Optimization of Phytosynthesized Zn–Se Nanocomposites via Response Surface Methodology: Characterization and Germination Impact on Gamma‐Irradiated <scp><i>Brassica napus</i></scp> L.

The sustainable synthesis and optimization of nanocomposites (NCs) for agricultural applications remains a critical challenge. This study addresses this issue by developing Zn-Se NCs using green synthesis methods with Allium sativa and Mentha arvensis plant extracts optimized via Response Surface Methodology (RSM) to achieve an average size of 34.9 nm. For the first time, the combined application of NCs and gamma irradiation was evaluated to enhance seed viability and early growth in Brassica napus L. in the present study. The results indicated that p-values of 0.0001 and 0.0032 for the linear and quadratic regression models, respectively, were significant. The UV-visible spectrum of Zn-Se NCs showed a sharp peak at 295 nm, while FTIR spectra identified functional groups acting as a reducing agent, detailing their compound class, peak shape, and intensity. Spherical Zn-Se NCs were synthesized with an average size of 34.9 nm. The effects of optimized Zn-Se NCs on germination parameters were assessed, revealing that the percentage germination was non-significant, with a p-value > 0.05. In contrast, the survival rate, seedling length, and seed vigor index (SVI) were significant, with p-values of 0.002, 0.007, and 0.015, respectively. The results demonstrated significant improvements in germination percentage and seedling vigor, highlighting the potential of NCs as a nanobiofertilizer. This study presents a novel green synthesis approach for Zn-Se NCs using Allium sativa and Mentha arvensis plant extracts, achieving precise size control (< 35 nm) through RSM optimization, enhancing bioavailability and eco-friendliness. This study recommends the use of plant-mediated Zn-Se NCs in combination with gamma irradiation as a sustainable and effective approach to improve crop productivity and promote eco-friendly agricultural practices.