Phytohormonal Priming by Gibberellic Acid for Enhance Tolerance of (Chenopodium quinoa L.) and their Oxidative Homeostasis to ZnO NPs Phytotoxicity

The seed priming approach represents a viable, economically accessible, and sustainable management strategy for agricultural practices. This study investigates the ameliorating effects of 0.1 mmol gibberellic acid (GA3) as a phytohormonal priming agent on the growth and antioxidant system of quinoa (Chenopodium quinoa L.) under the phytotoxic effects of zinc oxide nanoparticles (ZnO NPs) at concentrations of 0, 50, and 100 mg L−1. Zinc oxide nanoparticles are known to inhibit growth traits in quinoa, including fresh and dry mass as well as chlorophyll a content. This growth inhibition was associated with alterations in metabolic pools, specifically reductions in soluble carbohydrates and soluble proteins in the shoots. Furthermore, both enzymatic antioxidants and phenolic compounds, which serve as non-enzymatic antioxidants, were significantly inhibited by ZnO NPs but were stimulated by GA3 priming. In conclusion, the hazardous effects of ZnO NPs can be at least partially mitigated by priming quinoa seeds with gibberellic acid (GA3), highlighting the potential of this strategy to enhance plant resilience against environmental stressors.