Abstract:

Effects of Allium fistulosum L. and apple seedlings mixed cropping on the replant soil environment and growth of Malus hupehensis Rehd. seedlings were studied under pot condition. Results showed that mixed cropping enhanced Malus hupeheusis Rehd. seedlings biomass. Plant height，ground diameter，fresh weight and dry weight were 1.42，1.67，3.63 and 2.99 times larger than the control group. The root respiration rate of Malus hupehensis Rehd. seedlings was significantly improved. Activities of antioxidant enzymes，such as superoxide dismutase（SOD），catalase（CAT）and peroxidase（POD）were 1.58，2.74，2.41 and 6.79 times higher than the control group. The activities of soil enzymes including  urease，invertase，phosphatase and catalase were significantly improved. The activities of soil enzymes in mixed cropping were better than in lime nitrogen，and after that was methyl bromide and apple replant in order. Numbers of bacteria and actinomycete were 2.44 and 1.79 times more than the control group and numbers of fungi dropped by 69.4%. The ratio of bacteria to fungi in different soils was as follows：methyl bromide > mixed cropping > lime nitrogen > replanted soil. A. fistulosum L. and apple seedlings mixed cropping significantly improved margalef index，Shannon’s index，pielou index and decreased simpson index. The number of Fusarium oxysporum was reduced significantly compared with the control group. In conclusion，A. fistulosum L. and apple seedlings mixed cropping decreased the number of fungi and increased that of bacteria，could reduce apple replant disease.

Key words: Malus hupehensis , Allium fistulosum , mixed cropping , soil environment , apple replant