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 demands innovative strategies to enhance crop productivity and stress resilience while minimizing environmental impacts. Plant growth–promoting bacteria (PGPB) and biogenic selenium nanoparticles (SeNPs) have individually demonstrated significant potential in improving plant performance; however, their combined effects on crop physiological and biochemical responses remain largely unexplored.
In this study, twenty selenium (Se)-resistant Gram-positive bacterial strains were isolated from agricultural soils and screened for essential plant growth–promoting traits, including nitrogen fixation, phosphate solubilization, and phytohormone production. Selected strains were subsequently used to inoculate Lactuca sativa (lettuce) seeds under semi-field conditions. Experimental treatments comprised bacterial inoculation alone, foliar application of SeNPs alone, and a combined application of both.
After six weeks of growth, key plant growth parameters (root length, leaf length, and fresh weight) were assessed alongside biochemical attributes, including photosynthetic pigment content (chlorophyll a, chlorophyll b, and carotenoids), soluble protein concentration, and peroxidase activity. The combined application of selected bacterial strains and SeNPs resulted in a significant enhancement of lettuce growth and stress-related biochemical responses. Notably, the NB11 + SeNP treatment increased soluble protein content by 75% and peroxidase activity by 65% compared with the control (p ≤ 0.05).
Heat map analysis revealed strong positive correlations between growth and biochemical parameters under combined treatments, while principal component analysis (PCA) showed that the first three components accounted for 77.1% of the total variance, clearly distinguishing the combined treatments from the other experimental groups.
Overall, these findings demonstrate that the synergistic application of Se-resistant PGPB and SeNPs represents a promising bio-based strategy to enhance plant growth, stress tolerance, and nutritional quality. This approach offers a sustainable and environmentally friendly alternative to conventional chemical fertilizers, particularly in stress-prone agroecosystems
