ObjectiveFlower color is an important basis for the classification of peony cultivars, but the traditional color classification of peony based on visual measurement is more subjective and can't clearly define the color of peony. It is necessary to establish a more scientific classification system of peony cultivars based on the color phenotype.

MethodIn our research, 175 peony cultivars were selected to measure the flower color phenotype by colorimeter. Then the peony petal samples were named according to ISCC-NBS Method of designating colors as well as hierarchical cluster analysis and production experience.

ResultFinally, the peony cultivars were classified into eight groups, including white group, yellow group, light pink group, pink group, red group, purple group, dark red group and orange group. Each color group had correspondence with the L^*, a^*, b^* values of CIELab coordinate, so the quantitative description of the color of different peony cultivars can be realized. It indicated that the classification system was reasonable. What's more, the flower color of the peony cultivars is various and exists obvious difference among different cultivar groups.

ConclusionThe flower color of peony cultivars was scientifically classified in this study. The color group of different peony cultivars can be confirmed directly according to L^*, a^*, b^* values. It provides a theoretical basis for the classification and identification of peony cultivars and it's a standard for the description of flower colors in the circulation of peony market and scientific research. Also, it's important to breed new cultivars with new colors of peony.