Calcination-tuned copper oxide nanoparticles for tomato seedling growth and vigour through nano-priming

Abstract

In the quest for sustainable agriculture innovations, nanotechnology is a critical tool for enhancing crop yields in fluctuating climates. This study investigated the potential use of copper oxide nanoparticles (CuO NPs) synthesized by Co-Precipitation and heat-treated for varying durations at different temperatures (200°C to 800°C, 2–6 h) as nano-priming agents for tomato (Solanum lycopersicum cv. Aahan F1) seeds. Structural and surface Characterizations, such as UV -Vis, XRD, FTIR, FESEM, DLS, and zeta potential, revealed that calcination temperature and time had a significant impact on particle size, crystallinity, and surface charge of CuO NPs. The best result was obtained by calcining at 600°C for 4 h, which produced particles with improved crystallinity, an average size of approximately 80 nm, and a zeta potential of −16.84 mV. These conditions favoured interactions between the seeds and the NPs. The tests indicated dose-response when seeds were treated with different NP concentrations, 5–100 mg/L. Low to moderate concentrations of 50–70 mg/L significantly improved germination rates, reaching up to 95 %, along with seedling vigour, biomass, and root-shoot growth. However, concentrations over 100 mg/L caused oxidative stress, which hindered growth and led to harmful effects on the plants. The influence of calcination time at a steady temperature (600°C) also showed that longer heating (6 hrs) resulted in clumping and less stability, while (4 hrs) offered the best colloidal properties and uniform shape. These results highlight the important role of heating conditions in optimising nanoparticle efficiency. This research suggests that calcination-engineered CuO NPs are an eco-friendly, scalable, and effective strategy for seed nano-priming that can promote early plant growth, serving as a promising alternative to traditional agrochemicals.