Effects Of Ozone Stress On Soil Nutrients,Enzyme Activities And Microbial Communities In Soybean Root Soil

Ozone is one of the major atmospheric pollutants,and has a strong damage to crops.The influence of ozone on the upper part of the plant indirectly affects the plant's underground ecological process,and then affects the structure and function of soil microbial community,the activity of soil enzyme and the transformation of soil nutrients,and the change of soil ecological process will in turn affect the plant growth.Therefore,the change of soil microorganism may affect soil nutrient content and soil enzyme activity.In this paper,Open-top chambers?OTCs?were utilized to understand the effect of ozone stress on soybean root soil nutrients,soil enzymes,and soil microbial community structure and function,and to explore the impact of these changes on soybean root growth in different organs of soybean?Glycine max.?under different O₃ concentration at?80±10nL/L and 110±10 nL/L?.Samples were taken at branching,flowering,and podding stages of soybean.The results showed that:?1?Ozone stress can directly affect the soil nutrient content,and change the soil ecological-stoichiometric ratio,then affect the soil nutrient balance.Compared with T1treatment,T2 treatment has a greater impact on soil nutrient elements.In addition,the high concentration of ozone significantly reduced soil C:P and N:P during podding and significantly increased soil C:N during branching.?2?With the prolonged fumigation,soil urease,phosphatase,invertase,amylase and catalase activities decreased significantly under the ozone stress,but the activity of soil polyphenol oxidase increased significantly,which may be related to the increase of soil phenolic acids.?3?Under the ozone stress,the AWCD value increased in branching and flowering stages,and the AWCD value of the podding period decreased;the Shannon diversity index and the Shannon evenness index decreased significantly at each period,and had no significant influence on the Simpson dominance index,and the McIntosh index increased significantly at the branching and flowering stages,while decreased significantly in the podding period.The total PLFAs,PLFAs,PLFAs,actinomycete PLFAs and mycorrhizal fungi PLFAs were significantly lower in the branching stage and pods stage than in the control.The G+/G-in each period were significantly higher than those in the control,and the bacteria/fungi were significantly higher than those in the control.?4?In addition,the results of redundant analysis showed that the soil microbial community had more significant influence on root growth compared with soil physicochemical properties and soil enzyme activity under the condition of high concentration of ozone stress for a long time.Ozone stress can directly affect soil nutrients,change the proportion of different soil elements,affect the activity of soil enzymes,affect the transformation of soil mineral elements,and thus change the soil nutrient cycling.Moreover,ozone stress had negative effects on the root microorganism of soybean,and significantly affected the composition and function of soil microbial community.In addition,changes in soil nutrients,enzyme activities and microbial communities will affect the growth of soybean roots.