SYNERGISTIC IMPACT OF BIOGENIC SELENIUM NANOPARTICLES AND RHIZOBACTERIA ON LETTUCE GROWTH AND PHYSIOLOGY
Keywords:
Plant growth-promoting bacteria; Biogenic selenium nanoparticles; Rhizobacteria; Lettuce; Sustainable agriculture; Nano-enabled agriculture; Stress tolerance; Pigment stability; Plant–microbe interactionAbstract
Sustainable agriculture requires innovative strategies that enhance crop productivity and stress resilience while minimizing environmental impacts. Plant growth-promoting bacteria (PGPB) and biogenic selenium nanoparticles (SeNPs) have emerged as promising tools for improving plant performance; however, their synergistic effects on crop physiological and biochemical processes remain insufficiently explored.
In this study, twenty selenium (Se)-resistant Gram-positive bacterial strains were isolated from agricultural soils and screened for important plant growth-promoting traits, including nitrogen fixation, phosphate solubilization, and phytohormone production. Selected bacterial strains were applied as seed inoculants to Lactuca sativa (lettuce) under semi-field conditions. Experimental treatments included bacterial inoculation alone, foliar application of SeNPs alone, and a combined application of bacterial strains and SeNPs.
After six weeks of growth, plant performance was assessed through measurements of growth parameters (root length, leaf length, and fresh biomass), photosynthetic pigment contents (chlorophyll a, chlorophyll b, and carotenoids), soluble protein concentration, and peroxidase activity. The combined application of Se-resistant PGPB and SeNPs significantly improved lettuce growth and enhanced biochemical responses associated with stress tolerance. In particular, the NB11 + SeNP treatment increased soluble protein content by 75% and peroxidase activity by 65% compared with the control treatment (p ≤ 0.05). Heat map analysis demonstrated strong positive associations among growth and biochemical attributes under combined treatments, while principal component analysis (PCA) revealed that the first three components accounted for 77.1% of the total variance, effectively differentiating combined treatments from individual applications and control groups.
These findings demonstrate that the synergistic application of SeNPs and Se-resistant PGPB represents a promising bio-based strategy for improving plant growth, stress tolerance, and nutritional quality. This integrated approach provides a sustainable alternative to conventional chemical fertilizers, particularly for enhancing crop productivity in stress-prone agroecosystems
