Influence of plant growth promoting rhizobacteria and hydro-priming on some ‎physiological indices of lemon balm (Melissa officinalis)‎

Application of plant growth promoting rhizobacteria metabolism and metabolic processes to increase plant efficacy. The aim of this study was to investigate the effect of seeds hydropriming and inoculation of plant growth promoting rhizobacteria (Pseudomonas fluoresense, Pseudomonas p < /em>utida) to soil as biological stimulative on some physiological traits of Melissa officinalis. The experiment was conducted as a factorial based on a completely randomized design in greenhouse conditions and laboratory of Medicinal Plants Department of Arak University. The first factor was hydropriming at different times (12, 24, 48 and 72 hours), and the second factor was two bacterial species (Pseudomonas fluoresense, Pseudomonas putida), control (without inoculation). The results showed that seed hydropriming at different times and growth promoters increased the photosynthetic pigments, phenol, flavonoids, percentage and essential oil yield. Also, hydropriming for 48 hours with Pseudomonas putida bacteria resulted in a significant increase in flavonoid content and a significant effect on phenol content during 12 hours with Pseudomonas fluoresensebacteria. According to the positive and additive effects of plant growth promoting rhizobacteria on Melissa officinalis, the plant growth promoting rhizobacteria could be recommended as an alternative to chemical fertilizers to reduce the consumption of chemical fertilizers and guaranty the production of medicinal plants, free of chemicals.