Impact Of Reclaimed Water-Cd On Soil Enzymes And Microbial Community In Vegetable Rhizospheres

Reclaimed water and Cd had different effects on soil environment.Soil enzymes,microbial communities and soil physicochemical factors of Chinese cabbage,Radish and Pepper were studied by four treatments,including clear water,clean water Cd,reclaimed water and reclaimed water Cd.To explore how reclaimed water and Cd affect the soil microbial communities in the rhizosphere of the above three vegetables,and to provide a theoretical basis for the soil environment of the vegetable rhizosphere treated with reclaimed water and Cd.Based on the above studies,the following conclusions are drawn:(1)The results of urease and sucrase in the rhizosphere soil of Chinese cabbage and Radish are consistent,they are the middle period of irrigation > the period of harvest > the period of irrigation before irrigation.The three kinds of soil enzyme activities in the rhizosphere soil of Pepper were as follows:harvest period > middle irrigation period > early irrigation period.The activities of urease were Cd > clear water > reclaimed water Cd;sucrase activity was reclaimed water > clear water > regenerated water Cd >clear water Cd;alkaline phosphatase activity in rhizosphere soil of pepper showed as follows: harvest The activity of enzymes in the rhizosphere soil of pakchoi and radish was significantly higher than that in the middle irrigation period and early irrigation stage(P<0.05),but the enzyme activity did not change significantly from the middle irrigation period to the harvest stage in Chinese cabbage and Radish rhizosphere soil.(2)The effects of reclaimed water and heavy metal Cd on soil microbial communities were as follows:The results of Chinese cabbage and Radish were similar,and the results of Pepper were opposite.Reclaimed water irrigation could increase the content of phospholipid fatty acid and decrease the species of microorganism in the rhizosphere soil of Chinese cabbage and Radish,but the content of PLFA in the rhizosphere soil of Pepper decreased and the species increased.Cd decreased the content of PLFA and increased the number of species in the rhizosphere soil of Chinese cabbage and Radish,but increased the content of PLFA and reduced the number of species in the rhizosphere soil of Pepper.Rhizosphere soil microbial Community between Cabbage,Radish and Pepper The soil microbial community structure of Chinese cabbage and Pepper rhizosphere was most affected by reclaimed water irrigation.(3)Soil physicochemical properties analysis showed that reclaimed water irrigation could increase the contents of nitrate nitrogen and available potassium in rhizosphere soil of Chinese cabbage,alkali-hydrolyzed nitrogen and TP in rhizosphere soil of Radish and alkali-hydrolyzed nitrogen in rhizosphere soil of Pepper.The contents of nitrate nitrogen and TN also increased,but decreased the content of TN in Radish rhizosphere soil.The reclaimed water irrigation contributed to the absorption of nitrogen in Radish soil.Cd inhibited the absorption of organic matter and TN in the rhizosphere of Chinese cabbage,but promoted the root of Radish and Pepper.The absorption of organic matter,nitrate nitrogen and available phosphorus in soil.(4)In the treatment of recycled water,P element in soil can promote the activity of urease and phosphatase in rhizosphere soil of Chinese cabbage,and the relationship between reclaimed water and Cd in rhizosphere soil of turnip significantly affected the relationship between physical and chemical properties and enzyme activity.P element in vegetable rhizosphere soil can promote the increase of PLFA content of various microbial groups.The N element can inhibit the content of fungi and K element in soil can promote the increase of total PLFAG and actinomycetes content in the rhizosphere soil of Pepper.