Bamboo Biochar and Zinc Oxide Nanoparticles Improved the Growth of Maize (<i>Zea mays</i> L.) and Decreased Cadmium Uptake in Cd-Contaminated Soil

Cadmium (Cd) has attained top priority among all the toxic trace elements, and it easily accumulates in the human body through various pathways. The current pot study was focused on the impacts of foliar spray zinc oxide nanoparticles (ZnO NPs) (0, 50, 75, 100 mg·L−1), alone or combined with soil-applied bamboo biochar (1.0% w/w), on the maize growth and Cd and Zn accumulations in the grains of maize under Cd-contaminated soil. The results showed that the maize-growth, photosynthesis, and gas-exchange attributes were accelerated by the foliar-applied ZnO NPs, and this effect was further enhanced by the bamboo biochar application in combination with ZnO NPs. All the amendments decreased the electrolyte leakage (EL) and malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents, and they enhanced the activities of the antioxidant enzymes in the leaves and roots of the maize more than the control. The Cd concentrations in the shoots decreased by 74.55%, in the roots 66.38%, and in the grains by 76.19% after the bamboo biochar combined with a foliar spray of 100 mg·L−1 ZnO NPs. The current study concluded that the combination of the foliar spray of ZnO NPs and soil-applied bamboo biochar is a feasible strategy for safely growing crops on Cd-contaminated soils