Effects of medium moisture on leaf lipid peroxidation and protective enzyme activities in grafted cucumber seedlings

The effects of medium moisture on leaf MDA content,membrane permeability,superoxide dismutase(SOD),peroxidase(POD),catalase(CAT) and ascorbate peroxidase(APX) activities in grafted seedlings(Cucurbita ficifolia as root stock)were investigated.The results showed that MDA content and membrane permeability of grafted cucumber seedlings increased as medium moisture reduced.The activity of SOD,POD,CAT and APX of grafted cucumber seedlings and self-grafted cucumber seedlings increased temporally and then decreased during water stress,while POD activity decreased continuously.MDA content and membrane permeability were higher and the enzyme activities were lower in self-grafted seedlings than in grafted ones under the same moisture gradient.The MDA content and membrane permeability of grafted seedlings were lower in intercropping than in single-standing.The results indicated that the big root volume of grafted seedlings brought about stronger adaptability to moderate drought,the grafted seedlings with larger roots showed advantages over self-grafted ones in water competition.