Copper oxide nanoparticles might be used to provide an essential mineral nutrient to growing maize seedlings, according to work published in the International Journal of Nanotechnology.
Nanoparticles are tiny particles, which can range from 1 to 100 nanometres in diameter, sometimes a little bigger. Metallic nanoparticles smaller than 1 nanometre are considered to be atomic clusters. Particles exceeding 500 nanometres are usually thought of as microparticles, unless they are nanotubes or fibres, which can be longer, but are nanoscopic in cross-section. Being nanoscopic gives a particle unique properties when compared with atomic clusters or bigger particles. As such they have been researched extensively across many different sectors, including materials science, engineering, medicine, and agriculture.
Given that copper is an essential nutrient for plant growth, the idea that copper, or more specifically copper oxide, nanoparticles (CuO NPs) might have useful properties to help plants assimilate the mineral readily and so to grow better has been discussed. Physicist Ali Raza of the University of Agriculture in Faisalabad, Punjab, Pakistan, and colleagues have investigated the effects of dosing the growing medium of maize seedlings with Cuo NPS. The researchers wanted to see how well the CuO NPs could enter and move through the plants, and if they would affect the growth of maize seedlings. They also needed to know whether this type of nanoparticle would be toxic. Metallic copper nanoparticles, as opposed to CuO NPs can have a positive effect on seed germination but are phytotoxic to growing wheat, Triticum aestivum, seedlings.
The basic conclusion from their study is that CuO NPs are taken up by the seedling roots and lead to improved growth over the course of eighteen days. The seedlings produce longer roots and shoots when dosed with CuO NPs, even at the relatively high concentration of 800 milligrams per litre of CuO NPs the nanoparticles were not toxic to the seedlings.
However, chlorophyll content fell and catalase activity decreased, which would ultimately have a deleterious effect on photosynthesis above that concentration. Samples dosed at 550 milligrams per litre (mg/l) showed a proportionately lower enhanced growth rate when compared to the 800 mg/l samples and against undosed control, suggesting a dose-related uptake at these concentrations.
The team suggests that the nanoparticles have a beneficial regulatory effect on enzyme activity in the seedlings, given that copper is a component or co-factor in many plant enzymes.
Raza, A., Ahmad, S., Mateen, A., Arshad, A., Rehman, A. and Oliveira, H.A.L. (2022) ‘Effect of copper nanoparticles on growth parameters of maize seedlings’, Int. J. Nanotechnol., Vol. 19, No. 12, pp.1143–1157.