Effects Of Selenium-Tolerant Bacteria And AM Microbial Agent On Selenium Uptake And Soil Selenium Availability Of Pakchoi In Selenium-Enriched Lateritic Red Soil

Guangxi is a selenium-rich province,which has the largest area of selenium-rich soil in the country.However,the selenium-rich soil can not grow selenium-rich crops.This study used selenium-rich lateritic red soil,AM bacteria,and selenium-tolerant bacteria as experimental materials to explore the effects of AM agents and selenium-tolerant bacteria on soil Se availability.Further,the effect mechanism of AM agents and selenium-tolerant bacteria on Se uptake of pakchoi was explored through pot experiments.The results can provide a theoretical and technological innovation basis for the sustainable development of the selenium-rich agricultural products industry and the development of selenium-rich microbial fertilizers.The main findings are as follows:（1）Both AM bacteria agent and selenium-tolerant bacteria could increase the content of available Se in soil.After adding selenium-tolerant bacteria and AM bacteria,the content of available Se in the simulation experiment increased by 42.22%～141.85%,and the available Se in pot experiment increased by 153.84%～205.14%;（2）AM bacteria agent and selenium-tolerant bacteria can change the content of Se in soil.After adding selenium-tolerant bacteria and AM bacteria,compared with the control treatment,the Soluble Se in simulated soil increased by 3.50～13.90μg·kg^-1,the Exchangeable Se increased by22.73～62.71μg·kg^-1.However,the Iron-manganese oxide-bound Se decreased by 3.27～20.90μg·kg^-1,the Organic binding Se decreased by20.38～56.67μg·kg^-1.There is no change of the Residual Se.The soluble Se and exchangeable Se in the pot experiment increased by 10.22～19.8μg·kg-1 and 38.36～57.13μg·kg^-1.Meanwhile,the Iron-manganese oxide-bound Se,the Organic binding Se,and the Residual selenium decreased by 8～11.91μg·kg^-1,31.66～60.04μg·kg^-1,and 3.36～5.55μg·kg^-1,respectively.（3）AM bacteria agent and selenium-tolerant bacteria could significantly promote the absorption of selenium by pakchoi in soil.After adding AM and selenium-tolerant bacteria,the aboveground and underground selenium content of pakchoi increased to 34.23～59.24μg·kg^-1and 52.91～77.87μg·kg^-1.The enrichment coefficient and transport coefficient were as high as 0.067 and 0.88,respectively.（4）AM bacterial agent and selenium-tolerant bacteria could significantly change the enzyme activity of potted soil.The activity of soil protease and soil catalase increased by 4.46～16.43 times,and 1.26times,respectively.The Soluble Se and The Exchangeable Se content were positively correlated with soil protease and soil catalase activity,but the Iron-manganese oxide-bound Se and the Organic binding Se were on the contrary.The contents of soluble Se and exchangeable Se in soil were positively correlated with soil protease and soil catalase activity.All the above results showed that selenium-tolerant bacteria and AM bacterial agents could increase the activities of soil acid phosphatase,soil protease,and soil catalase.Further,they can significantly increase the content of available selenium,soluble selenium,and exchangeable selenium in the soil.Finally,they can enhance the selenium absorption of pakchoi,thus increasing the selenium content of pakchoi.