SYNERGISTIC EFFECTS OF BIOGENIC SELENIUM NANOPARTICLES AND RHIZOBACTERIA ON GROWTH, PHYSIOLOGICAL, AND BIOCHEMICAL ATTRIBUTES OF LETTUCE
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 approaches to boost crop productivity and stress resilience while reducing environmental impact. Both plant growth-promoting bacteria (PGPB) and biogenic selenium nanoparticles (SeNPs) have shown considerable potential in enhancing plant performance, yet their combined effects on crop physiology and biochemistry remain underexplored.
In this study, twenty selenium (Se)-resistant Gram-positive bacterial strains were isolated from agricultural soils and screened for key PGP traits, including nitrogen fixation, phosphate solubilization, and phytohormone production. Selected strains were used to inoculate Lactuca sativa (lettuce) seeds under semi-field conditions. Treatments included bacterial inoculation alone, foliar SeNP application alone, and their combined application.
After six weeks, plant growth parameters (root length, leaf length, and fresh weight), pigment content (chlorophyll a, chlorophyll b, and carotenoids), soluble protein levels, and peroxidase activity were evaluated. The combined application of selected bacterial strains and SeNPs significantly enhanced lettuce growth and stress-related biochemical responses. Specifically, the NB11 + SeNP treatment increased soluble protein content by 75% and peroxidase activity by 65% compared to the control (p ≤ 0.05). Heat map analysis revealed strong positive correlations between growth and biochemical traits under combined treatments, while principal component analysis (PCA) showed that the first three components explained 77.1% of the total variance, effectively distinguishing the combined treatments from other groups.
These results indicate that the synergistic use of SeNPs and Se-resistant PGPB provides a promising bio-based approach to improve plant growth, stress tolerance, and nutritional quality. This strategy offers a sustainable alternative to conventional chemical fertilizers, particularly in stress-prone agroecosystems.
