| Continuous cropping obstacle is one of the problems in renewal process of apple orchard,so it is of great significance to explore effective measures to alleviate the obstacle.At present,biological control measures such as microbiological fertilizer are gradually applied to control of various soil diseases due to advantages of environmental protection,obvious soil improvement effect and easier commercialization.The experiment made Penicillium cyclopium D12,Trichoderma harzianum,and Penicillium oxalicum A1 into microbiological fertilizers.Apple rootstocks-Malus hupehensis Rehd.seedlings were used as test materials.The effects of three types of fertilizers on soil environment and continuous cropping of Malus hupehensis Rehd.Seedlings were investigated under replant condition.Results were as follows,1.The application of three types of fertilizers could increase the number of soil bacteria and reduce the number of fungi.The results in August 2018 and August 2019 showed that in August 2018,compared with apple replanted orchard soil(CK1),the number of fungi decreased by 42.22%,73.33% and 51.11% and the number of bacteria increased by 60.00%,96.67% and 83.33% after the application of Penicillium cyclopium D12 fertilizer(T1),Trichoderma harzianum fertilizer(T2)and Penicillium oxalicum A1 fertilizer(T3).In August2019,the application of T2 showed a significant performance.Compared with CK1,the number of bacteria increased by 83.58% and the number of fungi decreased by 58.45%.2.The determination of Fusarium oxysporum and Fusarium moniliforme in soil by realtime quantitative PCR showed that the copy number of F.oxysporum and F.moniliform genes in CK1 was the highest in 2018 and 2019.In August 2018,compared with CK1,the copy number of F.oxysporum and F.moniliform was reduced by 49.91%,65.00%,55.78%,and42.37%,49.35%,41.46%,respectively.In August 2019,the trend of the gene copy number of F.oxysporum and F.moniliform after applying three types of fertilizers was the same as that in2018,and T2 showed better performance.3.In August 2018,through analysis of the soil fungal community structure,it showed that the relative abundance of Fusarium in CK1 and carrier of fertilizer(CK2)was relatively large.At genus level,compared with CK1,the Fusarium relative abundance of T1,T2 and T3 decreased by 63.29%,68.14% and 86.76% respectively.The Penicillium and Trichoderma relative abundance of T1,T2 and T3 increased by 227.18%,222.91%,890.94%,and 76.55%,462.71%,213.56%,respectively.The Ace index,Chao index and Shan index increased significantly,while Simpson index decreased.It indicated that the application of fertilizer could improve the diversity of soil fungi.4.After applying three types of fertilizers,soil enzyme activity could be improved and contents of phlorizin,phloretin,ferulic acid,catechin,vanillin and benzoic acid were reduced.Among them,compared with CK1,the phlorizin and phloretin were reduced by 43.25%,49.28%,49.08% and 44.58%,51.70%,52.69%,respectively.Both CK1 and CK2 had no significant differences in contents of phlorizin,phloretin,ferulic acid,catechin,vanillin and benzoic acid.5.Results in 2018 and 2019 for two consecutive years showed that the application of three fertilizers could increase plant height,ground diameter,fresh weight and dry weight.The biomass of T2 and T3 on biomass increase of Malus hupehensis Rehd.was significant.In August 2018,compared with CK1,the plant height,fresh quality indexes of Malus hupehensis Rehd.increased by 41.87%,48.52%,46.26%,and 44.68%,48.32%,47.66%,respectively.In August 2019,after applying T2,T3 the plant height,ground diameter,and fresh quality indexes of Malus hupehensis Rehd.seedlings increased by 48.80%,44.08%,42.20%,41.27%,and 46.50%,42.68%,respectively.The change trend of indicators in 2018 and 2019 is consistent.6.All three types of fertilizers could promote root growth and increase root respiration rate.In general,the effect of T2 was better.In August 2018,compared with CK1,the root length,surface area and root volume of T1,T2,T3 increased by 56.59%,60.74%,63.14%,39.38%,65.54%,62.61%,and 113.30%,153.76%,154.39%,respectively.The change trend of indicators in 2018 and 2019 is consistent.7.In August 2018,through measuring the photosynthetic parameters of Malus hupehensis Rehd.,it was found that the net photosynthetic rate,transpiration rate and stomatal conductance of Malus hupehensis Rehd.were all improved after applying three types of fertilizers.At the same time,the content of chlorophyll a,chlorophyll b and carotenoid in Malus hupehensis Rehd.could be increased by applying three types of fertilizer.The net photosynthetic rate and transpiration rate of the three fertilizers were increased by 1.34 folds,1.38 folds,1.38 folds,and 1.72 folds,1.90 folds,1.68 folds than CK1,respectively. |
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