Abstract: To explore the feasibility of preventing and controlling apple replant disease by biofumigation using Tagetes erecta power，and to study its effects on soil environment and physiological characteristics of Malus hupehensis Rehd. seedlings. A pot experiment was carried out，and the seedlings of Malus hupehensis Rehd. were planted in pots with old apple orchard soil. The experiment included 5 treatments，that was，the control（Replanted soil），0（Replanted soil + film mulching），0.05 %[Replanted soil + 0.05%（w/w）Tagetes erecta powder + film mulching]，0.2%（Replanted soil + 0.2% Tagetes erecta powder + film mulching），0.5%（Replanted soil + 0.5% Tagetes erecta powder + film mulching）. And the soil nutrient content，soil phenolic acid content，gene copies of Fusarium oxysporum，root respiration rate and antioxidant enzyme activity，leaf photosynthetic parameters and chlorophyll fluorescence parameters were measured. The results showed that treatment with 0.2% Tagetes erecta power could significantly increase soil nutrient content，reduce soil phenolic acids content，decrease gene copies of Fusarium oxysporum，increase root respiration rate and antioxidant enzyme activity，reduce MDA content；and could effectively alleviate the decrease of photosynthetic and fluorescence parameters caused by the replant disease，such as photosynthetic rate（Pn），the maximum photochemical efficiency of PSII（φPo），the actual photochemical efficiency（ΦPSII），the photochemical quenching（qP）and the number of reactive centers per unit area（RC/CSm），and change the OJIP curve shape. All the indicators of 0.05% and 0.5% were improved compared with the control，but the effect was not as good as that of 0.2% concentration. So the suitable concentration of Tagetes erecta biofumigation（0.2%）could improve soil environment，promote root growth，enhance the photosynthetic capacity and improve the energy distribution of M. hupehensis seedling leaves，and then alleviate the damage of PSII.

Key words: apple, Malus hupehensis, replant disease, Tagetes erecta, biofumigation, soil nutrient and phenolic acid content, photosynthetic and fluorescent parameters