Analysis of fruit characters of 391 seedling longan germplasm resources in Guangxi

【Objective】The study analyzed fruit traits from longan seedling trees in different municipalities in Guangxi, in order to provide understandings of the diversity of germplasm resources and fruit trait characteristics, and reference for parent selection for breeding longan in Guangxi.【Methods】A total of 391 fruit samples from longan seedling trees in 7 municipalities were collected to measure and analyze the basic traits such as fruit size, mass and soluble solids content, frequency distribution and coef-ficient of variation (CV), correlation, and principal component analysis (PCA) and comprehensive score ranking was applied to systematically evaluate the fruits from different municipalities in Guangxi, so as to select excellent local germplasm resources.【Results】Longan plants in different ecological regions have not only morphological difference, but also significant differences in phenology, yield, quality characteristics, and stress resistance. The 391 seedling longan trees in Guangxi had their own characteristics in fruit size, single fruit quality, soluble solids and other quality traits, showing rich diversity. The results showed that there were significant differences in fruit traits among trees from different municipalities, with a coefficient of variation ranging from 8.82% to 30.90%. The magnitude of the coefficient of variation reflects the inherent characteristics of the variety and individual differences in biological products. The average values of single fruit quality, pulp quality, seed quality, peel quality, transverse diameter, and longitudinal diameter were 5.58 g, 3.34 g, 1.31 g, and 0.92 g, 21.47 mm, and 20.61 mm, respectively, with coefficients of variation of 26.15%, 30.90%, 23.75%, 29.61%, 9.10%, and 8.82%, respectively. The average flesh recovery and soluble solid content of fruits were 59.37% and 21.76%, respectively, with a coefficients of variation of 9.17% and 12.31%, respectively. The degree of variation of various fruit traits was in a order of flesh mass ＞ mass of pericarp ＞ mass of fruit＞mass of seed ＞ total soluble solids of juice＞flesh recovery＞transverse diameter＞longitudinal diameter. The average size of fruit (horizontal and longitudinal diameters) and mass (single fruit mass, pulp mass, seed mass and peel mass) were the highest in samples from Longzhou, while the highest average flesh recovery and soluble solids were found the samples from Guigang and Liuzhou, respectively. The fruit mass, soluble solid content and flesh recovery of the fruit were normally distributed. The concentrated area of single fruit mass distribution among all samples was 2.21-10.73 g; the concentrated area of soluble solid content distribution was 12.05%- 29.17% . The concentrated area of the flesh recovery distribution was 32.41%-84.86%. In addition to the soluble solid content, the sweetness of fruit longan had no significant correlation with other indicators; however, the flesh recovery was significantly correlated with fruit size and mass. The 391 seedling longan trees were analyzed by principal component analysis. Three principal components with characteristic roots greater than 1 were extracted by PCA, and the cumulative contribution rate was 92.276%. The first principal component explained 64.448% of the trait information which had absolute values include transverse diameter, longitudinal diameter, total fruit mass, total peel mass, total seed mass, and single fruit mass. The first principal component was related to single fruit mass. The second principal component explained 15.227% of the trait information that had a high correlation with flesh recovery. The third principal component explained 12.601% of the trait information that had a high correlation with the soluble solid content. Based on the component scoring coefficient matrix, the score of each sample on the corresponding principal component was obtained. The PCA method avoided subjective influence on evaluation of fruit quality. From the comprehensive performance, the coefficients of variation of mass of fruit, mass of thickness, mass of pericarp, and mass of seed were relatively large, showing rich variation. The fruit traits of the seven different regions had significant differences, mainly characterized by large single mass of fruit, high soluble solid content, all of which show rich genetic diversity. Due to the close geographical location of the surveyed actual longan, the segregation of traits was not obvious. Among the 9 fruit trait indicators of the 391 seedlings of longan, most traits showed significant or extremely significant positive correlations, while soluble solids content was negatively correlated with mass of fruit. The flesh recovery was highly significantly positively correlated with fruit mass and the longitudinal and transverse diameters of the fruit. The longitudinal diameter of the fruit was significantly negatively correlated with the content of solublesolids. It is inferred that germplasm with smaller single fruits tended to have higher soluble solids content.【Conclusion】The germplasm resources of seedling longan in Guangxi exhibit rich variation, with single fruit mass, flesh recovery, and soluble solid content being the main traits affecting longan evaluation. Samples from Heping, and Wuzhou and Anhuai in Guigang had outstanding single fruit mass performance; those Huanjiang Village, Chengzhong District, Liuzhou had a relatively high soluble solid content. The germplasm with high single fruit mass and excellent flesh recovery was found in Anhuai Town of Guigang, and the germplasm resources in the three municipalities can be developed and utilized for longan industry in Guangxi.