Effect Of Humic Acid Compound Fertilizer,Compound Microbial Fertilizer And Paecilomyces Variotii Extract On Pear Trees

Pear is one of the four main fruit tree species in China,with the highest cultivated area and yield in the world.In the cultivation and management of pear trees,the use of fertilizers,pesticides and other inputs often has problems such as excessive use of chemical fertilizers and pesticides,low grade of applied organic fertilizers,and arbitrary ratio of organic and inorganic fertilizers,which leads to the decrease of soil quality and poor quality of pear fruit,affecting the high-quality development of pear industry.Under the background of reducing the application of chemical fertilizers/pesticides and increasing their efficiency,key measures such as replacing chemical fertilizers with organic fertilizers,applying new functional/synergistic fertilizers,and carrying out immune induction have attracted much attention.Therefore,in this study,Huangjinmi pear was used as the experimental material to carry out the experimental research on the optimization of organic and inorganic application,the effect of Paecilomyces variotii extract(PVE)on promoting growth and drought resistance,and the combinatorial optimization of new agricultural inputs.By analyzing the indicators of pear yield,quality and soil properties,the soil quality was comprehensively evaluated,and the best combination formula of experimental products was explored to provide technical support for the high-quality sustainable development of pear industry.The main results are as follows:(1)The experiment of combined application of organic and inorganic fertilizers showed that the treatment of reducing chemical fertilizer by 20%and adding low amount of organic fertilizer significantly increased pear yield(by 12.80%compared to conventional fertilization),reaching up to 1668.44 kg/667 m~2.The accumulation of nitrogen and potassium in pear treated with 40%reduction of chemical fertilizer and high amount of organic fertilizer was the highest,which are significantly higher than those of conventional fertilization.The application of organic fertilizer can alleviate the soil acidification effect caused by chemical fertilizer application.The treatment that 20%reduction of chemical fertilizer and low amount of organic fertilizer can significantly increase soil available phosphorus content and soil sucrase activity.Two organic+inorganic combination fertilization patterns with better comprehensive effects were selected:20%reduction of chemical fertilizer+low amount of organic fertilizer(3000kg/hm~2),and 40%reduction of chemical fertilizer+high amount of organic fertilizer(6000kg/hm~2).(2)The pot experiment of PVE in promoting growth and drought resistance of pear trees showed that the application of PVE in a certain concentration range could promote the growth of pear trees,increase the activity of antioxidant enzymes in leaves,enhance the photosynthetic capacity of pear trees,and raise soil enzyme activities.Under normal water supply conditions,the new shoot growth length,plant height,stem diameter,and root activity of 5 ng/ml PVE treatment were 31.91%,12.05%,3.54%,and 10.94%higher than those of control,respectively,and the corresponding increases under drought conditions were 25.12%,8.87%,12.21%,and16.98%,respectively.Root application of 5 ng/ml PVE significantly enhanced the drought resistance of pear trees,but when its concentration reaching 20 ng/ml,it had not positive but negative effects on the soil microenvironment.Under drought conditions,the growth chacteristics and antioxidant enzyme activities of pear trees,soil enzyme activities,trehalose content in root exudates and microbial community richness treated with 20 ng/ml PVE were all lower than those treated with 5 ng/ml PVE.(3)The experiment of combinatorial optimization of new agricultural inputs showed that the yield of pear treated with humic acid compound fertilizer,compound microbial organic fertilizer and PVE combination(A1B1C1)was the highest(increased by 15.91%).The combinations of humic acid compound fertilizer can improve soil nitrogen availability.The content of total nitrogen,total phosphorus and total potassium in pear fruit treated with three new inputs,namely humic acid compound fertilizer,compound microbial organic fertilizer,and PVE(A1B1C1),increased by 64.52%,45.83%and 34.15%compared to the conventional control treatment(A0B0C0),and the content of soluble solids,soluble protein,and Vc in pear fruit increased by 7.77%,24.00%,and 36.84%,respectively.By establishing a comprehensive evaluation index of soil quality,a combination of inputs with better comprehensive effects was selected,namely humic acid compound fertilizer+compound microbial organic fertilizer+Paecilomyces variotii extract.In summary,humic acid compound fertilizer,compound microbial fertilizer and 5 ng/ml PVE can improve the soil fertility of pear garden,increase the economic yield of pear trees and improve the quality of pear fruits,and the combination of“humic acid compound fertilizer+compound bacterial fertilizer+5 ng/ml Paecilomyces variotii extract”has the best improvement effect,which is recommended to further promote the application in pear cultivation and management.