Individual Plant Growth Promoting Rhizobacteria from an effective consortiumstimulate different systemic protection in Oryza sativa against salt stress

Abstract: The aim of this study was to evaluate the individual capability of 5 PGPR strains,which co-inoculated demonstrated ability to protect rice plants against salt stress, to stimulate thesecondary metabolism of plant and protect them against salt stress. The strains used were:Arthrobacter oxidans BB1, Chryseobacterium balustinum AUR9, Bacillus sp. L81, Aeromonassp. AMG272 and Herbaspirillum sp. DSM6446. Seedlings growing for 7 days in hydroponic culturewere inoculated with PGPR, and 7 days after, NaCl was added to the medium to reach aconcentration of 3.5g/l. Two days later, the rate of wilt, the peroxidase activity (enzyme linked tostress situations), biometric parameters, and parameters related to plant photosynthetic efficiency(Fv / Fm, NPQ and ФPSII) were measured.Strains AMG272, L81 and Herbaspirillum were able to reduce the rates of withering up to80%, while BB1 and Aur 9 failed to protect the plants. The strains that protected against the saltstress, altered peroxidase activity and photosynthetic parameters following the guidelines set inthe literature of the process called “priming”.