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以‘Midnight’和‘Brilliant’两个草地早熟禾(Poapratensis)品种为试材,研究叶片渗透势、膜脂肪酸成分变化以及抗氧化酶对高温胁迫(35/30℃,昼/夜)的响应。高温胁迫下,‘Midnight’草地早熟禾草坪外观质量显著高于‘Brilliant’;随胁迫时间延长,‘Midnight’叶片的渗透势不断下降,而‘Brilliant’除在前5d有一定程度下降外,而后基本处于不变,‘Midnight’保持更高的相对含水量;两品种亚麻酸(18︰3)含量不断下降,亚油酸(18︰2)和棕榈酸(16︰0)不断增加,即脂肪酸饱和水平增加,‘Midnight’比‘Brilliant’含有更高的亚麻酸和棕榈油酸(16︰1),更低的棕榈酸和硬脂酸(18︰0),因而伴随着更高的双键指数(DBI);‘Brilliant’的MDA含量在胁迫10d后上升加快,胁迫25d结束时其含量为‘Midnight’的1.6倍,与之相对应的则是‘Midnight’的SOD酶活性显著高于‘Brilliant’,电解质渗透率显著低于‘Brilliant’。以上结果表明,‘Midnight’较强的渗透调节能力,较高的SOD酶活性,减轻了膜脂过氧化程度,有效保护了细胞膜稳定性,因而缓解了高温胁迫下的水分和氧化压力,表现出较强的耐热性。同时,‘Midnight’具有避免膜脂饱和程度剧烈变化的能力,也可能与耐热性较强有关。
Using two varieties of ’Midnight’ and ’Brilliant’, Poapratensis as test material, the leaf osmotic potential, the changes of membrane fatty acid composition and the responses of antioxidant enzymes to high temperature stress (35/30 ℃, day / night) were studied. Under high temperature stress, the appearance quality of ’Midnight’ Kentucky bluegrass was significantly higher than that of ’Brilliant’. With the prolongation of stress time, the osmotic potential of ’Midnight’ declined continuously, while ’Brilliant’ decreased to a certain extent except the first 5 days, The content of linolenic acid (18︰3) in two cultivars decreased continuously, the content of linoleic acid (18︰2) and palmitic acid (16︰0) kept increasing, namely, the content of fatty acids Saturation levels increase. ’Midnight’ contains higher linolenic and palmitoleic acids (16: 1), lower palmitic and stearic acids (18: 0) than ’Brilliant’ and is therefore accompanied by higher double bonds (DBI). The content of MDA in ’Brilliant’ increased 10 d after stress and reached 1.6 times that of ’Midnight’ at the end of 25 d. The activity of SOD in ’Midnight’ was significantly higher than that of ’ Brilliant ’, the electrolyte permeability is significantly lower than that of’ Brilliant ’. The above results show that ’Midnight’ has stronger ability of osmotic adjustment, higher activity of SOD, reduced membrane lipid peroxidation and effectively protected the stability of cell membrane, thus relieving the moisture and oxidative stress under high temperature stress and showing Strong heat resistance. At the same time, ’Midnight’ has the ability to avoid dramatic changes in membrane lipid saturation, may also be related to strong heat resistance.