Abstract: The effect of NO on oxidative damage caused by shade was investigated in tall fescue (Festuca arundinacea‘Arid 3’) leaves. Tall fescue seedlings sprayed with NO donor (sodium nitroprusside, SNP) were subjected to 0%, 20%, 60%, 90% shade stress. Treatment of tall fescue leaves with 0.1 mM SNP before shade stress alleviated shade-induced membrane permeability, malondialdehyde contents. However, the activities of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT), as well as chlorophyll (Chl) content and proline accumulation in tall fescue leaves increased in the presence of SNP under shade stress. Moreover, the protective effect of NO varied according to shade time and intensity. Exogenous NO showed better protective effects under 20% and 60% shade, but a less influence under 90% shade. On the other hand, there was a significant difference between different exposure times. Treatments with SNP under 20%, 60% and 90% shade for two weeks showed the best effect. It could be concluded that NO might act as a signaling molecule to enhance antioxidant enzyme activities, thereby protecting tall fescue leaves from oxidative injures under shade stress. However, the protective effect of NO declined with the increases of treatment time and intensity.

Key words: Tall fescue, Shade stress, Nitric oxide, Antioxidant enzyme, Regulation mechanisim

摘要： 在不同遮阴胁迫下（20%遮阴、60%遮阴和90%遮阴），采用叶面喷施外源一氧化氮（NO）方法，研究了外源NO对遮阴胁迫下高羊茅瑞德3号（Festuca arundinacea ‘Arid 3’）的形态指标、叶绿素含量、膜透性、丙二醛（MDA）含量、抗氧化酶活性及脯氨酸含量的影响。结果表明：20%遮阴对高羊茅植株几乎没有伤害，而60%和90%遮阴的伤害作用较严重，并且随着遮阴时间的增加高羊茅受伤害程度加强。外源NO可以显著提高遮阴胁迫下高羊茅叶片的叶绿素含量，降低质膜相对透性的增加，减少膜质过氧化产物MDA含量的升高，促进脯氨酸的积累，提高超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）的活性。外源NO的保护作用随着遮阴时间与遮阴强度的增加而变化，外源NO对20%遮阴和60%遮阴的高羊茅效果较好，而对90%遮阴高羊茅效果较差；此外，随着遮阴时间增加，外源NO对不同遮阴强度高羊茅作用效果不同，处理14 d效果较好。综上表明，外源NO对遮阴胁迫下的高羊茅具有一定的保护作用，但是这种保护作用随着遮阴时间与遮阴强度的增加而下降。

关键词: 高羊茅, 遮阴胁迫, 一氧化氮, 抗氧化系统, 调控机理