To synthesize CuO, copper nitrate trihydrate [Cu(NO₃)₂.•3H₂O, 241.60 g/mol] (Neon reagents, Brazil) was used as Cu source. The extract was prepared with distilled water and commercial yerba mate. The germination and physiological parameters tests were carried out using tomato (Solanum lycopersicum) and lettuce (Lactuca sativa) seeds. The yerba mate and the seeds of tomato and lettuce were purchased at a local market in Florianópolis, Santa Catarina, Brazil (27°35'43.4"S,48°32'52.8"W).