外源水杨酸对低温胁迫下烤烟幼苗生理特性的影响

为揭示外源水杨酸对提高烤烟幼苗抗低温能力的生理效应，以云烟87为供试品种，运用人工气候培养箱模拟4℃低温，设置不同浓度(0、0.6、0.8、1.0和1.2mmol/L)水杨酸对烤烟幼苗连续3d进行叶面喷施预处理，随后进行连续5d的低温处理，以25℃、喷施蒸馏水作为对照，测定烤烟幼苗活性氧代谢、抗氧化酶活性、渗透调节物质含量和根系活力的影响。结果表明，低温胁迫下烤烟幼苗活性氧增加，膜脂过氧化程度加剧，抑制幼苗的生长发育。而外源水杨酸能够明显提高低温胁迫下烤烟幼苗的抗氧化酶活性，增加渗透调节物质含量，降低O₂^-·产生速率和MDA积累量，缓解低温胁迫对烤烟幼苗的损伤，增强其抗低温能力。

Effects of Exogenous Salicylic Acid on Physiological Characteristics of Flue-Cured Tobacco Seedlings under Low Temperature Stress

In order to reveal the physiological effects of exogenous salicylic acid on improving the low temperature resistance of flue-cured tobacco seedlings, Yunyan 87 was used as the material, and artificial climate incubator was used to simulate 4°C low temperature. Different concentrations (0, 0.6, 0.8, 1.0 and 1.2mmol/L) of salicylic acid were set up to pretreatment on flue-cured tobacco seedlings for three days, followed by five days of low temperature treatment. With 25°C and spraying distilled water as control, the effects of active oxygen metabolism, antioxidant enzyme activity, osmotic adjustment substance content and root activity of flue-cured tobacco seedlings were measured. The results showed that, under low temperature stress, the reactive oxygen species of flue-cured tobacco seedlings increased, and the degree of membrane lipid peroxidation increased, which inhibited the growth and development of seedlings. Exogenous salicylic acid could significantly improve the antioxidant enzyme activity of flue-cured tobacco seedlings under low temperature stress, increase the content of osmotic adjustment substances, reduce the O^-₂· production rate and MDA accumulation, alleviate the damage of low temperature stress on flue-cured tobacco seedlings, and enhance their low temperature resistance.