First insight into diversity of leaf color of loquat (Eribotrya) and its potential value on taxonomy

Leaf morphology is the most intuitive and representative feature that has been applied into field identification and determination of the genetic diversity of loquat germplasms. Using a colorimeter, we analyzed the leaf color traits of 234 loquat accessions in early spring, when four types of leaves (tender leaf on young shoots, mature leaf on autumn shoots, aging leaf on spring shoots and living defoliation) were sampled to measure their front and rear color parameters ( L * , a * , b * , C * , H * , E * ). Both leaf images and Shannon’s index ( I ′: 1.76 to 2.00) demonstrate the high diversity of leaf color; Principal Component Analysis shows that a * and b * are mostly significant in cluster analysis. The front and rear color parameters of four types of leaves were respectively clustered, and five dendrograms were selected based on their representative performance on classification. The five-digit search number, which indicates the main cluster of the five dendrograms for each germplasm, and grandient color blocks, which describe the color range of each main cluster, contribute to establishing a taxonomy index. Results demonstrate that loquat leaf color traits not only help to classify the ten species, which fit the Eriobotrya botanical classification and discriminate several landraces and regional resources, but also speed up the classification process and make it intuitive and efficient.