Biogenic selenium nanoparticles as nanopriming agents: Promoting germination and strengthening antioxidant defense in rice (Oryza sativa L.)

Abstract

Biogenic synthesis of nanoparticles is an emerging and trending technology. Greener approaches are more sustainable, less invasive and economical. The contemporary study focuses on the synthesis of selenium nanoparticles (Se-NPs) using Hibiscus rosa-sinensis leaf extract and evaluating their nanopriming effect on rice seeds. The biophysical characteristics of Se-NPs were evaluated using techniques like ultraviolet–visible spectroscopy, fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction, dynamic light scattering, scanning electron microscopy (SEM), atomic force microscopy (AFM) and electron probe microanalysis (EPMA). SEM and AFM analyses revealed spherical Se-NPs with an average diameter of 47.6 nm. FT-IR confirmed functional groups, aiding in the reduction and stabilization of the Se-NPs, while EPMA validated elemental selenium presence. Nanopriming with Se-NPs demonstrated a significant, dose-dependent increase in germination activity. This was evident in mean germination time (65 %), radicle and plumule length, fresh weight, and biochemical assays for total soluble sugar and protein content. Additionally, seed vigour and relative water uptake measurements strongly indicated that Se-NPs effectively boost germination and seedling growth. The reduction of free radicals was observed by 3,3′-diaminobenzidine and nitro blue tetrazolium staining, indicating strong antioxidant activity by application of Se-NPs. The increased activities of enzymes superoxide dismutase (SOD ≥28 %), catalase (CAT ≥46 %), peroxidase (POD ≥49 %), along with marked reduction in lipid peroxidation (MDA ≥23 %) evidently demonstrated that Se-NPs enhanced antioxidant defense. These findings suggest that selenium nanoparticles have bioactive potential in agriculture, particularly in improving plant growth. This warrants further exploration for efficient agricultural applications and creating a more sustainable environment.