外源水杨酸对低温胁迫下低温敏感性不同的烤烟品种烟叶生理特性的影响

  目的  探究低温胁迫下外源水杨酸对低温敏感型不同烤烟品种叶片生理特性的影响，并筛选最佳外源水杨酸的缓解浓度。  方法  以低温不敏感型品种红花大金元及低温敏感型品种K326为材料，通过盆栽试验研究不同浓度外源水杨酸对4℃低温胁迫下红花大金元和K326叶片相对电导率（REC）、丙二醛（MDA）含量、抗氧化酶活性、渗透调节物质含量及多酚代谢的影响。  结果  低温胁迫下，2个低温敏感性不同的烤烟品种的相对电导率、丙二醛含量、多酚氧化酶活性及苯丙氨酸解氨酶活性均显著上升，其中，K326的丙二醛含量上升幅度远大于红花大金元，达94.07%；而3个抗氧化酶活性均被显著降低，K326的可溶性糖含量及总酚含量、红花大金元的可溶性蛋白含量均显著上升。施加外源水杨酸后，K326及红花大金元的叶片相对电导率及丙二醛含量均显著降低，而3个抗氧化酶活性及苯丙氨酸解氨酶活性均显著上升，红花大金元的可溶性糖含量及可溶性蛋白含量、K326的总酚含量均显著上升；当外源水杨酸浓度为50~100 mg/L时对各个指标的缓解效果较好。  结论  外源水杨酸浓度50 mg/L处理对红花大金元及K326的缓解效果均达到最佳。 

Effects of exogenous salicylic acid on physiological characteristics of flue-cured tobacco leaves with low temperature sensitivity under low temperature stress

  Objective  This study aims to explore the effects of exogenous salicylic acid on physiological characteristics of flue-cured tobacco leaves with low temperature sensitivity under low temperature stress, and to screen the optimal addition concentration of exogenous salicylic acid.  Methods  A pot experiment was conducted with cold-tolerant variety Hongda and cold-sensitive variety K326 as materials. The effects of different concentrations of exogenous salicylic acid on relative electrical conductivity, malondialdehyde content, antioxidant enzyme activity, osmotic regulation substance content and polyphenol metabolism of tobacco leaves under low temperature stress at 4 ℃ were studied.  Results  The results showed that low temperature stress significantly increased relative electrical conductivity, malondialdehyde content, activity of PPO and PAL, and decreased antioxidant enzyme activity. Among them, the content of MDA in flue-cured tobacco variety K326 increased significantly by 94.07%, which was significantly higher than that of Hongda. Then, the contents of soluble sugar and total phenol of K326 and the Hongda'ssoluble protein content were increased significantly. After the application of exogenous salicylic acid, the relative conductivity and MDA content decreased significantly, while the activities of three antioxidant enzymes and PAL increased significantly. The contents of soluble sugar and soluble protein of Hongda and the total phenol content of K326 increased significantly. When the concentration of exogenous salicylic acid was 50~100 mg/L, the remission effect were better.  Conclusion  When the concentration of exogenous salicylic acid was 50mg/L, the mitigation effect on the two varieties was the best.