| The experiment was carried out at the National Apple Engineering Center Experimental Station of Shandong AgricuLtural University South Campus in 2014 and 2015. We choosed the Malus hupehensis Rehd. seedlings as experimental material, and explored the effect of carbendazim and bio-organic fertilizer in potted condition. The aim of this experiment was to measure whether the combination of carbendazim and bio-organic fertilizer cou Ld replace the methyl bromide fumigation in alleviating the apple replant disease. Five treatments were set up: continuous cropping control, methyl bromide fumigation, carbendazim, bio-organic fertilizer, carbendazim and bio-organic fertilizer. The effect of carbendazim and bio-organic fertilizer on biomass, root respiration rate, soil microorganism, soil enzyme activity and root protective enzyme of Malus hupehensis Rehd. seedlings were studied. The main resu Lts were as follows:1. Carbendazim and microbial bio-organic fertilizer couLd improve the biomass of Malus hupehensis Rehd. Seedlings, and the effect of carbendazim and bio-organic fertilizer combined application was the best. Compared with the control, in August carbendazim and bio-organic fertilizer combination increased plant hight, stem diameter, fresh weight and dry weight by 37.93%, 36.09%, 138.89%, and 173.02%, respectively, and there are no significant difference between the combination treatment and methyl bromide fumigation.2. Compared with the control, the treatment of methyl bromide fumigation, carbendazim, bio-organic fertilizer, combined application of carbendazim and bio-organic fertilizer have changed the number of soil bacteria, fungi and the fungal community structure. Bio-organic fertilizer, combined application of carbendazim and bio-organic fertilizer have significantly increased the amount of bacteria in the soil, reduced the number of fungi, and so increased the ratio of bacteria to fungi. The soil bacteria in two treatments increased by 444.44% and 369.44%, fungi decreased by 43.08% and 75.39%, and the ratio of bacteria to fungi increased by 856.46%, 1807.12% in August. The soil fungal community structure have changed. The similarity coefficient was between 0.603 and 0.512 in the treatment of methyl bromide fumigation and continuous cropping control, which was the moderately similar. The similarity coefficient was between 0.733 and 0.794 in the treatment of combined application of carbendazim and bio-organic fertilizer, which was followed in the middle and very similar. Combined application of carbendazim and bio-organic fertilizer had higher simpson index and lower shannon index, pielou index and margalef index.3. Different treatments have changed the activity of main enzymes in soil. Urease, catalase, neutral phosphatase, and invertase activities of bio-organic fertilizer, combined application of carbendazim and bio-organic fertilizer were higher than that of in the treatment of methyl bromide fumigation and carbendazim. In August, the urease, catalase, neutral phosphatase and invertase of combined application of carbendazim and bio-organic fertilizer were increased by 226.32%, 91.81%, 153.18%, compared with continuous cropping control.4. Different treatments have increased the root respiration rate of Malus hupehensis Rehd. Seedlings In Ju Ly and August, the order of root respiration rate of Malus hupehensis Rehd. Seedlings was the methyl bromide fumigation, combined application treatment of carbendazim and bio-organic fertilizer followed, then the treatment of bio-organic fertilizer. In September, the root respiration rate in treatment of carbendazim and bio-organic fertilizer was higher than the others, increased by 72% compared with control, and more the other treatments did not reach significant difference.5. Different treatments have changed the activity of protective enzymes in root of seedlings. Compared with the control, the SOD, POD, CAT activity of the treatment of methyl bromide fumigation, bio-organic fertilizer, combined application of carbendazim and bio-organic fertilizer were increased significantly. Among these three treatments, the SOD activity increased by 39.08%, 17.24%, 46.36%, the POD activity increased by 46.36%, 85.19%, 114.81%, and the CAT activity increased by 130.04%, 76.38%, 82.96% in August, respectively.6. Combined application of carbendazim and bio-organic fertilizercan was better to improve the soil microbial community structure, improve the soil enzyme activity, increase root activity of protective enzyme, promote root growth, and alleviate continuous cropping obstacle of Malus hupehensis Rehd. seedlings. The mitigation effect of carbendazim and bio-organic fertilizercan combined application was close to methyl bromide fumigation treatment. |
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