Integrating Phenotypic Analyses and Color Parameters: A Multidimensional Framework for Precise Color Characterization in Eggplant Fruit

Yiying Zhang^1,2Hairong Chen^1,2Shan Deng^1,2Qujiang Bai³Yu Zhang^1,2Hong Zhao^1,2Kun Liu^1,2Yunxia Chu^1,2*Li Ren^1,2*

• ¹Research Center for Agricultural Products Preservation and Processing, Shanghai Academy of Agricultural Sciences, Shanghai, China
• ²Shanghai Sub-Center for Plant New Variety Tests, Ministry of Agriculture and Rural Affairs, Shanghai, China
• ³Anshun University, Anshun, China

The accurate quantification of plant organ color remains a major challenge in plant variety identification, particularly when adjacent expression states exhibit subtle visual differences. This study addressed this challenge by integrating colorimetric, phenotypic, and genomic analyses of 137 eggplant germplasm resources to characterize fruit color. The CIELAB color parameters accurately represented fruit coloration and exhibited strong correlations with DNA fingerprinting results, while also aligning with the visual description of color characteristics based on DUS (Distinctness, Uniformity, and Stability) test guidelines. The color transition from harvest maturity to physiological ripeness was effectively captured by shifts in these parameters. Furthermore, the purple fruits at harvest maturity were subdivided into violet and red subcategories based on their CIELAB parameter distributions, and the yellow, ochre, and brown fruits at physiological ripeness were clearly separated through K-means clustering. Consequently, this study defined precise CIELAB ranges for each color category, offering a robust, multidimensional approach for objective eggplant variety identification and enhancing the reproducibility of color-based DUS evaluations.