S13 - Session O2 - Effects of foliar application of zinc nanoparticles in lettuce (Lactuca sativa L.) plants

Authors: Ruta Sutuliene *, Jurga Miliauskiene, Ausra Brazaityte, Simona Tuckute, Martynas Urbutis

Nowadays various metallic nanoparticles (NPs) are increasingly incorporated into agricultural products, but to date, there are still huge gaps in knowledge of the plant uptake capacity, permissible limit, and ecotoxicity of different NPs. Understanding the interactions between NPs and plants is crucial in the comprehension of the impact of nanotechnology on agriculture with a focus on plant toxicity concerns and risks to human health. Foliar spray of NPs is increasingly employed in agriculture but the data regarding foliar uptake of NPs, associated biophysiochemical changes inside plants, and possible health hazards are limited. Zinc (Zn) belongs to the micronutrients with poor bioavailability, though this element is essential for the vital functions of plants. In this respect, this study determined the effect of nano-enabled Zn (ZnO-NPs) delivery via the foliar application on Zn accumulation, physiological and biochemical changes in lettuce ( Lactuca sativa L. cv. Little Gem). Plants were grown hydroponically in controlled environment growth chambers (PFD ‒ 220 µmol m -2 s -1 , 18 h photoperiod, 21/17 +- 2 ºC temperature, 60% +- 5% relative humidity) and exposed via foliar spray to varying particle size of ZnO-NPs (18, 40 and 140 nm) at a concentration of 200 ppm. The experimental results revealed that the foliar spray of ZnO-NPs caused no visual damage in lettuce leaves, resulted in improved fresh and dry biomass, leaf area, affected leaf chlorophyll and flavonol indexes, macro-and microelement uptake. ZnO-NPs treated lettuce leaves contained higher amounts of Zn. After foliar ZnO-NPs spray, phenolic compounds, antioxidant capacity (ABTS, DPPH, FRAP assay), and antioxidant enzyme (CAT, SOD, APX, GR) activity were affected. These results indicate that the application of ZnO-NPs could be employed in lettuce production to improve yield, quality, and nutraceutical properties. Acknowledgements: This project has received funding from the Research Council of Lithuania (LMTLT), agreement No. S-MIP-21-27.