Enhancing Metabolic Processes and Water Deficit Stress Tolerance of Maize Plants through Biochar Addition and Foliar Application of Zinc Nanoparticles

Abstract

The occurrence and intensity of drought events are escalating, and the overall availability of water is decreasing in many areas due to climate change. This study investigates the impact of water deficit on the growth and development of maize crops, exploring the potential alleviating effects of biochar (0.2%) and zinc oxide nanoparticles (100 ppm). Results indicate that water stress induced by varying concentrations of polyethylene glycol (PEG) reduced maize growth, with the highest PEG level (15%) resulting in a reduction of 35.4 and 54.8% in fresh and dry weights, respectively. Biochar (0.2%) significantly enhanced maize biomass, showing 41.2% more than non-stressed plants. It also improved the growth of maize subjected to drought stress. Water deficit leads to a gradual decline in photosynthetic pigments while applying biochar and ZNPs enhanced chlorophyll a, chlorophyll b, carotenoids, total carbohydrates, nitrogen contents, and protein compared to corresponding PEG-treated plants. Osmoprotectants, such as total soluble carbohydrates and proline, increased significantly under PEG treatment, while biochar and ZNPs further enhanced total soluble carbohydrate levels under both stressed and non-stressed conditions. However, these treatments reduce proline levels in PEG-treated plants. Compared to PEG treatments, Biochar, and ZNPs elevated K+, Ca2+, Mg2+, and Zn2+ levels. Biochar and ZNPs reduced catalase and peroxidase activities compared to corresponding stressed plants, the malondialdehyde content was also reduced. This investigation concluded that applying biochar and zinc nanoparticles could be a smart technique for strengthening plant physiological and biochemical status under water deficit conditions.