Enhanced enzymatic and bioactive compounds in lettuce via zinc oxide nanoparticles

Zinc (Zn) is a crucial micronutrient for living beings, yet the restricted availability of micronutrients in soil and the limited effectiveness of existing fertilizers often lead to deficiencies in crops, causing malnutrition in the population. Approximately 17.3% of the world's population suffers from health problems related to inadequate Zn intake. Nanobiofortification of crops is a strategy to mitigate this issue. The ‘Parris Island’ cultivar of lettuce (Lactuca sativa L.) was grown in 5-liter pots using a mixture of river sand and perlite (80:20 v/v) in a greenhouse environment. This study evaluated the effects of foliar application of zinc oxide nanoparticles (ZnO NPs) at concentrations of 0, 50, 75, and 100 mg L-1. ZnO NPs were applied four times at 15-day intervals. At 60 days post-transplantation, we assessed the fresh biomass, bioactive compound content, and bioaccumulation of Zn in lettuce. Results demonstrated that foliar spraying with 100 mg L-1 ZnO NPs enhanced Zn accumulation and the synthesis of bioactive compounds, thereby improving the nutritional profile of lettuce. Additionally, the 75 mg L-1 application increased fresh biomass by 103.23% compared to the control. This study provides compelling evidence of the potential of ZnO NPs as an effective nanofertilizer and biostimulant, presenting a promising approach to enhance Zn concentration and optimize antioxidant metabolism in lettuce plants.