| From March 2017 to November 2019,pot experiments and field experiments were carried out in the national Apple engineering technology research center of School of horticulture science and engineering of Shandong Agricultural University and fengmaozhai village,Jincheng Town,Laizhou City,Yantai City,Shandong Province.The potted soil was taken from the 25-year-old apple garden in fengmaozhai village,Laizhou City,Shandong Province.Some fields of the garden were tested at the same time.The pot experiment was conducted with Malus hupehensis Rehd.as the test material,and the field experiment was conducted with2-year-old Yanfu 3/T337 as the test material.The effects of the application of quicklime,the mixture of quicklime and superphosphate,and the application of plant ash on soil microbial environment of continuous cropping and replant plant were studied.The main results are as follows:1.Different measures can improve pH value of continuous cropping soil and effectively alleviate soil acidification.Under the condition of potting,the pH value increased by 11.2%,22.3% and 38.0% respectively with the increase of concentration gradient after the application of quicklime;the pH value increased by 6.9%,17.9%and 31.9% with the increase of concentration gradient after the mixture of quicklime and superphosphate;the pH value increased by 6.7%,15.0% and 27.7% with the increase of concentration gradient after the application of plant ash.The results of field experiment were consistent with that of pot experiment.2.The application of quicklime or plant ash and the mixture of quicklime and superphosphate of appropriate concentration in soil can improve the biomass and root index of replanted plants,and the effect of the mixture of 1g/kg quicklime and 1g/kg superphosphate is the best: in the pot experiment,the plant height,ground diameter,fresh weight and dry weight of the aboveground and underground parts of Malus hupehensis Rehd.were increased by 49.9%,80.4%,83.9%,153.8%,114.3% and221.0% respectively compared with the control,and the root length,root surface area,root volume and root tip number were increased by 204.4%,254.2%,354.7% and133.6% respectively compared with the control,in the field experiment,the plant height,ground diameter,shoot amount and shoot length of replant plant increased by37.2%,28.0%,93.9% and 59.0% respectively compared with the control.3.Different treatments had effects on the root respiratory rate and protective enzyme of Malus hupehensis Rehd.Among them,1g/kg quicklime mixed with 1g/kg superphosphate had the best effect,the root respiratory rate was 1.35 times of continuous cropping control,and the activities of SOD,POD and CAT were 1.89 times,2.81 times and 2.36 times of continuous cropping control respectively.The effect of applying 1g/kg quicklime or 2g/kg plant ash was the second,but there was significant difference between them and control.The above three treatments also significantly reduced the content of MDA in roots.4.Pot experiment and field experiment showed that the mixture of 1g/kg quicklime and 1g/kg superphosphate improved the soil microbial environment most obviously,and increased the ratio of bacteria and fungi in the soil to the greatest extent,which was 15.46 times as much as that of continuous cropping control under the condition of pot experiment,in which the number of bacteria and fungi increased by 291.2% and decreased by 74.0% as compared with continuous cropping control;Under field conditions,the number of bacteria increased by 150.0% and193.5% respectively in 2018 and 2019;the number of fungi decreased by 53.2% and54.9% respectively;the ratio of bacteria to fungi was 5.46 times and 6.38 times of continuous cropping control respectively,which was significantly different from other treatments.In addition,the copy number of Fusarium solani and Fusarium oxysporum genes in soil was measured by real-time fluorescence quantitative technology.It was found that the copy number of Fusarium solani and Fusariumoxysporum in pot culture decreased by 70.3% and 57.1% respectively compared with continuous control;The copy numbers of two Fusarium species decreased by 63.4%and 51.5% respectively in 2018,61.4% and 58.3% respectively in 2019,compared with the continuous cropping controlunder field conditions.Other treatments also reduced the copy numbers of two Fusarium species.5.The main soil enzyme activity could be improved by applying the appropriate concentration of quicklime or plant ash,or the mixture of quicklime and superphosphate.Under the condition of pot culture,the application of 1g/kg quicklime significantly increased the urease activity in the soil,which was 2.26 times of that of continuous cropping control.In terms of sucrase,phosphatase and catalase,the mixture of 1g/kg quicklime and 1g/kg superphosphate had the best effect,which were 1.71 times,1.55 times and 1.47 times of that of continuous cropping control respectively.In the field experiment,the soil enzyme activities of different treatments were all increased,and the trend was consistent with that of pot condition. |
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