Plant Growth Promoting Rhizobactria Enhance Salinity Stress Tolerance in Cumin (Cuminum cyminum L.) During Germination Stage

In order to investigate the effect of seed inoculation with Plant Growth Promoting Rhizobactria (PGPR) on germination and some biochemical and physiological indices of Cumin (Cuminum cyminum L.) under salinity stress, an experiment was conducted. Experimental factors were included in seed priming in five levels (seed inoculation with three strains of Pf2, Pf25 and CHA0 of Pseudomonas fluorescens, and one strain of Bacillus subtilis and hydration in distilled water (as priming control)) and three levels of salinity stress (0, -4 and -8 bar imposed by NaCl). Salt stress reduced germination percentage, catalase (CAT) and ascorbate peroxidase (APX) activities and seedling potassium content and increased sodium content. Priming not only mitigated the inhibitory effect of salt stress on studied characteristics but also in most cases induced a stimulatory effect on seed physiological quality in both stressed and non-stressed seeds. The highest germination percentage, APX activity and K+ content were achieved in the seeds inoculated with CHA0 strain of P. fluorescens. The effect of this treatment was more obvious under salinity potentials of -4 and -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.