Biopriming of Salvia officinalis Seed with Growth Promoting Rhizobacteria Affects Invigoration and Germination Indices

Plant growth promoting rhizobacteria (PGPRs) are a group of bacteria that can actively colonize plant roots and can modulate plant growth. The present study was aimed to investigate the effects of three PGPRs strains designated as Pseudomonas fluorescens (PF23) and P. putida (PP-41 and PP-159) on seed germination features including germination percentage (GP), mean time germination (MTG), germination rate (GR), root and shoot length and seedling vigor index (VI) of Salvia officinalis L. The bacterial suspension (10 CFU/ml) was used to inoculate the seeds under aseptic conditions. Results revealed that seed treatment of S. officinalis with rhizobacteria including PF-23, PP-41and PP-159 affects differently germination parameters. The maximum (78.5%) and minimum (16.75%) final GP were recorded in PP-41 and PF-23 treatment, respectively. Also, the highest GR, root and shoot length, seedling VI and the lowest MTG were recorded in seeds treated with PP-41, a strain with ability to produce moderate auxin, when compared to the other treatments. It is concluded that net effect of plant–rhizobacteria interactions on seed germination behaviors could be positive, neutral or negative. On the other hand, different strains of rhizobacteria had variable effects i.e., positive, negative and inconsequential effects of PGPRs application were observed on seed germination, root elongation and subsequently seedling VI. As a conclusion, the role of biopriming with PGPRs on germination characteristics and seedling growth varied with bacteria strains.