Objective To study the effect of spraying exogenous trehalose on the color change of Acer rubrum (red maple) leaves, providing a theoretical basis for stabilizing the leave color change of colorful tree species or extending the ornamental period.

Methods One-year-old Acer rubrum 'freeman maple' potted seedlings were used as experimental materials. They were placed in a climate chamber with the leaves being sprayed with trehalose solutions of different concentrations at 5, 10, 20 and 30 mmol/L⁻¹. The control group was sprayed with clean water. The color parameters and physiological characteristics of the leaves in the four stages of color change, namely the pre-coloring, early, middle, and end stages, were analyzed to explore the key influencing factors.

Results Under low-temperature stress, spraying different concentrations of trehalose solution had different degrees of effect on the color change of Acer rubrum leaves. There was minor difference among the treatments in pre-coloring stage. As the leaves gradually turned from green to red, the color parameter a^* value changed significantly in the early, middle and late stages, demonstrating an upward trend. The content of photosynthetic pigments continued to decrease, whereas the contents of soluble sugar, anthocyanin and malondialdehyde increased. The activity of peroxidase and phenylalanine ammonia lyase also increased. Compared with each treatment, 10 mmol/L⁻¹(H₂) and 20 mmol/L⁻¹(H₃) exogenous trehalose solutions both increased the pigment content of the leaves, among which H2 solution significantly increased the content of soluble sugar, anthocyanin,and PAL activity, indicating its most significant effect. Correlation analysis showed no correlation between peroxidase activity and soluble protein on leaf color parameters, photosynthetic pigments, anthocyanin glycosides, malondialdehyde, and soluble sugars.

Conclusion The main factors affecting the reddening of Acer rubrum leaves during its color change period are soluble sugar content, phenylalanine ammonia-lyase activity and anthocyanins,.spraying 10 mmol/L⁻¹(H₂) exogenous trehalose solution could alleviate the damage caused by low-temperature stress on the leaves, promoting the color change with extended coloring period.