COMPARATIVE ANALYSIS OF FOLIAR APPLICATION OF ELEMENTAL SELENIUM AND SE-NANOPARTICLES ON PLANT GROWTH

Abstract

Background: Selenium (Se) is a vital trace micronutrient whose deficiency poses a significant global population health concern due to its unequal distribution in agricultural lands as well as insufficient bioavailability in plant foods.

Objective: This study aimed to isolate and characterize selenium-resistant plant growth-promoting bacteria from agricultural soil and biosynthesize selenium nanoparticles. It comparatively evaluated the effects of Se-NP foliar spray application on growth, biomass, protein content, and chlorophyll pigments in Lactuca sativa under greenhouse conditions.

Methods: Fifteen bacterial isolates were screened for selenite reduction; five Se-reducing strains (A1-SER–A5-SER) were selected and characterized morphologically and biochemically including heavy-metal resistance, and auxin production. Biogenic Se-NPs were tested as a foliar spray in a 6–7-week greenhouse trial against bacterial inoculation and elemental selenium assessing fresh weight, soluble protein, and photosynthetic pigments.

Results: All strains were Gram-positive, spore-forming rods, catalase-positive, selenite-tolerant, and grew optimally at 28°C / pH 7 with resistance to Nickel, Zinc, and Manganese, and high levels of auxin production. Se-NP foliar spray outperformed other treatments increasing biomass (18.6 g) and chlorophyll A content (4.901 µg/g fresh weight).

Conclusion: Biogenic selenium nanoparticles synthesized from locally isolated selenium-resistant bacteria, applied as a foliar spray, proved most effective for selenium biofortification and plant growth promotion among the treatments tested. This approach offers a cost-effective, sustainable strategy for micronutrient management and lays a foundation for microbial nanotechnology applications in addressing crop micronutrient deficiency.