Plant growth-promoting bacteria and silicon fertilizer enhance plant growth and salinity tolerance in Coriandrum sativum

Plant growth-promoting bacteria (PGPB) and silicon (Si) can augment salinity tolerance in plants. In this study, 25 potential PGPB were isolated from alfalfa rhizosphere and screened for their ability to synthesize indole-3-acetic acid, 1-aminocyclopropane-1-carboxylate deaminase, and solubilize tricalcium phosphate. Two promising strains were tentatively identified as Pseudomonas pseudoalcaligenes (KB-10) and P. putida (KB-25) based on phenotypic, biochemical and 16S rRNA gene phylogeny. Subsequently, a pot experiment was conducted to evaluate the effectiveness of KB-10 and KB-25 treatment, alone or in combination with Si fertilizer, in alleviating salinity stress in coriander. The results showed that treatment with PGPB strains and/or Si significantly increased relative water content, concentrations of photosynthetic pigments, peroxidase activity, total biomass, salt tolerance index, and reduced salt-induced total phenolic contents. Overall data suggested that the combined application of PGPB and Si fertilizer could be a feasible and effective approach to improve growth and salinity tolerance in coriander.