Effects of Submerged Stress on Inter-root Soil Nitrogen Transformation of Vetiveria zizanoides and Structural Diversity of Bacterial Communities

WEI Jiating; HU Tian; ZHAO Ruibo; LIU Ying; JI Mingfei; ZHANG Jun

doi:10.15933/j.cnki.1004-3268.2025.04.008

Abstract：In order to study the effect of inter-root bacterial community diversity on soil nitrogen transformation in the vegetation of Danjiangkou Reservoir fallout zone,Vetiveria zizanoides was selected as experimental material,and control(CK),semi-submerged and fully submerged groups were set up to systematically study the effect of submerged stress on inter-root nitrogen transformation and bacterial community through soil physicochemical analyses,enzyme activity determination combined with high-throughput sequencing of 16S rRNA and function prediction of PICRUSt2.The results showed that the content of inter-root soil ammonium nitrogen(NH4+-N)was significantly elevated under submerged stress,and the content of nitrate nitrogen(NO3--N)and nitrite nitrogen(NO2--N)were significantly reduced by 66.83%—74.27%and 36.84%—42.11%,respectively,compared with CK.Compared with CK,soil hydroxylamine reductase(HR)activity in the fully submerged group was significantly reduced by 34.48%,and nitrate reductase(NR)and nitrite reductase(NiR)activities were significantly increased.The results of Alpha diversity analysis showed that flooding stress significantly increased the diversity of inter-root bacterial communities,and the order was fully submerged group>semi-submerged group>CK.The non-metric multidimensional scaling analysis and principal component analysis showed that the bacterial community structure showed gradient differences with the increase of submerged depth.Community structure analysis showed that the relative abundance of Firmicutes in the semi-submerged and fully submerged groups increased significantly by 45.14%and 87.99%,respectively,while the relative abundance of Cyanobacteria in the fully submerged group decreased significantly by 84.98%.Functional prediction revealed that the abundance of genes for the key enzymes of biological nitrogen fixation pathway(Nitrogenase 1.18.6.1)was significantly increased by 198.43%to 198.97%under submerged stress,but it suppressed the abundance of genes for nitrous oxide reductase(1.7.2.4).Redundancy analysis indicated that soil NO3--N and NR activities were the main factors affecting the soil bacterial community.In conclusion,submerged stress affects the nitrogen transformation process in inter-root soils and alters bacterial community structure,which may lead to ecological risks of N2O greenhouse gas accumulation.