Influence of functionalized graphene on the bacterial and fungal diversity of Vicia faba rhizosphere soil

In this study, we aimed to investigate the effect of functionalized graphene on the growth and development of Vicia faba L. by analyzing its impact on the microbial community composition and diversity of rhizosphere peat soil in V. faba plants. Seedlings of V. faba planted in peat soil were treated with either distilled water (CK) or 25 mg·L⁻¹ (G25) of functionalized graphene solution. Results showed that the height and root length of V. faba seedlings in G25 group were significantly higher than those in CK group. Moreover, the total nitrogen and total potassium content of V. faba rhizosphere peat soil in G25 group decreased significantly, while the total phosphorus content increased by 1.27 times compared to the CK group. The microbial community was analyzed by amplifying and sequencing the 16S rRNA gene V3–V4 region of bacteria and ITS region of fungi in rhizosphere soil using Illumina MiSeq technology. Alpha and beta diversity analysis indicated that functionalized graphene increased the richness and diversity of bacteria and fungi in V. faba rhizosphere peat soil. Furthermore, the abundance of three nitrogen cycling-related bacteria, Hydrogenophaga, Sphingomonas and Nitrosomonadaceae, was altered after functionalized graphene treatment. The relative abundance of Basilicum, related to soil phosphorus solubilization, decreased in the fungal community, while the relative abundance of Clonostachys and Dimorphospora, which exhibited strong biological control ability against numerous fungal plant pathogens, nematodes and insect, increased in the soil after functionalized graphene treatment. Redundancy analysis revealed that pH value, organic matter (OM) and total phosphorus (TP) contributed the most to the changes in bacterial and fungal community composition in rhizosphere soil. Overall, our findings suggested that functionalized graphene addition altered the relative abundance of nitrogen and phosphorus cycling-related microorganism in peat soil, promoting changes in the physicochemical properties of the soil and ultimately leading to improved growth of V. faba plants.