【摘要】 在轻度干旱时烤烟体内过氧化物酶（POD）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性以及根系脱氢酶活性均有所增强，这些生理生化变化都是烟草对干旱胁迫的适应性反应。随着干旱时间的延长和胁迫程度加剧，上述酶活性出现不同程度的降低。这时叶片细胞膜透性增大，丙二醛（MDA）大量积累，叶片生长停滞并出现可见旱害。氮肥形态不仅会对正常生长的烟草产生不同影响，而且使在干旱胁迫下烟草的生长差异更加显著。NO3－N处理的烟株在干旱时，抗旱性得到提高，经测定，上述抗旱指标明显优于尿素（UREA）、NH4－N处理。在干旱胁迫下NO3－N处理能较长时间地保持内源保护酶和根系脱氢酶的活性，在严重干旱时烟叶的细胞膜透性和MDA积累得到有效控制，叶片在干旱时的生长损失得到缓解。更多还原

【Abstract】 When stressed by drought, some physiological and chemical changes took place in flue－cured tobacco． The activities of POD, SOD, CAT and root dehydrogenase were all strengthened under light drought． With prolong and intensifying of drought, their activities decreased differently, the permeability of membrane increased and MDA was greatly accumulated, the growth of tobacco stagnated and drought harm appeared． The results showed that nitrogenous fertilizer forms not only affected the growth of normal tobacco, but also increased the growth difference of tobacco under drought stress． NO3－N could improve drought resistance of tobacco, it was better than urea and NH4－N． NO3－N could keep the activities of these protective endoenzymes in a longer time, hold the permeability of membrane and the accumulation of MDA, and relieve the growth loss of tobacco under drought stress．更多还原