中文摘要：

于2005—2006年在南京农业大学卫岗试验站进行盆栽试验,设置正常灌水（土壤含水量为田间持水量的75%左右）和棉花花铃期土壤短期干旱处理（将正常灌水的棉花自然干旱持续8d,以棉株出现萎蔫症状为标准,之后复水至正常灌水水平）,每个处理再设置3个氮素水平（0、3.73、7.46gNpot^-1,分别相当于0、240、480kg Nhm-2）,研究氮素对花铃期干旱及复水后棉花叶片内源保护酶活性和内源激素含量的影响。结果表明,花铃期短期干旱显著降低棉花叶片凌晨叶水势。在干旱结束时,干旱处理棉花叶片可溶性蛋白含量与过氧化氢酶（CAT）活性显著降低、超氧化物歧化酶（SOD）和过氧化物酶（POD）活性提高、丙二醛（MDA）含量增加,内源脱落酸（ABA）和生长素（IAA）含量升高、细胞分裂素（ZR）和赤霉素（GA）的含量降低,ZR/ABA、IAA/ABA、GA/ABA均降低,其叶片净光合速率（Pn）亦显著低于正常灌水处理。花铃期土壤干旱下施氮可提高可溶性蛋白含量、SOD与POD活性,以240kg Nhm^-2最有利于提高棉花叶片Pn,该处理CAT活性最高,MDA含量最低;ABA含量最低,而ZR、IAA、GA的含量以及ZR/ABA、IAA/ABA、GA/ABA最高。施氮不足（0kg Nhm^-2）或过量（480kg Nhm^-2）均表现出相反的趋势。到复水后第10天,干旱处理棉花叶片的内源保护酶活性可迅速恢复到正常灌水水平,其MDA含量与正常灌水处理的差异较小;但其ABA含量明显低于正常灌水处理,ZR、IAA、GA含量以及ZR/ABA、IAA/ABA、GA/ABA却显著高于正常灌水处理。并且施氮有利于提高复水后干旱处理棉花叶片的内源保护酶活性,降低细胞膜脂过氧化程度,降低ABA含量,增大ZR、IAA、GA含量以及ZR/ABA、IAA/ABA、GA/ABA,相比而言,复水后以480kg Nhm-2最有利于提高棉花叶片Pn。

英文摘要：

The flowering and boll-forming stage is the key period for significantly inhibits cotton development and reduces final productivity. cotton yield. Short-term drought stress during this stage Nitrogen application plays an important role in alleviating the adverse effects of dry soil on plant development. The objective of this study was to investigate the effects of nitrogen on plant resistance to soil drought in terms of the changes of antioxidant enzyme activities and endogenous hormone contents in cotton leaf under short-term drought stress （withholding water for eight days then re-watering）. Cotton plants were grown in pots with three N application levels （0, 3.73, and 7.46 g N pot1, equivalent to 0, 240, and 480 kg N ha^-1, respectively）. Leaf water potential and soil relative water content decreased with increasing N supply at the end of soil drought stress period. At the same time, drought stress significantly increased SOD and POD activities, MDA and ABA contents in cotton leaf, but reduced CAT activity, soluble protein, ZR, and GA contents, as well as ZR/ABA, IAA/ABA, and GA/ABA. Under soil drought, CAT activity, soluble protein, ZR, IAA, and GA contents, ZR/ABA, IAA/ABA, GA/ABA, and net photosynthetic rate （P,） in 240 kg N ha^-1 treatment were the highest among the three nitrogen treatments, but MDA content and ABA content in 240 kg N ha^-1 treatment was the lowest. These results suggested that 240 kg N ha^-l was the optimal nitrogen application rate under short-term soil drought in this experiments, but deficient （0 kg N ha^-1） and excessive （480 kg N ha^-1） nitrogen supply were of disadvantage to the antioxidant enzyme activities, endogenous hormone contents and photosynthesis. Nitrogen affected antioxidant enzyme activities and endogenous hormone contents not only under water stress but also under re-watering after drought stress. At the 10th day after soil re-watering, there was no difference in SOD and CAT activities, MDA content and P, between treatments with soil drought and wel