Effects Of Substitution Of Chemical Fertilizers By Organic Fertilizers On Peach Fruit Quality And Soil In Different Regions

China’s peach tree planting area and its total production rank the first in the world,and China is the largest country in peach tree production.Peach trees play an irreplaceable role in the development of Chinese agricultural economy.Although the peach fruit yield has been increasing in recent years,there are still a lot of problems in peach production,such as excessive application of nitrogen fertilizers and lack of organic fertilizers.Therefore,this caused a series of problems,such as decrease of soil fertility in the orchard,low yield of peach fruit,and difficulty in improving fruit quality.The results showed that the application of organic fertilizers or bio-organic fertilizers could improve soil fertility of orchards and promote growth of peach tree roots.Organic matters in the organic fertilizers could improve microbial activity in the soil,thereby promoting growth of peach tree and further improving yield and quality of fruit.In this study,we took two peach tree species"Yangxiafei" and "Chinese Shoutao" as research objects in two regions(Xinyi,Jiangsu and Feicheng,Shandong),and used organic fertilizers and bio-organic fertilizers to carry out substitution experiments by organic fertilizers instead of different gradients(15%,25%,35%)chemical fertilizers.Effects of partial substitution by organic fertilizers and bio-organic fertilizers on fruit yield and quality were investigated,and the changes in soil physical and chemical properties and soil microbial community structure of peach orchards in the two places were studied.It is expected that key technology of organic substitution for peach trees in different regions will be established.The main findings are as follows:1.After applying organic fertilizers and bio-organic fertilizers to peach orchard in two regions to replace chemical fertilizers,we found that increasing application of organic fertilizers had different effects on yield and fruit quality of peach trees.For "Yangxiafei"peach in Xinyi,Jiangsu province,substitution of chemical fertilizers with organic fertilizers had no significant effect on peach fruit yield,but improved the quality of peach fruit.Treatment that substituted by 25%bio-organic fertilizers significantly reduced the hardness and titratable acid content of peach fruit,and significantly increased the soluble solids in peach fruit.In general,the substitution of 25%chemical fertilizers with bio-organic fertilizers in this area could improve the fruit quality of "Yangxiafei" peach.For the"Chinese Shoutao" peach in Feicheng.Shandong province,substitution of 35%chemical fertilizers by bio-organic fertilizers significantly increased the peach fruit yield and reduced the fruit hardness.The content of soluble sugar,titratable acid content and sugar-acid ratio were significantly increased when bio-organic fertilizers replaced 15%of chemical fertilizers.In general,fruit quality of "Chinese Shoutao" peach could be improved by replacing 15%chemical fertilizers with bio-organic fertilizers in this region.2.The use of organic fertilizers instead of chemical fertilizers in two peach orchards could increase most of the soil nutrients and had significant impacts on content of soil organic matters.Specifically,substitution of different proportions of fertilizers with organic fertilizers in Xinyi,Jiangsu province could significantly increase content of organic matters in soil,but had no significant effect on soil pH.The substitution by bio-organic fertilizers instead of 15%and 25%chemical fertilizers significantly increased the alkali-hydrolyzed nitrogen content.Substitution of bio-organic fertilizers for 35%fertilizers or the substitution of organic fertilizers for 25%fertilizers significantly improved content of available phosphorus in soil.In general,the substitution of organic fertilizers for different proportion of chemical fertilizers could significantly increase content of available potassium in soil in Feicheng Shandong province.The substitution of organic fertilizers instead of 15%chemical fertilizers significantly increased content of organic matters,alkali-hydrolyzed nitrogen and available potassium in soil.The substitution of 15%and 25%fertilizers with bio-organic fertilizers could significantly increase the content of organic matter and alkali-hydrolyzed nitrogen in soil.3.The results of high-throughput sequencing of soil bacteria showed that substitution of chemical fertilizers with organic fertilizers in two peach orchards had no significant effect on bacterial diversity,but could change the structure of soil bacterial community.Relative abundance of Proteobacteria in soil was increased by applying organic fertilizers,and relative abundance of Chloroflexi and Acidobacteria decreased.In addition,the substitution of chemical fertilizers with organic fertilizers in Xinyi area of Jiangsu province reduced relative abundance of bacteria in Gemmatimonadetes and Planctomycetes,and increased relative abundance of Patescibacteria.Relative abundance of Bacteroidetes and Firmicutes was increased by replacing chemical fertilizers with organic fertilizers in Feicheng region,Shandong province.In addition,relative abundance of Gemmatimonadetes decreased after substituted with bio-organic fertilizers.In summary,the application of organic fertilizers and bio-organic fertilizers in substitution of partial chemical fertilizers will not only reduce fruit yield,but also improve fruit quality,increase soil organic matter and available nutrients content,and change soil microbial community structure.Among them,in Xinyi,the substitution of 25%chemical fertilizers with bio-organic fertilizers has the best fruit quality,and the substitution of 35%chemical fertilizers with bio-organic fertilizers has the highest soil nutrient improvement;In Feicheng the substitution of 15%chemical fertilizers with bio-organic fertilizers has the best fruit quality and the substitution of 15%chemical fertilizers with organic fertilizers increases the soil nutrients most.