Effect of Exopolysaccharide-Producing Bacteria and Melatonin on Faba Bean Production in Saline and Non-Saline Soil

Abstract

Soil salinity is a major threat to modern agriculture, as it affects crop growth and development. The present study focuses on the integration of eco-friendly biostimulants in salinity stress as a strategy to achieve the alleviation of abiotic stress. Field experiments were conducted at two locations, consisting of saline and non-saline soil, to investigate the utilization of exopolysaccharide (EPS)-producing bacteria (Azotobacter chroococcum) and melatonin at different concentrations (0, 25, 50, and 100 µM) for alleviating the adverse effects of salinity on the growth and production of faba bean plants. Salinity stress caused a reduction in all measured parameters of the faba bean plants grown in the saline soil relative to the plants grown in the non-saline soil. The addition of bacteria and/or melatonin significantly increased the growth parameters and yield components under both soils compared to the respective control plants. Both bacteria inoculation and melatonin application enhanced N, P, and K concentrations; the proline content; RWC%; and the K+/Na+ ratio; however, Na+ and Cl− concentrations were decreased significantly in salt-stressed faba beans. The combined use of bacteria and melatonin exhibited the highest stimulating effects. The present study recommends the combined use of EPS-producing bacteria and melatonin for the salinity stress management strategy of faba bean.