Analysis of the ultraviolet–visible spectrum and relative anthocyanin content in
‘Purple Reagan’. A, Ultraviolet–visible spectrum analysis of flavonoids. B, Ultraviolet–visible spectrum analysis of carotenoids. C, Mass spectrum analysis of anthocyanin content using the HPLC method. D, The relative anthocyanin contents of different samples collected during five capitulum developmental stages detected by the HPLC method. The x-axis and y-axis in Figure 1A and B indicate the wavelength and absorption peak value, respectively. The x-axis and y-axis in Figure 1C indicate the running time and electric signal, respectively. The x-axis and y-axis in Figure 1D indicate the five capitulum developmental stages from S1 to S5 and the relative anthocyanin content, respectively.