黑麦草幼苗在冻融及NaHCO_3复合胁迫下的生理响应

以冬牧70黑麦草幼苗为实验材料,考察黑麦草幼苗在单一人工模拟冻融胁迫(10,5,0,-5,0,5,10℃)及NaHCO_3复合胁迫下的生理响应机制.结果表明:在单一冻融胁迫下,黑麦草幼苗叶片中脯氨酸和丙二醛(MDA)的含量及过氧化氢酶(CAT)和超氧化物歧化酶(SOD)的活性均呈先升高后显著降低的变化趋势,过氧化物酶(POD)的活性呈先升高后缓慢降低的趋势;除CAT外,其他生理指标均在-5℃达到最大值,与其他温度下的活性相比存在显著性差异(P0.05);在复合胁迫处理条件下,生理指标呈"复合胁迫单一冻融胁迫对照"的规律;黑麦草幼苗叶片中蛋白质的质量比在0℃时达到最大值,复合胁迫和单一冻融组均高于对照组,即黑麦草幼苗在单一冻融胁迫及NaHCO_3复合胁迫下可快速提高抗氧化酶活性与渗透调节物质的质量比,以缓解胁迫导致的伤害,且复合胁迫对幼苗的影响更大.

Physiological Response of Ryegrass Seedlings underFreezing Thawing and Combined with NaHCO3 Stress

Using Dongmu 70 ryegrass seedlings as experimental mate rial, we investigated its physiological response mechanism under the single artificia l simulated freezing thawing stress (10,5,0,-5,0,5,10 ℃) and combined with NaH CO₃ stress. The results show that the content of proline and malondialdehyd e (MDA) and the activity of catalase (CAT) and superoxide dismutase (SOD) in the leaves of ryegrass seedlings increased firstly and then decreased significantly under a single freezing thawing stress, the activity of peroxidase (POD) increa sed firstly and then decreased slowly, except for CAT, other physiological index es reach the maximum value at -5 ℃, which compared with other temperatures ther e are significant differences (P<0.05). Under the condition of combined stre ss treatment, physiological indexes show the rule of combined stress>single stre ss>control. The mass ratio of protein in the leaves of ryegrass seedlings raech the maximum value at 0 ℃, and combined stress and single freezing thawing gro up are higher than those in control group. Thus, the ryegrass seedling under the single freezing thawing stress and combined with NaHCO₃ stress can rapidly i mprove the activities of antioxidant enzymes and the mass ratio of osmotic adjus tment substances to alleviate damage caused by stress, and the effects of combin ed stress on seedlings are greater than the single stress.