叶面喷施2,4-表油菜素内酯对烟草抗旱性的影响

为探讨外源2，4-表油菜素内酯（EBR）增强烟草幼苗抗旱能力的作用机理，以不同抗旱性烟草品种豫烟12号和豫烟10号为材料，采用水培法，研究干旱胁迫下叶面喷施外源EBR对烟草幼苗的影响。结果表明，干旱胁迫下，豫烟12号和豫烟10号幼苗生长受到抑制，叶片细胞活性氧和MDA含量增加，叶绿素遭到破坏，光合速率降低。喷施外源EBR能够显著促进干旱胁迫下烟草幼苗的生长和根系发育，叶片抗氧化酶（SOD、POD、CAT）活性提高，O₂^-产生速率和MDA含量降低，同时增加了叶绿素的含量，提高了光合速率。与豫烟12号相比，干旱对豫烟10号的影响较大，而喷施外源EBR均能降低干旱对两品种幼苗的伤害。喷施外源EBR能够促进根系形态发育，提高抗氧化酶活性，降低活性氧积累和膜质过氧化水平，提高光合能力，增强烟草的抗旱能力。

Effect of Leaf Spray 2,4-Epibrassinolide on Drought Resistance of Tobacco

In order to explore the function and mechanism of 2,4-epibrassinolide (EBR) in strengthening the ability of tobacco seedlings to resist drought, drought resistant cultivar Yuyan12 and drought sensitive cultivar Yuyan10 were grown under drought stress, and the effects of 2,4-epibrassinolide on growth of tobacco seedlings under drought stress were investigated by hydroponic experiments. The results showed that under drought stress, the growth of seedlings of Yuyan 12 and Yuyan 10 was inhibited, the O₂^- production rate and MDA contents in leaves of tobacco seedlings were increased, the Chlorophyll was destroyed, and the Photosynthetic rate was reduced. Under stress conditions, foliar spraying of EBR could significantly promote the growth and root development, effectively enhance the activities of antioxidase, and decrease the contents of superoxide anion, hydrogen peroxide and MDA. Meanwhile, the content of chlorophyll and the photosynthetic rate were increased. Compared with Yuyan12, drought stress had a greater influence on Yunyan10, but exogenous EBR could reduce the damage caused by drought on both varieties. Spraying exogenous EBR could promote the morphological development of root system, improve the activities of antioxidant enzymes, reduce the levels of reactive oxygen accumulation and membrane peroxidation, improve the photosynthetic ability, and enhance the drought resistance of tobacco.