Abstract: To investigate the effects of nano-copper oxide (nano-CuO) on crop growth and physiological-biochemical characteristics, pepper (Capsicum annuum L.) was used as the test material. Five treatments were set up: CK(0 mg/L), A1(10 mg/L), A2(20 mg/L), A3 (50 mg/L), and A4 (100 mg/L). Various physiological and biochemical indicators were measured under different concentrations of nano-CuO solution, including seed germination rate, photosynthetic characteristics of pepper leaves, and antioxidant enzyme activities. Additionally, the cytoskeleton of pepper radicle cells was observed under different concentrations of nano-CuO solution. The results showed that soaking pepper seeds with different concentrations of nano-CuO solution had an inhibitory effect on seed germination, with the most significant effect observed in the A3 treatment. Compared with CK, the germination rate decreased by 25.6 percentage points. Irrigating pepper plants with different concentrations of nano-CuO solution promoted the net photosynthetic rate (Pn), with the best effect observed in the A4 treatment, where Pn increased by 50.4% compared with CK. Irrigation with different concentrations of nano-CuO solution also enhanced the activities of NAD-MDH, CAT, SOD, and POD enzymes in pepper leaf tissues. The most significant increase in NAD-MDH activity was observed in the A1 treatment, and the greatest increases in CAT, SOD, and POD activities were observed in the A3 treatment. Soaking pepper seeds with different concentrations of nano-CuO solution exerted certain effects on the cytoskeleton of pepper radicle cells. Specifically, under the A3 treatment, cortical actin filament signals in the cells were enhanced, and stress fibers became more numerous and thicker.

Key words: nano-copper oxide, pepper(Capsicum annuum L.), cytoskeleton, photosynthetic characteristics, antioxidant enzymes, growth and development