Silicon Application and Rhizobacterial Inoculation Regulate Mung Bean Response to Saline Water Irrigation

The present investigation examined the effects of silicon application and inoculation with the plant growth-promoting rhizobacteria (PGPR) Enterobacter cloacae and Bacillus drentensis on alleviating ion toxicity, regulating osmolytes accumulation, and productivity of field-grown mung bean under saline water irrigation. Inoculated seeds were grown in sandy loam soils (electrical conductivity: 2.78 dS m(-1)) and irrigated with water with three salinity levels (3.12, 5.46, and 7.81 dS m(-1)) using a drip irrigation system. Foliar application of silicon was conducted twice (3 wk after sowing and at flowering stage) at 1 or 2 kg ha(-1). The silicon application and PGPR inoculation countered the adverse effects of salinity on mung bean by decreasing proline, total phenols, and lignin contents in leaves and increasing the total soluble sugars in comparison to the control. Silicon and rhizobacteria also reduced Na+ content and increased K+, Ca2+, and Si contents in shoots compared to the control under all salinity levels. Furthermore, the significant interaction between Si and PGPR increased the pod yield. Among the treatments, Si (2 kg ha(-1)) application and B. drentensis inoculation remained the most prominent for the studied traits at all salinity levels. Thus, the current study suggested that application of rhizobacteria along with Si mitigates the effects of salinity on mung bean by regulating osmolytes, reducing lignification, improving mineral uptake, and decreasing tissue Na+ content.