AgroFossilFree - Soil tillage rather than crop rotation determines assembly of the wheat rhizobacterial communities

Γενική περιγραφή

Root-associated bacterial activity processes are key requirements for agricultural production, yet we have limited understanding about the processes and drivers of rhizobacterial community assembly under typical farming practices. Herein we assessed the rhizobacterial diversity, co-occurrence network connectivity, and assembly processes of dryland wheat rhizobacterial communities and its environmental drivers under a long-term crop rotation (maize-wheat, MW; soybean-wheat, SW) × soil tillage (chisel plow tillage, CPT; zero tillage, ZT; plow tillage, PT) system. The results indicated that crop rotation, soil tillage, and their interactions substantially affected the edaphic properties, where both CPT and ZT increased the levels of soil moisture, pH, organic carbon, and total nitrogen, and SW increased the levels of soil pH and total nitrogen. Compared with MW, SW increased the relative abundance of Proteobacteria (5.82%), while decreased the relative abundances of Firmicutes (22.96%) and Patescibacteria (20.98%). Regardless of crop rotation, there were significant differences in the rhizobacterial community composition among three tillage practices. Rotation × tillage interaction exerted stronger effect on the community composition than their individual contributions. The rhizobacterial network was more densely connected under the SW (edges = 2555, density = 0.122) than that under the MW (edges = 1785, density = 0.082), and the network connectivity showed a decreasing tendency with decreasing tillage intensity. Crop rotation changed the proportions of deterministic and stochastic processes, while soil tillage determined the homogenizing dispersal dominated rhizobacterial community assembly for both MW and SW, due mainly to its significant effects on the soil moisture, total nitrogen, pH, and community diversity. Collectively, these findings provide a theoretical overview of agronomic practice-driven alteration of the rhizobacterial communities, and are expected to provide support for microbiome manipulation and adaptive management toward a more sustainable agriculture under dryland conditions.