Enhancement of salinity stress tolerance in Cumin (Cuminum cyminum L.) as affected by plant growth promoting rhizobactria 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, this experiment was conducted in laboratory of seed science and technology, Yasouj University in 2016. Seed inoculations with plant growth promoting bacteria at five levels (seed inoculation with three strains of Pseudomonas fluorescens such as of Pf2, Pf25 and CHA0 and one strain of Bacillus subtilis and hydration in distilled water (as control)) and three levels of salinity stress (0, -4 and -8 bar imposed by NaCl) comprised experimental factors. Salt stress reduced germination percentage, catalase (CAT) and ascorbate peroxidase (APX) activities and seedling potassium content but increased its sodium. Seed inoculations with plant growth promoting not only mitigated the inhibitory effect of salt stress on studied characteristics but also in some cases induced a stimulatory effect on seed physiological quality in both stress and non-stress condition . 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 PGPR could be used to improve its salt tolerance