Effects of PGPR on Arsenic Accumulation and Physiological Characteristics of Aquatic Plants under Arsenic Stress
To investigate the enrichment and physiological response of arsenic(As)in heavy metal polluted water by a combination of aquatic plants such as Phragmites australis,Juncus effusus,and root growth-promoting bacteria(PGPR),a total of 24 treatments were simulated with water arsenic concentrations(0,5,15,30 mg/L)and PGPR strains of Pseudomonas fluorescens(Pf),Bacillus velezensis(Bv),and no strain(control,CK)added.The results showed that low concentrations of arsenic had a promoting effect on the growth of P.australis and J.effusus,while high concentrations inhibited it.Adding PGPR could increase the height and biomass of P.australis and J.effusus,increased chlorophyll content and chlorophyll fluorescence parameters,improved the root configuration and vitality of P.australis and J.effusus,increased nitrogen absorption by plant aboveground and root systems,and enhanced the ability of root systems to accumulate arsenic.At the arsenic concentration of 5 mg/L,compared with CK,the height,biomass,root nitrogen uptake,and aboveground nitrogen uptake of P.australis treated with Pf increased by 54.6%,38.5%,11.5%,and 48.4%,respectively.The total chlorophyll content increased by 23.4%,and the maximum photochemical efficiency(Fv/Fm)and potential activity(Fv/Fo)of PSⅡincreased by 6.7%and 20.6%,respectively.The total length,total projected area,total volume,and root tips number of roots increased by 4.8%,19.3%,27.4%and 14.8%respectively.The height,biomass,root nitrogen uptake,total chlorophyll content,chlorophyll fluorescence parameters,and root configuration parameters of P.australis treated with Bv also showed varying degrees of improvement.At the arsenic concentration of 5 mg/L,compared with CK,the height,biomass,chlorophyll content,chlorophyll fluorescence parameters,and root system configuration of J.effusus treated with Pf and Bv addition were also improved.At the arsenic concentration of 30 mg/L,the arsenic content in the aboveground and root parts of P.australis treated with Pf reached its maximum value,up to 126.1 and 432.1 mg/kg,respectively.The conclusion is that P.australis+Pf has the best absorption and enrichment effect on arsenic,and could be applied to the ecological restoration of heavy metal arsenic polluted water bodies.
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