Comparative Evaluation of Different Salt-Tolerant Plant Growth-Promoting Bacterial Isolates in Mitigating the Induced Adverse Effect of Salinity in Pisum sativum

Abstract

Due to climate change, salinity has become a limiting factor for many leguminous crops. Therefore, we have explored the comparative study of salt-tolerant plant growth-promoting rhizobacteria (PGPR) for the promotion of plant growth. These PGPR (Bacillus subtilis RhStr_71, Bacillus safensis RhStr_223, and Bacillus cereus RhStr_JH5) were in vitro screened for plant growth-promoting (PGP) traits such as IAA, P-solubilization, siderophore, and ammonia production. They were further selected to evaluate the maximum NaCl tolerant level (MTL). Selected salt-tolerant PGP bacteria were further characterized to evaluate their PGP activity on seedlings of Pisum sativum under 1% NaCl stress. They were further selected to perform the greenhouse experiments under 1% NaCl stress to compare these isolates on morphological (like plant height and weight) and biochemical parameters(such as carbohydrate, reducing sugar, protein, phenol, flavonoids, chlorophylls, and carotenoids). In a pot experiment, NaCl significantly reduced the plant growth parameters compared to un-inoculated and inoculated. Additional analysis also had shown that these strains also enhanced the antioxidant enzymes, thereby preventing oxidative damage caused due to reactive oxygen species (ROS). The result revealed that these salt-tolerant PGP bacteria exert their beneficial effects on plant growth and play a necessary role in attenuating the salinity stress in agriculture.