表油菜素内酯诱导南瓜幼苗抗疫病研究

采用叶面喷施的方法，研究了24-表油菜素内酯(24-Epibrassinolide,EBR)对南瓜疫病的诱抗作用及其生理机制。结果表明，EBR处理降低了南瓜幼苗疫病病情指数，最高降幅达29.0 %；喷施EBR使南瓜叶片中H2O2含量增加，丙二醛（MDA）含量下降，过氧化氢酶（CAT）活性增强，过氧化物酶（POD）活性先缓慢下降然后升高；接种疫霉菌后，EBR使H2O2和MDA含量缓慢增加，但EBRP处理与CP处理相比，MDA含量显著降低，CAT活性显著提高，POD活性显著降低；喷施EBR明显促进南瓜幼苗生长，即使在接种疫霉菌后，植株的长势也强于CP处理。表明EBR通过调节植物体内氧的代谢平衡，增强南瓜对疫病的抗性。

Studies on Resistance of Pumpkin Seedlings to Phytophthora capsici by Exogenous 24-Epibrassinolide Treatment

The induced resistance of pumpkin seedlings to Phytophthora capsici and its physiological mechanism were studied by 24-Epibrassinolide with foliar spray.The results showed that 24-Epibrassinolide increased H2O2 content,decreased MDA content,improved catalase(CAT)activities,peroxidase(POD)activities first decreased slowly then increased.After inoculated by Phytophthora capsici，the disease index of pumpkin seedlings decreased by 29 %,the contents of H2O2 and MDA increased slowly when plants were sprayed with EBR first,but the MDA content and POD activity were remarkably lower than CP treatment，CAT activity was significantly higher than CP treatment.EBR evidently promoted the growth of pumpkin seedling,the plant growth vigor was also stronger than CP treatment even during Phytophthora capsici infection.EBR kept the metabolism of active oxygen at a balanced level and increased pumpkin resistance to Phytophthora capsici.