Crop development has more influence on shaping rhizobacteria of wheat than tillage practice and crop rotation pattern in an arid agroecosystem

Abstract

Root-associated bacteria are studied under a single agricultural measure, but the responses of rhizosphere bacterial communities toward agricultural management, in an arid agroecosystem, are unclear. Here, we evaluated the effects of tillage practice, crop rotation pattern, and crop development on rhizobacteria in a field experiment in the dryland region of northern China. Three tillage [chisel plow tillage (conservation), zero tillage (conservation), and plow tillage (conventional)] practices and two crop rotation (maize–wheat rotation and soybean–wheat rotation) patterns were been combined to assess changes in rhizosphere bacterial communities during wheat development. Our results showed that conservation tillage practices had considerable effects on soil physicochemical properties compared with conventional tillage, thus changing the rhizosphere microenvironment. Spearman's correlation analysis also indicated that soil physicochemical properties were closely related to the relationships among the rhizosphere bacterial communities and taxa. Furthermore, the composition and α-diversity of the rhizosphere bacterial communities were substantially affected by the crop growth stage and tillage practices; however, the legacy effect of the previous crop had different effects on the rhizosphere bacterial communities owing to the short period of implementing crop rotation. The phylogenetic diversity and taxonomic composition of rhizosphere bacterial communities were mainly explained by the crop growth stage and tillage practice, respectively. Additionally, conservation tillage practices and soybean–wheat rotation pattern both delayed rhizobacteria successions. Co-occurrence networks also showed that the differential modules among the rhizosphere bacterial communities decreased with wheat development, whereas the soybean–wheat rotation pattern increased their degree of co-occurrence. The differences in taxonomic compositions and phylogenetic diversities of the rhizosphere bacterial communities may affect their potential functions and alter crop growth and development.