Osmanthus fragrans, a culturally and economically significant plant in Asian countries, exhibits unique floral characteristics influenced by endogenous metabolites. Previous studies suggest its flowering timing and intensity may be affected by environmental factors including cold and darkness. This study aimed to investigate the effects of cold and darkness factors on the response of Osmanthus fragrans flowering and growth. This experiment included 7 cold and dark treatments (plants were sitting in the dark coolers from 0-15 days) and dark-only treatments (plants were sitting in the GH with plastic bags from 0-9 days). Plant responses were assessed based on the number of flowers, height, and width measurements on the 5th, 7th, 9th, 11th, 13th, and 15th days post-treatment. The results showed there was no significant difference in plant height across treatments. Dark-only treatment for 7 days significantly increased width growth compared to the control group (9 days), and dark-cold treatment for 5, 7, 9, 11, and 13 days. The increase in the number of flowers in the cold-dark treatment for 9 and 15 days was significantly higher than in other treatments, except for the control. In conclusion, the cold and darkness could promote flowering in Osmanthus fragrans without negatively affecting plant growth.
