Comparative efficacy of titanium oxide nanoparticles and zinc oxide nanoparticles against lead tolerance, growth performance and nutrient profiling of Brassica Napus L. grown under Lead contaminated soil

Abstract The lead (Pb) has been regarded as toxic metal that negatively impact both plant growth and human health. Due to limited information available about the application of titanium dioxide (TiO2-NPs) and Zinc oxide nanoparticles (ZnO-NPs) for the alleviation of Pb stress in crop particularly in Brassica napus L. The current experiment was aimed to investigate the efficacy of foliar application TiO2 and ZnO-NPs on Pb uptake and growth performance. The results of our study demonstrated that TiO2 and ZnO-NPs foliar application at (25, 50 and 100 mg/L) significantly decreased Pb uptake and simultaneously improved plant growth attributes, including shoot and root length, shoot and root fresh weight. Additionally, the NPs foliar application significantly augmented plant photosynthetic pigment (chlorophyll a, chlorophyll b, total chlorophyll and carotenoids) and gas exchange parameters compared to control. The biochemical analysis showed increased in plant antioxidative enzymes activities (peroxidase, Catalase, Superoxide dismutase) and reduction in oxidative stress (malondialdehyde, hydrogen peroxide, electrolyte leakage) under Pb stress upon NPs application. Importantly, foliar application of 100mg/L significantly reduced the uptake and translocation of pb in plant root and shoot with 45.7% and 84.1% respectively, as compared to control without nanoparticles. Furthermore, foliar application of TiO2 and ZnO-NPs enhance shoot zinc (Zn), iron (Fe), manganese (Mn), magnesium (Mg) calcium (Ca) and Potassium (K) when compared to control without nanoparticles. Interestingly concentrations of macro and micro nutrients with the type and dose of nanoparticles were varied. The highest concentrations of Ca (69.8%), Mn (67.3%) and Zn (78.7%) were found at 100mg/L ZnO-NPs foliar application while, the highest concentrations of Fe (79.4%), Mg (72.1%) and K (81.4%) were observed at 100mg/L TiO2 -NPs. Overall, application of nanoparticles especially, TiO2- NPs for Brassica napus L. is promising strategy for sustainable agriculture towards alleviating Pb toxicity and ensuring food security.