The persistence and performance of phosphate-solubilizing qzr14 in a cucumber soil.

The persistence and performance of plant growth-promoting microorganisms (PGPMs) in soil are considered critical features for effectiveness, yet they are poorly understood. Here, we investigated the colonization and activity of a new PGPM, phosphate-solubilizing qzr14, in a pot culture experiment using cucumber as test crop for 20 days. The number of and bacterial diversity in the rhizosphere and bulk soil were monitored by real-time PCR and DGGE, respectively. Soil phosphorus and cucumber biomass were also examined. qzr14 effectively colonized the rhizosphere soil (bacterial density ranging from 2.70 × 10 to 1.18 × 10 copies per gram dry soil). qzr14 inoculation had significantly positive effects on bacterial diversity (BD) of the rhizosphere and bulk soil and the ratio of soluble phosphorus to total phosphorus (SP/TP). The number of in the rhizosphere soil was significantly related to SP/TP and the BD of the rhizosphere and bulk soil. BD in rhizosphere soil was significantly related to SP/TP and BD in bulk soil. Based on the results of correlation analysis, we inferred that the introduced qzr14 effectively colonized the rhizosphere of cucumber, and then expanded its bacterial community by solubilizing soil phosphorus. The expanded bacterial communities might promote cucumber growth by some new functions.