with 25 and 50 mg/L of CuO NPs, as illustrated by lettuce seedlings (Figure ). An increase in dry mass was also detected in lettuce seeds treated with 25 mg/L CuO NPs (Figure ). Root and shoot growth show various responses to CuO NPs, having positive, neutral, and negative effects depending on the concentration and CuO NPs production. Essa et al. also reported an increase in the seedling growth of wheat after the application of CuO NPs in concentrations of 0.03 and 0.22mg/L, which is a similar concentration to what was used in our experiment. As pointed out by Feigl ,