Enhancing the sustainability of faba bean (Vicia faba L.) cultivation in Algerian oasis agroecosystems using drought-tolerant rhizobacteria

Abstract

The present study aimed to isolate, characterize, and evaluate drought-tolerant plant growth-promoting rhizobacteria (PGPR) from Saharan endemic legumes for their potential to enhance nitrogen fixation, growth, and yield of Vicia faba L. under deficit irrigation. Rhizobacteria were isolated from root nodules of native species (Retama raetam (Forssk.) Webb & Berthel. and Vachellia tortilis subsp. raddiana (Savi) Kyal. & Boatwr.) and identified using morphological and 16S rRNA gene sequencing analyses. Their drought tolerance was assessed using polyethylene glycol (PEG-6000), while plant growth-promoting traits, including phosphate solubilization and ACC deaminase activity, were evaluated in vitro. Selected strains were further tested under field conditions in an Algerian oasis system with two irrigation regimes: full irrigation (100 % crop water requirement) and deficit irrigation (50 %). Inoculation significantly improved nodulation, nitrogen fixation, plant water status, and seed yield under water-limited conditions compared to non-inoculated controls. These findings demonstrate that indigenous drought-adapted PGPR represent effective and sustainable biofertilizers for enhancing legume productivity in arid environments. This approach offers a promising, eco-friendly strategy to improve the resilience and sustainability of oasis agriculture under increasing water scarcity.