Optimal Management Of Citrus Nutrients In Facilities In Chongming District And Research On Orchard Grass

The healthy and sustainable development of Chongming citrus industry is of great significance to the increase of local farmers’production and income.The daily management of citrus orchards in this region is still relatively extensive,and the fertilization is mainly balanced fertilizer and ignores the input of organic fertilizer and medium and trace elements,which restricts the green transformation and upgrading of the local citrus industry.In recent years,Hongmeiren citrus has gradually become the main cultivars of Chongming citrus industry,but due to the high salt content of Chongming soil parent material,long-term facility cultivation will intensify soil salt accumulation.Therefore,how to provide a scientific orchard management scheme for Hongmeiren cultivation to alleviate soil salinity stress is the goal of this study.In this thesis,Chongming Hongmeiren was the main research object,and organic fertilizers to alleviate the risk of salt accumulation were selected through indoor soil culture experiments and used in orchard experiments to explore the response of fruit yield and quality to optimize fertilization and orchard grass measures,in order to provide scientific basis for improving the quality and efficiency of Hongmeiren.The main findings are as follows:（1）Three kinds of organic fertilizer:salt content:chicken manure>cow manure>vermicompost.The application of vermicompost to citrus orchards at Chongming facilities has no risk of soil salt accumulation;It is necessary to strictly control the input of chicken manure,because its salt content exceeds the standard（especially Na⁺ions）;Although cow manure can lead to an increase in Ca²⁺ions in the soil,proper control of the dosage can also be applied to citrus production.（2）The total nitrogen content of soil with the addition of nitrification inhibitors（OPT+NI）was significantly higher than that of conventional treatment（FP）in July,and it can be assumed that the application of nitrification inhibitors can reduce soil nitrogen loss.The addition of vermicompost with low salinity（FP+O）to the FP treatment had no significant effect on the spring shoot number,tip length,tip thickness and leaf SPAD value of Red Beauty,but the optimized treatment（OPT,citrus special fertilizer+vermicompost）significantly improved tree growth and development,and the spring tip length increased by26.8-40.1%compared with FP.In addition,optimized fertilization had a significant effect on fruit quality,and OPT significantly improved fruit reducing sugars（23.3%）,VC（34.6%）,soluble solids（12.7%）and solid-acid ratio（32.4%）compared with FP treatment.（3）Orchard grass helps to improve soil organic matter,promote the growth and development of fruit trees,and improve fruit quality.Compared with the routine management（FP）of farmers,the soil organic matter treated with alfalfa（FP+AL）and alfalfa（FP+LU）increased by 13.4%and 4.9%,respectively.The soil organic matter of optimized fertilization combined with orchard grass treatment（OPT+AL and OPT+LU）increased by 9.5%and 5%,respectively,compared with OPT treatment.Compared with ploughing,the growth and development of fruit trees treated with grass treatment were improved to different degrees.Compared with FP+AL,the content of reducing sugar,VC,soluble solids and solid-acid ratio increased by 5.8%,2.4%,3.7%and 18.2%,respectively,and the reducing sugars of OPT+AL-treated fruits increased by 7.1%compared with OPT.