干旱胁迫后复水对烤烟生长及其生理特性的影响

  目的  为明确干旱胁迫后复水对烤烟生长及其生理基础的影响。  方法  采用盆栽试验方法，以耐旱型烤烟品种“豫烟6号”和水分敏感型“豫烟10号”为试验材料，设置正常供水、轻度干旱、中度干旱、轻度干旱后复水和中度干旱后复水5个处理，比较分析干旱胁迫后复水对烤烟生长及其生理特性的影响。  结果  （1）随着干旱的加剧，两个烤烟品种生长受到抑制，生理性能下降，株高、茎围、最大叶长、最大叶宽、最大叶面积、有效叶片数、根系干重和单株干重均降低或显著降低，叶绿素含量、净光合速率（P_n）、气孔导度（G_s）、蒸腾速率（T_r）、PSII最大光能转化效率（F_v/F_m）、PSⅡ实际光化学效率（Φ_PSⅡ）和光化学淬灭系数（qP）均显著降低，而非光化学猝灭系数（NPQ）、胞间二氧化碳浓度（C_i）、丙二醛（MDA）含量、超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性均显著增加；与正常供水相比，豫烟10号在干旱胁迫下各指标变化幅度大于豫烟6号，对干旱较敏感。（2）干旱胁迫后复水，与干旱处理结束时相比，两个烤烟品种生长得到明显恢复，光合作用增强，抗氧化系统平衡得到明显改善。豫烟10号在干旱胁迫后复水各指标变化幅度均大于豫烟6号，干旱胁迫后复水恢复较好。  结论  在干旱胁迫下，两个烤烟品种的生长和生理性能均受到不同程度的抑制，且均与正常供水处理间差异显著；复水后，两个烤烟品种的生长及其生理性能均得到不同程度的恢复，其多数指标均以中度干旱胁迫后复水处理恢复较好，且与正常供水处理无显著差异。 

Effect of rehydration after drought stress on the growth and physiological characteristics of flue-cured tobacco

  Objective  This study aims to understand the effect of rehydration after drought stress on the growth and physiological basis of flue-cured tobacco.  Methods  By taking drought-tolerant flue-cured tobacco variety "Yuyan 6" and moisture-sensitive flue-cured tobacco variety "Yuyan 10" as experimental materials, the effects of rehydration after drought stress on the growth and physiological characteristics of flue-cured tobacco was investigated by pot experiment under five treatments of normal water supply, mild drought, moderate drought, rehydration after mild drought and rehydration after moderate drought.  Results  (1) With the aggravation of drought, the growth of two flue-cured tobacco varieties was inhibited, their physiological performance was decreased, and the plant height, stem circumference, maximum leaf length, maximum leaf width, maximum leaf area, effective leaf number, root dry weight and dry weight per plant were all decreased or significantly decreased, and the chlorophyll content, net photosynthetic rate (P_n), stomatal conductance (G_s) and transpiration rate (T_r), maximum light energy conversion efficiency of PSII (F_v/F_m), actual photochemical efficiency of PSII, (Φ_PSⅡ) and photochemical quenching coefficient (qP) in leaves were significantly reduced. In contrast, non-photochemical quenching coefficient (NPQ), intercellular carbon dioxide concentration (C_i), MDA content, superoxide dismutase (SOD) activity, peroxidase (POD) activity and catalase (CAT) activity were increased significantly. Compared with normal water supply, Yuyan 10 is more sensitive to drought than Yuyan 6 under drought stress. (2) By rehydration after drought stress, the growth of two flue-cured tobacco varieties was obviously restored, the photosynthesis was enhanced, and the balance of antioxidant system was obviously improved compared with the end of drought treatment. After drought stress, Yuyan No.10 has a larger change range of rehydration indexes than Yuyan No.6. After drought stress, the rehydration recovery is better.  Conclusion  Under drought stress, the growth and physiological properties of the two flue-cured tobacco varieties were inhibited in different degrees, showing significant differences withnormal water supply treatment. After rehydration, the growth and physiological properties of the two flue-cured tobacco varieties were restored to different degrees, and most of the indexes were recovered well after rehydration under moderate drought stress, showing no significant difference with normal water supply.