Rhizobacterial communities and fine root traits together reveal variations in growth performance of Quercus acutissima in different provenances

It is important to understand the variations in intraspecific growth performance for forest management. We evaluated the relationships among fine root traits, rhizobacterial community structure, and growth variables in different oak (Quercus acutissima) provenances. Four oak provenances with different growth performances were studied. In each provenance, growth variables, fine root traits, rhizosphere soil chemical properties, and rhizobacterial abundance were measured. The structure of rhizobacterial communities was assessed by 16S rRNA gene sequencing. The co-occurrence patterns of bacterial taxa were analyzed by network analysis. The relative contribution of fine root traits and rhizobacterial communities to variations in growth performance was evaluated by hierarchical partitioning analysis. Growth performance of the four oak provenances was positively correlated with the specific root length. The β-diversity of rhizobacterial communities, but not α-diversity, was positively correlated with the growth variables. The relative abundance of Actinobacteria (e.g., Actinospica and Conexibacter genera) increased with aboveground biomass. The co-occurrence network analysis showed more clusters with highly interconnected taxa in the high-yielding provenances. Variation in growth performance of oak in different provenances was significantly affected by the rhizobacterial community structure and fine root traits, with the former being a more prominent factor.