Stimulatory effect of Pseudomonas fluorescens and P. putida bacteria on germination features and growth of lemon balm (Melissa officinalis)

In order to study the effect of seeds priming with growth stimulating bacteria (biopriming) and hydroperiming on germination parameters, an experiment was carried out on a factorial experiment based on randomized complete design with three replications. Experimental treatments consisted of hydropriming at different times (72, 48, 24, 12 h) and biopriming with Pseudomonas fluorescens and P. putida growth stimulating bacteria at different times (72, 48, 24, 12 h) compared to control (without inoculation). The results showed that seed hydropriming at different times had a significant effect at 1% probability level on germination indices, seed vigor, mean radicle and plumule length, percentage and germination rate. Germination and vigor index showed significant difference upon biopriming treatment. The highest germination index was obtained in inoculation with P. putida in 48 h and the lowest seed vigor index was obtained in seed inoculation with P. fluorescens within 72 h. The maximum mean radicle and plumule length were observed upon P. putida (3.30 and 3.67 mm) and P. fluorescens (3.13 and 3.17 mm) inoculation treatments, respectively. Also, biopriming with P. putida had a positive and significant effect on water uptake and alpha-amylase enzyme activity compared to P. fluorescens and hydro-priming under different times. Therefore, in order to improve germination indices and seedling vigour index, biopriming with P. putida bacteria can be recommended.