后期则明显升高。高温处理期内,XY335成熟叶CAT活性均大于或显著大于对照,SOD和POD活性多低于或显著低于对照；而幼嫩叶三种酶的活性均大于或显著大于对照。(3)成熟玉米叶的MDA含量大于幼嫩叶,高温胁迫导致玉米叶片MDA含量增加,ZD958成熟叶的增加幅度大于幼嫩叶,XY335成熟叶的增加幅度小于幼嫩叶。(4)与对照相比较,高温胁迫下,玉米叶中的可溶性蛋白含量无显著性变化；在ZD958成熟叶和幼嫩叶中可溶性糖含量均呈现先升后降的趋势,在XY335成熟叶中表现为升高趋势,幼嫩叶则呈现升-降-升-降的变化；游离性脯氨酸在成熟叶中呈现降-升-降的变化,ZD958幼嫩叶呈现先升后降的趋势,XY335幼嫩叶始终大于或显著大于对照。结果提示,不同品种不同成熟度叶片对高温胁迫的敏感性不同。XY335叶片的敏感性高于ZD958,ZD958成熟叶的敏感性大于幼嫩叶,XY335幼嫩叶的敏感性大于成熟叶。
英文摘要:
In order to explore response of antioxidative physiology to high temperature in maize leaf during the growth progress of vegetative and reproductive, using two maize hybrids of Zhengdan958(ZD958) and Xianyu335(XY335), from the 9th leaf fully expanded to tasseling stage, plants were given a high temperature treatment(T) from 8:30 to 17:30 daily in an artificial simulation heat device, studying the dynamics of membrane permeability, activity of antioxidant enzymes and osmotic regulation substances of maize leaf under heat stress. The results show that: (1)The relative electrical conductivity of mature leaves is higher than the young leaves and increasing during high temperature stress, the increase extent was higher in mature leaves than in young leaves of ZD958, while it was lower in mature leaves than in young leaves of XY335. (2) The superoxide dismutase(SOD), peroxidase(POD) and catalase(CAT) show different trends among maize varieties and leaves under heat stress. In the early stage of high temperature treatment, compared with control, the activities of SOD , POD and CAT all increased in mature leaves of ZD958, then decreased even lower than control. Contrary to the mature leaves, the three enzymes activities of the young leaves increased in the later stage of high temperature treatment. In mature leaves of XY335, the activities of SOD and POD decreased while increased for CAT. In the young leaves, the three enzymes activities increased or increased significantly. (3)The content of MDA was higher in mature leaves?than in young leaves and increasing as heat stress, the increase extent was higher in mature leaves than in young leaves of ZD958 while it was opposite in XY335. (4) Under high temperature stress, compared with control, there were no significant changes of soluble protein in mature leaves?or young leaves, the contents of soluble sugar increased first and decreased afterwards in mature leaves and young leaves of ZD958, increased in mature leaves of XY335, and showed a change of increased-decreased-increased-decreased in young leaves of XY335, and the content of free proline present a trend of decreased-increased-decreased in mature leaves, and increased first and decreased afterwards in young leaves of ZD958 while increased in XY335. These results suggest that different varieties and maturity leaves of maize have different sensitivity to heat stress. The sensitive of leaf to high temperature is higher in XY335 than in ZD958, and the sensitive to high temperature is higher in mature leaves than in young leaves of ZD958 while it is opposite in XY335.
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