| In this study, Peucedanum pratense seedlings was used as the research material. By measuring plant height, leaf area, biomass, water content, root\|shoot ratio and physiological indexes related to drought resistance of Peucedanum pratense, the effects of chitooligosaccharide (COS) at different concentrations (5, 10,15 mg·L-1 and 20 mg·L-1) on the growth and physiological characteristics in leaves of Peucedanum pratense under drought stress were studied. The results showed that the growth of Peucedanum pratense under drought stress was promoted at different concentrations of COS treatment, and with the increase of COS concentration, different growth indexes showed a trend of first increasing and then decreasing, and all had a certain optimal concentration. Compared with the single drought treatment, the number of leaves per plant in Peucedanum pratense treated with 5, 10, 15 mg·L-1 and 20 mg·L-1 COS were increased by 32.5%, 50.8%, 29.3% and 6.3%, respectively, all reaching significant levels (P<0.05), the average of leaf area per plant in Peucedanum pratense treated with 10 mg·L-1 and 15 mg·L-1 were increased by 27.3% and 20.8%, respectively, reaching significant levels (P<0.05), the plant height of Peucedanum pratense treated with 5, 10 mg·L-1 and 15 mg·L-1 COS was increased by 17.4%, 31.7% and 19.6%, respectively, and also reached significant levels (P<0.05). Compared with the single drought treatment, the proline content in leaves of Peucedanum pratense treated with 10 mg·L-1 COS was significantly increased by 11.8%. The H2O2 content and MDA content in leaves of Peucedanum pratense treated with 10 mg·L-1 COS were significantly decreased by 46.9% and 14.4%, respectively. Therefore, the drought stress of Peucedanum pratense seedling treated with 10 mg·L-1 COS was significantly alleviated (P<0.05). |