Leaf phenotypes and color transition patterns of eight Acer species during autumn coloration

Objective This research investigated the leaf phenotypic traits and pigment content dynamics during autumn coloration in eight native Acer species in China. The study aimed to reveal interspecific differences in leaf phenotype and color transition patterns, provide precise phenotypic and pigment content data to explore the genetic basis of interspecific variation in Acer species, and offer scientific guidance for selecting superior cultivars with early initiation and extended duration of color transition and vibrant foliage colors.

Method The leaf autumn coloration was divided into six stages (t1-t6). Principal component analysis (PCA) was conducted on 21 leaf qualitative traits, and variance analysis was performed on eight leaf quantitative traits. Leaf color parameters and pigment contents were measured, followed by correlation analysis.

Result (1) PCA of the 21 qualitative traits extracted five principal components, indicating that interspecific differences in leaf phenotype during autumn coloration were mainly reflected in leaf color, leaf lobe and serration structure, and leaf sinus depth. These traits can serve as key morphological criteria for distinguishing Acer species. Diverse interspecific variation was observed in quantitative leaf traits, including leaf length, leaf width, lobe length, lobe width, petiole length, and leaf base angle, during autumn coloration across the 8 Acer species. (2) Acer pseudosieboldianum entered the color transition period earliest (in mid-September) and had extended optimal ornamental period. A. pilosum var. stenolobum and A. pictum had the longest coloration period (over 40 days), providing a sustained and stable autumn landscape. (3) There were significant interspecific differences in leaf color parameters and pigment contents among the eight Acer species. A. truncatum and A. pictum exhibited particularly distinct and vibrant leaf coloration during the late autumn coloration. Correlation analysis revealed abundant relationships between leaf color parameters and photosynthetic pigment contents across the eight species, suggesting that the dynamic changes in anthocyanin and chlorophyll contents serve as the primary intrinsic regulatory mechanism driving the variation in leaf coloration among different Acer species.

Conclusion Significant interspecific differences were observed in leaf phenotypic characteristics and color transition patterns among 8 Acer species. A. pseudosieboldianum entered the coloration period earlier and exhibited diverse foliage colors, A. pilosum var. stenolobum and A. pictum had the longest coloration period, A. truncatum during the late autumn coloration exhibits distinct foliage coloration and demonstrates excellent ornamental value, making them recommended as autumn landscape tree species for horticultural greening in northern China.