Research On The Effect Of EBR Alleviating Continuous Cropping Obstacles In Melon Seedlings

In this study,a kind of melons named ’Jin Mi’ was utilized as materials,5 years,15 years of successive cropping soil was chosen to pot it,and non-successive cropping soil was used as control to research the effects of Exogenous 24-epibrassinolide(24-epibrassinolide,Acronym EBR)on the growth and development,antioxidant enzyme systems and photosynthetic characteristics of it under successive cropping stress.The results are as following:1.Under continuous cropping stress,the leaf area,the plant height,the fresh weight,and the dry weight of melon decreased significantly,and the longer times of successive cropping with the greater reduction.After sprayed EBR as a treatment,the leaf area,the plant height,the fresh weight and the dry weight increased significantly.2.Under continuous cropping stress,the activity of POD,SOD and CAT in melon seedlings showed decreasing trend,and the activity of antioxidant enzymes dropped to the lowest after 15 years of continuous cropping stress.After the treatment of EBR,the activities of antioxidant enzyme had been recovered.Meanwhile,the content of soluble protein decreased,of Pro and MDA and membrane permeability increased significantly in melon seedlings.After the spraying of EBR on melon leaves,the content of soluble protein content increased,of Pro,MDA and membrane permeability were significantly reduced.3.Under continuous cropping stress,the related photosynthetic indexes decreased significantly in melon seedlings,and the longer times with the greater reduction.The contents of Chla,Chlb and total chlorophyll were reduced significantly.Pn,Gs and Tr all decreased significantly,otherwise,Ci increased.Fv/Fm,ΦPSⅡ,qP decreased significantly.Jmax,Rubisco and the activities of 1,5-December ribulose phosphate carboxylase/oxygenase were significantly reduced.Exogenous EBR increased the contents of Chla,Chlb and total chlorophyll in leaves,increased Pn,Gs,Tr,decreased Ci significantly,increased Fv/Fm,Φ PS Ⅱ,qP,Jmax,maximum Rubisco and the activities of Rubisco significantly.The results showed that exogenous EBR could improve the performance of the leaf Photosynthetic,alleviate the continuous cropping obstacles in melon seedlings to some extent.