Nacre Color and Reflectance Spectrum Analyses of Four Selected Strains of Mussels, Hyriopsis cumingii

ABSTRACT Selective breeding of mussels based on nacre color forms the basis for cultivating freshwater pearls with specific colors, as the color of cultured pearls is mainly determined by the nacre color of the donor mussel. In this study, the nacre colors of four selected Hyriopsis cumingii strains (blue, red, golden, and white) were measured and analyzed. The results showed that the three nacre color parameters L*, a*, and b* significantly differed (P < 0.01) between the four H. cumingii strains. Two principal components (PC1 and PC2) were extracted based on a principal component analysis, and their cumulative contribution rate ranged from 92.81% to 93.44%. The color parameters a* and b* had the greatest influences on PC1 and PC2, respectively, indicating that these two color parameters were the main factors contributing to the nacre color differences of the four strains. The nacre color parameters of the four H. cumingii strains were also investigated extensively using discriminant analysis, and the discrimination accuracies of the four strains were 76.7%, 80.0%, 72.5%, and 100.0%. Reflectance spectrum analysis showed that the nacre reflectance spectra of the four H. cumingii strains differed considerably and the spectral reflectance curves of the different nacre colors were clearly separated, indicating that spectral analysis represents an effective method for identifying different H. cumingii strains.