Green synthesized iron oxide (Fe2O3) nanoparticle affects the germination and growth-related characteristics of different basil (Ocimum basilicum L.) cultivars.

Conventional methods for nanoparticle (NP) synthesis often rely on unsafe chemical reduction processes. Plant-mediated green synthesis of NPs has emerged as a promising alternative to such toxic reductants. Seed priming is an effective technique for improving seed germination and plant growth characteristics. Nano-priming outperforms traditional seed priming methods owing to the nanoparticles' nanoscale dimensions and unique physicochemical properties. In this study, the extract of Mentha pulegium L. plant was used for Fe2O3-NPs synthesis. Afterward, the seeds of four basil (Ocimum basilicum L.) cultivars (Dark opal, Iranian purple basil, Iranian green basil, and sweet basil) were treated with four concentrations of Fe2O3-NPs (0, 50, 100, and 200 ppm) for two exposure times (6 and 12 h) to evaluate seed germination and growth-related traits of the plants. The green synthesized NPs were characterized via different techniques, including UV-Vis absorption, Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results showed that the average size of the prepared Fe2O3-NPs was around 82.24 nm. The response of basil cultivars was completely dependent on the dosage administered, duration of exposure, and cultivar type, as lower concentrations of iron nanoparticles provided a positive response to seed germination and growth parameters of cultivars. However, in dark opal basil cultivar, maximum values for shoot length (20.73 ± 1.78 mm), root length (29.68 ± 1.87 mm), and root fresh and dry weights were achieved at 200 ppm with 12 h exposure time. The highest germination percentage (95%) among all cultivars was obtained in dark opal cultivar using 100 ppm Iron NPs and 12 h treatment. The use of green-synthesized iron NPs for seed priming offers advantages such as eco-friendliness, reduced toxicity, enhanced nutrient delivery, and improved germination efficiency compared to conventional methods.