Changes of colors and pigment compositions during the senescence process of chrysanthemum morifolium

The study aimed at exploring the mechanism of chrysanthemum floral coloration during the senescent process. 317 chrysanthemum cultivars including seven color groups from " Chinese chrysanthemum germplasm resources preservation center"in Nanjing Agricultural University were used as the test materials for field investigation. As a result, there were 202 varieties with color change. 109 varieties with obvious color change in different color groups during three flowering stages were selected for phenotype measuration using Royal Horticultural Society Color Chart and colorimeter. Furthermore, the determination of physiological parameters of five representative varieties'White Queen', 'Monalisa', 'Nannong Yukou'of white group, 'Nannong Lüdong'of green group, and 'Ibis-sunny'of yellow group were performed. It was showed that during the senescence of most chrysanthemum cultivars, the L∗values of petal surface were decreased, the a∗values were enhanced, e. g. the flower color gradually became more reddish than before. According to the determination of physiological parameters, the contents of flavonoids, especially anthocyanin contents in petals of five varieties showed a significant increase. In addition, the contents of MDA also gradually increased, while the contents of soluble sugar reduced. As a conclusion, the accumulation of anthocyanins probably affected by the changes of metabolic pathway is the key factor caused petals turning red during the senescence of chrysanthemum.