After characterizing the CuO NPs, we aimed to verify their effects on seeds of agronomical interest, such as tomatoes and lettuce. The effects of CuO NPs in plants are still poorly understood and the data available is inconsistent, largely due to the variety of experimental conditions of the different studies. The mechanisms by which CuO NPs act in plants are also unknown, but there is a strong possibility that they interact with reactive oxygen species (ROS) and may interfere with or improve cell metabolism .