Screening and identification of a fungus Fusarium redolens and its effect of selenium uptake and cadmium reduction on Cardamine violifolia
One functional fungus strain was isolated and screened from plant rhizosphere soil with high background value of 50.187 mg/kg selenium(Se)and 50.311 mg/kg cadmium(Cd)using selective cul-ture medium to solve the problem of co-accumulation of selenium and cadmium in crops.The fungus strain obtained was identified as Fusarium redolens.The changes in available selenium and cadmium in soil,as well as the content of Se and Cd in edible parts of plants were determined with soil simulation experiments and pot experiments.Evaluate The effects of fungus on selenium uptake and cadmium reduction based on the enrichment of selenium/cadmium and the transport coefficients.The results of soil simulation experi-ments showed that the rate of active selenium was positively correlated with culture time after the fungus was inoculated,while the rate of cadmium immobilization was opposite.The rate of active selenium reached its peak on the 5th day,at 60.9%.The rate of cadmium immobilization was highest at 41.2%on the third day and lowest at 27.3%on the fifth day.The results of the pot experiments showed that adding 108 cfu/mL of fungi significantly reduced the soil pH by 0.35 units compared to the control.There was no adverse effect on the growth of the seedlings of Cardamine violifolia,with an average plant height,root length,and biomass of 7.4 cm,9.6 cm,and 2.9 g,respectively,all higher than that of the control.The content of avail-able selenium in the soil significantly increased,with the highest rate of active selenium reaching 24.8%,while the content of available cadmium significantly decreased,with the rate of cadmium immobilization of 24.7%.The content of total selenium in the above ground and underground parts of Cardamine violifolia in-creased by 25.6%and 36.8%,respectively,while the content of total cadmium in the above ground and un-derground parts of Cardamine violifolia decreased by 32.7%and 11.6%,respectively.It is indicated that fungi have the ability to activate selenium and immobilize cadmium in natural soil with high background val-ue of selenium and cadmium,and the best effect is achieved when adding a concentration of 108 cfu/mL,which helps to enrich selenium and reduce cadmium in Cardamine violifolia.
selenium(Se)selenium-cadmium concomitantCardamine violifoliafungusbioavail-ability of selenium and cadmium in soil
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