紫茉莉开花过程中花色和花色素的变化规律

紫茉莉是我国广泛分布的庭院花卉之一，具有丰富的花色。但不同花色紫茉莉在开花过程中的花色变化规律及其呈色机制还不清楚。以紫红色、黄色和白色紫茉莉为研究对象，分别通过色差仪测定法和紫外-可见分光光度法测定了不同开花时期不同花色紫茉莉花色表型及各类色素含量，探讨了其花色和色素变化规律，揭示其呈色机制。结果表明，从花蕾期到盛开期，紫红色紫茉莉花冠由淡绿色转变为紫红色，明度L^*值和色相b^*值减小，而色相a^*值、色度C^*值和色度角h值增大，叶绿素含量逐渐下降，类胡萝卜素、花色素苷和总黄酮含量逐渐升高；黄色紫茉莉花冠由淡绿色转变为黄色，盛开期具有最高的色度C^*值、色相a^*值和b^*值，整个开花过程具有较稳定的叶绿素和总黄酮含量，同时具有较高的类胡萝卜素含量；白色紫茉莉花冠由淡绿色转变为白色，过渡期具有最高的明度L^*值、色度C^*值、色相a^*值和b^*值，整个开花过程花色素苷和总黄酮含量较低，但随着开花进程逐渐升高，而类胡萝卜素含量稳定，过渡期总叶绿素含量显著低于其他2个时期。可见，不同花色紫茉莉开花过程中花色变化规律存在差异，而其差异性与其相应的色素成分变化密切相关。

Variation of Flower Color and Pigment Contents of Mirabilis jalapa During Flowering

Mirabilis jalapa， one of the widely distributed garden flowers in China， is rich in color， but the regulating mechanism of pattern and color of M. jalapa with different flower colors during flowering are still unclear. The color phenotype and pigment contents of the corolla of M. jalapa with different flower colors during flowering were which were tested by chromometer and ultraviolet-visible spectrophotometry respectively. The results showed that the corolla of purple red M. jalapa changed from light green to purple red from bud to bloom， and its values of lightness L^* and hue b^* decreased， but the values of hue a^*， chromaticity C^* and chromatic triangle h increased， the contents of chlorophyll decreased gradually， but the contents of carotenoid， anthocyanin and total flavonoid increased gradually respectively. The corolla of yellow M. jalapa changed from light green to yellow， had stable chlorophyll and total flavonoid contents， and higher carotenoid contents， its values of chromaticity C^*， hue a^* and b^* at blooming period were the highest. The corolla of white M. jalapa changed from light green to white， its values of lightness L^*， chromaticity C^*， hue a^* and b^* and the contents of the chlorophyll at transitional period were the highest， the contents of anthocyanin and total flavonoids were low， but increased gradually with the flowering process， and the contents of carotenoid were stable. It could be concluded that there were differences in the patterns of color changes during the flowering of M. jalapa， which were closely related with the pigment changes.