苗期低温胁迫对扬麦16叶片抗氧化酶和渗透调节物质的影响

以扬麦16为试验材料, 利用人工气候箱模拟低温逆境, 研究-4℃、-6℃和-8℃低温胁迫对小麦苗期生长和叶片生理特性的影响。结果表明, 随着处理温度的降低、胁迫时间的延长, 小麦植株由叶尖萎蔫变黄的2、3级冻害加重至叶片全枯的4级冻害, 甚至大部分茎蘖冻死的5级冻害, –4℃和–6℃处理24 h没有发生4级及以上冻害。–8℃处理24 h和48 h后植株5级冻害比例显著增加, 植株死亡率分别为16.7%和39.6%。低温胁迫初期小麦叶片中SOD、POD和CAT活性均呈上升趋势, 随胁迫程度加重, SOD最先表现出下降趋势, POD和CAT变化稍缓, MDA含量增加。苗期低温胁迫使叶片中游离脯氨酸、可溶性蛋白和可溶性糖含量明显高于对照, 且随温度的降低和处理时间的延长呈上升趋势, 表现出对低温逆境的适应性。

Effect of Low Temperature at Seedling Stage on Antioxidation Enzymes and Cytoplasmic Osmoticum of Leaves in Wheat Cultivar Yangmai 16

Morphological, physiological and biochemical changes in wheat seedlings (cv. Yangmai 16) under low temperature treatments (-4°C, -6°C, and -8°C) were studied by means of artificial temperature-controlled phytotron. Severer freezing-injured plants were observed in treatments with lower temperature and longer stress. The symptoms of injury were that the top of leaves became yellow and wilting (the second and third grade of freezing injury), then the whole leaves were all wilting (the fourth grade of freezing injury), and main stems and most of tillers were finally dead (the fifth grade of freezing injury). No plants showed freezing injury greater than the third grade in treatments of -4°C and -6°C for 24 h. However, the treatments of -8°C for 24 h and 48 h resulted in 16.7% and 39.6% of plant being frozen to death, respectively. The activities of superoxide dismutase (SOD), catalase (CAT), and peroxide dismutase (POD) in the second leaf from the top increased at the beginning of low temperature treatments, and with the increasing of stressSOD activity declined. The contents of malonaldehyde (MDA), proline, soluble sugar, and soluble protein were significantly increased in treatments with lower temperature and longer stress. These physiological and biochemical changes may help to alleviate the low-temperature injury to wheat plants.