Flower color determination and bract pigment composition analysis of different Bougainvillea spectabilis Willd. varieties

Bougainvillea spectabilis Willd. species are typical tropical flowers of great ornamental value due to their colorful bracts. To study the relationship between bract color and pigment composition in Bougainvillea, the bract color phenotypes of 10 Bougainvillea varieties were measured using a colorimetric card and color difference meter. Pigment composition was identified by ultraviolet-visible (UV-Vis) spectroscopy and quantitatively analyzed. Results showed that the 10 varieties could be divided into five color systems:i.e., white, yellow, orange, red, and purple. Quantitative analysis showed that bract pigment composition was in the order of flavonoids, chlorophyll, and beet pigment. Correlation analysis of color phenotype and pigment content showed that flavonoids, betacyanin, and betaxanthin were the most important factors affecting the color of Bougainvillea bracts.