Soil Bacterial Communities Across Seven Rhizoma Peanut Cultivars (Arachis glabrata Benth.) Respond to Seasonal Variation.

Abstract

Soil microorganisms play key roles in soil nutrient transformations and have a notable effect on plant growth and health. Different plant genotypes can shape soil microbial patterns via the secretion of root exudates and volatiles, but it is uncertain how a difference in soil microorganisms induced by crop cultivars will respond to short-term seasonal variations. A field experiment was conducted to assess the changes in soil bacterial communities of seven rhizoma peanut (Arachis glabrata Benth, RP) cultivars across two growing seasons, April (Spring season) and October (Fall season). Soils' bacterial communities were targeted using 16S rRNA gene amplicon sequencing. Bacterial community diversity and taxonomic composition among rhizoma peanut cultivars were significantly affected by seasons, cultivars, and their interactions (p < 0.05). Alpha diversity, as estimated by the OTU richness and Simpson index, was around onefold decrease in October than in April across most of the RP cultivars, while the soils from Arblick and Latitude had around one time higher alpha diversity in both seasons compared with other cultivars. Beta diversity differed significantly in April (R = 0.073, p < 0.01) and October (R = 0.084, p < 0.01) across seven cultivars. Bacterial dominant taxa (at phylum and genus level) were strongly affected by seasons and varied towards more dominant groups that have functional potentials involved in nutrient cycling from April to October. A large shift in water availability induced by season variations in addition to host cultivar's effects can explain the observed patterns in diversity, composition, and co-occurrence of bacterial taxa. Overall, our results demonstrate an overriding effect of short-term seasonal variations on soil bacterial communities associated with different crop cultivars. The findings suggest that season-induced shifts in environmental conditions could exert stronger impacts on soil microorganisms than the finer-scale rhizosphere effect from crop cultivars, and consequently influence largely microbe-mediated soil processes and crop health in agricultural ecosystems.