Evaluation and Exploration of Citrus Germplasm Resources in the Origin of Shatangju (Citrus flamea Hort.ex Tseng Shiyueju)

[Objectives] To protect the local rare citrus germplasm resources and further develop and cultivate new citrus varieties. [Methods] The germplasm resources of Shatangju (Citrus flamea Hort. Ex Tseng Shiyueju) in Sihui City of Guangdong Province and other 8 citrus varieties from the same origin were evaluated. The appearance characteristics of tree shape, the length and thickness of shoot at each shoot stage, the appearance characteristics of leaves and the fruit quality of each variety were investigated. [Results] Through the comparison of various citrus varieties grafted with sour mandarin, the results showed that the overall advantages of the length and thickness of the shoots of Shatang tangerine in summer and autumn were more prominent, which was conducive to fruit setting. The sprouting time of the three shoots of each variety was different, and there were sporadic sprouting phenomena in different seasons, so the growth was different, and the length and thickness of the shoots were different in different seasons. There were significant differences in shoot length and diameter among different varieties in the same season. The coefficient of variation of Shatangju’s leaves was low, and the traits were stable; leaf shape, leaf base shape, leaf margin and other indicators among the three shoots of the same variety and the differences among the same shoots of different varieties were compared. All varieties had strong flavor, separately sweet and sour, sweet and sweet taste. Shatangju has many segments, orange pericarp, rough texture, easy peeling, and high oblate fruit shape. The orange pericarp was favored by the participants, while the rough and thick peel was not favored by the participants. [Conclusions] Based on the improvement of local varieties, it is recommended to improve the smoothness of pericarp, reducing the thickness of pericarp and improving the flavor of fruit will be conducive to increasing sales. In the cultivation process of various quality resources, especially in the period of fruit growth and development, the plan of nutrition and fertilization should be formulated according to the rules of fruit growth and development, the rules of yield formation and the rules of quality composition, so as to establish the integrated nutrient management system of various varieties.