Rhizosphere bacterial community structure of three minor grain crops: A case‐study from paired field sites in northern China

Abstract

AbstractRhizosphere bacteria are critical to plant health and ecological functioning. However, our understanding of rhizosphere bacterial community turnover and co‐occurrences with minor grain crops remains limited, especially at regional scales. Herein, we compared the turnover and networks of foxtail millet, proso millet, and sorghum rhizosphere bacterial communities across nine paired fields in northern China. Remarkable differences in community composition, diversity between three minor grain crops, and the influence of region on these indicators was greater than that of crop type. Community richness of foxtial millet, proso millet, and sorgum showed a unimodal curve with latitude increased. Compared to spatial factors, environmental variables had greater effects on the rhizosphere bacterial community turnover in three minor grain crops. Edaphic variables were more important than climatic variables for rhizosphere bacterial community composition in foxtail millet fields. In addition, soil organic matter (OM) and total nitrogen (TN) were the key factors influencing the turnover of rhizosphere communities in foxtail millet and sorghum. In contrast, pH and TN were important factors influencing the turnover of rhizosphere communities in proso millet. Rhizosphere bacterial networks were more closely interconnected in proso millet fields than in the other two crops, showing the lower average path length and diameter, greater average clustering, and graph density. In addition, Proteobacteria, Actinobacteria, and Acidobacteria played major roles in the rhizosphere bacterial network structures and were predicted to maintain generalist metabolic diversity. These findings provide new insights for expanding our knowledge of the biogeography and coexistence theory of minor grain crop ecosystems at a large scale.