Effects Of Long-Term Sod Culture On Rhizosphere Microecology Of Loquat Orchard In Red Soil Slope

Sod culture is an important way to promote the sustainable and high-quality development of the ecological fruit industry.Scientific and reasonable sod culture can regulate the coordinated development of various components of the rhizosphere microecology of fruit trees,create a good rhizosphere nutrient environment,and thus achieve good growth of fruit trees and improvement of fruit quality.However,there have been relatively few studies on the impacts of long-term sod culture on the rhizosphere microecology of fruit trees in the past.Therefore,this study used a long-term positioning experiment of 22 years of sod culture in a sloping loquat orchard within the Jinshan Soil and Water Conservation Science and Education Park of Fujian Agriculture and Forestry University as the experimental site.Two different sod culture treatments(Covering the whole orchard and Strip covering)were selected,and tillage was used as the control to study the effects of long-term sod culture on the physicochemical properties,microbial community structure and functional characteristics,enzyme activity,and fruit quality of the rhizosphere soil in the sloping loquat orchard,as well as their interrelationships.The main research conclusions are as follows:1.Long term sod culture in orchards significantly changed the bacterial abundance,community composition,and diversity of rhizosphere soil.Compared with the cleaning tillage,the bacterial abundance index(ACE and Chao1)and diversity index(Shannon)of the soil on the upper slope with two sod culture treatments significantly increased;Compared with the way of covering the whole orchard,strip covering had a more significant effect on improving the soil bacterial abundance index(ACE)and diversity index(Shannon)on the upper slope.Both sod culture treatments significantly increased the relative abundance of Proteobacteria and Myxococcota,the dominant bacteria in the upper slope soil.The increase of the abundance of Nitrosation,Ellin6067 and Haliangium,the dominant bacteria,was conducive to promoting the degradation of soil organic matter and accelerating the cycle of nitrogen and other nutrient elements in the soil ecosystem.The FAPROTAX database was used to predict the process of carbon nitrogen cycle of the orchard soil bacterial community.The results showed that the way of covering the whole orchard significantly increased the abundance of denitrification,nitrite respiration and nitrogen respiration bacteria in the uphill soil,so as to promote nitrogen metabolism in the upper slope soil.2.Long term sod culture in orchards significantly changed the abundance,community composition,and diversity of rhizosphere soil fungi.Compared with cleaning tillage,the fungal abundance index(ACE and Chao1)and diversity index(Shannon)of the soil on the upper slope of the orchard with two sod culture treatments significantly increased;Compared with the way of covering the whole orchard,the strip covering also increased the fungal abundance index(ACE and Chao1)of the downhill soil.Compared with control,both sod culture treatments significantly reduced the relative abundance of pathological fungal species Cylindrocladiella,which to some extent reduced the risk of disease in loquat fruit tree;In addition,strip covering significantly increased the relative abundance of saprophytic fungi and symbiotic fungi in the upper slope soil,among which the abundance of beneficial genera Mortierella,Acremonium and Chaetomium significantly increased,which was conducive to the decomposition of soil organic matter,driving the circulation of soil effective nutrients.3.The content of soil organic matter and available potassium were significantly increased under the Long-term sod culture.Compared with the cleaning tillage,the content of organic matter in the upper slope soil was significantly increased by 27.65% and 85.49%,while the organic matter content in the lower slope soil was significantly increased by26.29% and 24.26%,respectively.The content of available potassium in the upper slope soil was significantly increased by 96.95% and 67.02%,and the content of available potassium in the lower slope soil was significantly increased by 36.09% and 58.21%,respectively;In addition,the content of total nitrogen in the lower slope under strip covering was significantly increased by 255.56% and 166.67% compared with the cleaning tillage and covering the whole orchard,respectively,4.The correlation analysis between soil physicochemical properties and dominant soil microorganisms shows that the content of organic matter,alkali hydrolyzed nitrogen,total phosphorus,available phosphorus,and available potassium are important factors affecting the composition of soil bacterial community structure;p H value,organic matter,available potassium,and total nitrogen content are important factors affecting the composition of soil fungal community structure5.The results of soil enzyme analysis showed that among the three treatments,the acid phosphatase activity in the upper slope under the way of covering the whole orchard was significantly increased,while the acid phosphatase activity in the lower slope under the strip covering was significantly increased;There was no significant difference in soil sucrase activity under different sod culture treatments,as the enzyme activity in the lower slope was significantly higher than that in the upper.6.There were significant differences in the effects of three treatments on single fruit weight,vitamin C content,soluble sugar,and total acidity.Among them,strip covering significantly increased the soluble sugar content of the fruit and reduced the total acidity of the fruit,which promoted the accumulation of sugar in the fruit and converted fruit acid to fructose.As mentioned in the review,implementing long-term sod management in sloping orchards can effectively improve soil organic matter,total nitrogen and available potassium nutrients content,alleviate nutrient loss,increase the abundance and types of beneficial microorganisms in the rhizosphere soil,reduce the abundance of potential pathogenic bacteria,thereby improving the rhizosphere soil microecological environment,and creating conditions for the healthy growth of fruit trees and the improvement of fruit quality.The strip covering had more significant effects on improving soil nutrient contents and increasing beneficial microbial abundance and species,which created a more suitable rhizosphere microecological environment,improved the fruit quality of loquat to some extent.