不同时期环割对上部烟叶生长发育及质量的影响

为探究不同时期环割对烤烟上部烟叶生长发育及质量的影响，以云烟87为试验材料，分别设打顶后环割（T1）、下部叶采收后环割（T2）、中部叶采收后环割（T3）3个处理，以不环割烟株作为对照，对上部烟叶农艺性状、光合参数、糖代谢指标、碳氮代谢关键酶、氧化胁迫指标、化学成分、烤后感官质量进行测定分析。结果表明，下部叶采收后环割（T2）能够促进烟叶开片，长宽比降低7.90%，叶面积提升6.53%；叶片光合作用受到抑制，胞间CO₂浓度提升16.48%，蒸腾速率下降20.26%。环割处理不同程度地抑制叶片中SOD、POD、CAT活性，提高烟叶中MDA和H₂O₂含量，促进叶片衰老。T1、T2处理显著提高α淀粉酶、β淀粉酶、总淀粉酶和NI活性，降低叶片NR活性，显著降低烤后叶片烟碱和蛋白质含量，烤后烟叶香气质和香气量提升，余味改善，感官质量提高。以下部叶采收后环割对烟叶质量的改善效果最优。

Effects of Girdling at Different Stages on Growth and Development and Quality of Upper Tobacco Leaves

To study the effect of girding on growth and development, and quality of upper tobacco leaves of flue-cured tobacco, Yunyan 87 was used as the test material, and girdling after topping (T1), girdling after harvesting the lower leaves (T2), and girdling after harvesting the middle leaves (T3) were used as test treatments, with ungirdling plants as controls to determine and analyze the agronomic traits, photosynthetic parameters, sugar metabolism indexes, key enzymes of carbon and nitrogen metabolism, oxidative stress indexes, chemical routines, and sensory quality of the upper tobacco leaves. The results showed that girdling after harvesting the lower leaves (T2) promoted the opening of tobacco leaves, reduced the aspect ratio by 7.90%, increased the leaf area by 6.53%, inhibited photosynthesis, promoted intercellular CO₂ concentration by 16.48%, and reduced transpiration rate by 20.26%. Girdling treatments inhibited the activities of SOD, POD and CAT, increased the content of MDA and H₂O₂, and promoted leaf aging in varying degrees. T1 and T2 significantly promoted the activities of alapha amylase, beta amylase, total amylase and NI, but reduced the NR activity as well as the content of nicotine and proteins, improved the aroma quality, aroma amount, the aftertaste and sensory quality. Girdling after harvesting the lower leaves had the best effect on the upper leaves.