Improvement of salinity stress in cumin (Cuminum cyminum) seedling by inoculation with Rhizobacteria

Cumin (Cuminum cyminum L.) is the second most popular spice in the world, after black pepper, which is sensitive to salinity. In order to investigate the effect of seed bio-inoculation with plant growth promoting Rhizobacteria on germination and seedling indices of cumin under salinity stress, an experiment was laid out based on a completely randomized design with two factors and four replications in 2017 at Seed Science and Technology Laboratory, Yasouj University, Iran. Experimental factors included bio-inoculation with 3 strains, viz. PF2, PF25, and CHA0 of Pseudomonas fluorescents, and Bacillus subtilis and non-primed (control) and three levels of salinity stress (0, -4 and -8 bar). Results indicated that salt stress reduced germination (up to 40%) and seedling indices of cumin under -4 and -8 bar, the highest germination percentage, germination rate, seedling length, and seedling vigor index were achieved in the seeds inoculated with P. fluorescens, CHA0. At all levels of stress, seed bio-inoculation were increasing the seed soluble protein content compared to non-primed. The effect of this treatment was more obvious under salinity potential of -8 bar. The results indicated that salinity can affect cumin seed germination and the beneficial effect of PGPR could be used for improving its salt tolerance.