Roohallah Saberi-Riseh - Department of Plant Protection, Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Iran.
Fariba Fathi - Department of Plant Protection, Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Iran.
Mojtaba Moradzadeh-Eskandari - Department of Plant Protection Research, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad, Iran.

One critical environmental stress that limits plant production and development is salinity stress. Recently it has been shown that application of plant growth-promoting rhizobacteria (PGPR) can alleviate the deleterious effects of environmental stresses. Present study aimed to evaluate the effects of some bacterial strains on proline, sugar, total phenolic compounds (TPC), Phenylalanine ammonia lyase (PAL), photosynthetic pigments and antioxidant activities (guaiacol peroxidase, polyphenol oxidase and superoxide dismutase) of cucumber plants under salinity stress. A completely randomized design was applied with a factorial arrangement of two factors: salinity at three levels (۰, ۵۰ and ۱۰۰ mM) and Pseudomonas fluorescens and Bacillus subtilis strains, with three replications. The results showed that cucumber plants that were inoculated with Pseudomonas and Bacillus strains possessed noticeable variations in proline, sugar, TPC, PAL and enzymes activity compared to un-inoculated control. These results suggest that use of these bacterial strains overcame harmful effect of salinity by accumulation of proline, TPC, sugar, PAL activity and enzymes activity that can be considered as a suitable method to manage salinity stress.

Cucumber, Enzymes activity, Phenolic compounds, PGPR, Salinity stress