Su Xuexia, Bai Cuihua, Wang Xianghe, Liu Huilin, Zhu Yongcong, Wei Leping, Cui Zixiao, Yao Lixian
College of Natural Resources and Environment, South China Agricultural University, Guangzhou, China.
Guangdong Provincial Key Laboratory of Agricultural and Rural Pollution Abatement and Environmental Safety, Guangzhou, China.
Front Plant Sci. 2022 Jun 14;13:925609. doi: 10.3389/fpls.2022.925609. eCollection 2022.
Fruit color is a decisive factor in consumers' preference. The bright red color of litchi fruit is associated with its high anthocyanin; however, poor fruit coloration is a major obstacle in litchi plantation. The role of spraying mineral nutrient salts such as KHPO, KCl, KSO, and MgSO on litchi pericarp pigmentation was examined by a field trial, and the relation between human visual color preference versus pericarp pigments and hue-saturation-brightness (HSB) color parameters was investigated. KSO-sprayed litchi fruit gained the maximum popularity for its attractive red color. Spray of K and Mg salts decreased the buildup of yellowish pigments, but increased the accumulation of red ones, with the exception of slightly reduced anthocyanins in KHPO-sprayed fruit, by regulating the activities of enzymes involved in anthocyanidin metabolism and decreasing pericarp pH, leading to varied pericarp pigment composition. KSO spray generated the highest percentage of cyanidin-3-glucoside over all pigments in pericarp. Correlation analysis shows the percent of cyanidin-3-glucoside, superior to anthocyanin concentration and HSB color parameters, was a reliable indicator to fruit color preference. This work demonstrates that spray of suitable mineral salt can regulate pericarp pigment profile, and is an effective approach to improve fruit pigmentation and promote its popularity.
果实颜色是消费者偏好的决定性因素。荔枝果实的鲜红色与高花青素含量有关；然而，果实着色不佳是荔枝种植中的一个主要障碍。通过田间试验研究了喷施KHPO、KCl、KSO和MgSO等矿质营养盐对荔枝果皮色素沉着的作用，并研究了人类视觉颜色偏好与果皮色素及色调-饱和度-亮度（HSB）颜色参数之间的关系。喷施KSO的荔枝果实因其诱人的红色而最受欢迎。喷施K盐和Mg盐通过调节花青素代谢相关酶的活性并降低果皮pH值，减少了淡黄色色素的积累，但增加了红色色素的积累，喷施KHPO的果实中花青素略有减少除外，从而导致果皮色素组成各异。喷施KSO使果皮中矢车菊素-3-葡萄糖苷在所有色素中的占比最高。相关性分析表明，矢车菊素-3-葡萄糖苷的占比优于花青素浓度和HSB颜色参数，是果实颜色偏好的可靠指标。这项工作表明，喷施合适的矿质盐可以调节果皮色素分布，是改善果实色素沉着并提高其受欢迎程度的有效方法。
