纳米碳对水稻根际镉形态及微生物群落结构的影响OA

To investigate the mechanism by which nanocarbon affects cadmium uptake in rice and the structure of rhizosphere soil microbial communities,the rice cultivar'Nipponbare'was used as the test material.Six pot treatments were established:control(CK),carboxylated single-walled carbon nanotubes(TSW),carboxylated multi-walled carbon nanotubes(TMW),cadmium treatment(TCd),cadmium combined with carboxylated single-walled carbon nanotubes(TCd+SW),and cadmium combined with carboxylated multi-walled carbon nanotubes(TCd+MW).The cadmium content in rice tissues,the concentrations of different cadmium fractions in rhizosphere soil,and the structures of bacterial and fungal communities in the rhizosphere soil were determined.The results showed that compared with the TCd treatment,both the TCd+SW and TCd+MW treatments significantly increased cadmium accumulation in rice.Specifically,the TCd+SW treatment increased cadmium contents in roots,stems,and leaves by 114.19%,65.84%,and 195.04%,respectively;the TCd+MW treatment increased these values by 231.46%,205.59%,and 509.17%,respectively.Analysis of cadmium fractions in rhizosphere soil revealed that the exchangeable cadmium content under the TCd+SW treatment was 16.80%higher than that under the TCd treatment.Under the TCd+MW treatment,total cadmium and exchangeable cadmium contents were increased by 9.63%and 45.73%,respectively,compared with the TCd treatment.Microbial community analysis indicated no significant difference in soil bacterial α-diversity between the TCd treatment and CK,whereas the TCd treatment significantly enhanced fungal α-diversity.Compared with the TCd treatment,the TCd+MW treatment significantly reduced both bacterial and fungal α-diversity,significantly decreased the abundance of the plant-growth-promoting bacterium Pseudomonas,and concurrently increased the abundance of the cadmium-activating phylum Actinobacteria and the heavy-metal-tolerant fungal phylum Ascomycota.The TCd+SW treatment only significantly reduced bacterial α-diversity and decreased the abundances of Myxococcota and Cyanobacteria.The study found that soil exchangeable cadmium was the primary factor driving changes in the rhizosphere soil microbial community structure.In summary,carboxylated multi-walled carbon nanotubes can promote cadmium uptake and accumulation in rice by increasing the exchangeable cadmium content in rhizosphere soil,while also altering the rhizosphere soil microbial community structure toward a direction that exacerbates cadmium toxicity.In contrast,carboxylated single-walled carbon nanotubes exert relatively weaker effects on cadmium uptake in rice and the structure of the rhizosphere microbial community.