Prospects of ZnO-Nanoparticles for Zn Biofortification of Triticum aestivum in a Zinc-Solubilizing Bacteria Environment

An estimated 1.1 billion people are at risk of Zn deficiency due to the consumption of a Zn-poor wheat-based staple diet. Some soil bacteria can solubilize insoluble Zn in soil, significantly improving its bioavailability to plants. This study compares ZnO-nanoparticles with ZnO-bulk for the biofortification of Triticum aestivum in the presence of Zn-solubilizing biofertilizer prepared in this study. Various concentrations of ZnO-bulk and similar to 20 nm ZnO-NPs were tested. Two effective Zn-solubilizing bacteria with multiple plant growth-promoting traits were used for formulating a Zn-biofertilizer. Polyphasic approaches identified these strains as Streptomyces venezuelae and Klebsiella aerogenes. The biofertilizer was used to grow Triticum aestivum in the presence of either form of ZnO. Plant growth and health parameters (seed-germination rate, root and shoot length, fresh weight, dry weight, and chlorophyll content) show that a ZnO-NP concentration of 5 mg/L led to the most robust growth response. Atomic absorption spectroscopy of plant tissues verified that nano-ZnO results in better Zn uptake by the plant than the ZnO-bulk. A maximum increase of 22 and 44% in Zn-content of plant tissues was observed with bulk and nano-forms of ZnO, respectively. Results presented in this study suggest that ZnO-NPs can be used as a better source of Zn for plants and may help fight the menace of global Zn deficiency.