Objective To investigate the effects of carbon nanofertilizers on the growth of Siraitia grosvenorii cutting seedlings, providing technical support for establishing an efficient propagation technology system.

Method Using S. grosvenorii residue as the carbon source, carbon nanofertilizer A was synthesized with the addition of urea, carbon nanofertilizer B was prepared with the addition of rooting powder, and carbon nanofertilizer C was synthesized without any additives. Four concentration gradients of 0.4, 0.8, 1.6 and 4.0 mg/mL were set for carbon nanofertilizers A, B and C, recorded as treatments A1-A4, B1-B4 and C1-C4, respectively. Tap water was used as the negative control (NC), and 0.8 mg/mL potassium dihydrogen phosphate served as the positive control (PC), giving a total of 14 treatments. Using S. grosvenorii cuttings as the experimental material, each treatment was applied by foliar spraying. Growth indicators including plant height, stem diameter, leaf area, root vitality and seedling quality index, as well as antioxidant enzyme activities were determined.

Result Under the same concentration of carbon nanofertilizer, all indicators of S. grosvenorii cuttings in treatments with carbon nanofertilizer A were superior to those of carbon nanofertilizer B and carbon nanofertilizer C. In among all the treatments, treatment A2 achieved the best enhancement in the growth and physiological traits of S. grosvenorii cuttings. Under treatment A2, the plant height, stem diameter and dry weight of S. grosvenorii cuttings reached 26.13 cm, 2.15 mm and 6.93 g, respectively, which were significantly increased by 47.38%, 38.71% and 43.78% compared with NC, and by 38.47%, 28.74% and 29.05% compared with PC. Under treatment A2, leaf number, leaf area, root vitality and seedling quality index of S. grosvenorii cuttings were 9.39, 32.09 cm2, 0.78 mg/(g·h) and 3.85 g, respectively, which were significantly increased by 31.33%, 40.01%, 41.82% and 66.67% compared with NC, and by 18.26%, 21.69%, 27.87% and 37.99% compared with PC. Furthermore, treatment A2 significantly enhanced antioxidant enzyme activities of S. grosvenorii cuttings. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were significantly increased by 22.22%, 72.22% and 48.46% compared to the NC, and by 18.92%, 46.23% and 26.93% compared to the PC, respectively.

Conclusion Treatment A2 exhibited excellent growth-promoting and seedling-strengthening effects on S. grosvenorii cuttings, significantly elevateing antioxidant enzyme activities and enhancing the physiological resistance of plants.