Using Bacillus megaterium as a bio-fertilizer alleviates salt stress, improves phosphorus nutrition, and increases cauliflower yield

Abstract

The traditional crop production system involves the use of large amounts of chemical fertilizers, which negatively impacts the ecological environment by increasing soil degradation and salinity, threatening sustainable agricultural production. Therefore, there is an urgent need for agricultural practices that increase plant productivity and reduce negative impacts on the environment. Phosphate-solubilizing microorganisms can enhance nutrient availability and plant uptake. This study investigated the effect of Bacillus megaterium as a bio-fertilizer (inoculated and non-inoculated) combined with phosphorus fertilizer (40, 60, and 80 kg. ha−1) on the growth and yield of cauliflower grown under saline conditions, saline soil (9.68 dS.m−1) and saline irrigation water (7.12 dS.m−1). Salt-stressed cauliflower inoculated with Bacillus and fertilized with 60 or 80 kg. ha−1 P2O5 showed improved growth and higher yield compared to other treatments, without significant differences between them. However, Bacillus-treated plants fertilized with 60 P2O5 showed increases in superoxide dismutase (SOD) by 29.3%, catalase (CAT) by 13.9, chlorophyll by 10.4%, N by 7.8%, and P by 8.6%, while Na decreased by 7.8%, resulting in significant increases in cauliflower yield (head weight by 9.3%, and total yield by 8.3%) compared with the control treatment (recommended P fertilizer, 80 kg P2O5. ha−1). The results indicated that the inoculation of salt-stressed plants with Bacillus megaterium is a promising and feasible approach to reduce phosphorus fertilizer use by up to 25% and enhance membrane stability (MSI), relative water content (RWC), nutrient availability, and growth performance, thus mitigating the adverse effects of salt stress exacerbated by climate change.