Analysis and Evaluation of Camellia oleifera Abel. Germplasm Fruit Traits from the High-Altitude Areas of East Guizhou Province, China
Authors: Wan Xianqin , Sun Dongchan , Nie Yanmei , Wang Qimei , Zhang Tianfeng , Wang Rui , Li Feifei , Zhao Xudong , Gao Chao 
Published: April 2024

Abstract

This study analyzed the fruit quality of 48 Camellia oleifera Abel. germplasms from the high-altitude areas in East Guizhou Province, China, to select the superior ones with excellent and comprehensive performance. This study aimed to provide a theoretical basis and research foundation for the selection and breeding of high-quality varieties in high-altitude areas. For this, 15 main traits of mature fruits were measured and analyzed. These included single fruit weight, transverse and longitudinal diameters, peel thickness, fresh and dry seed yields, dry kernel yield, and oil yield. The levels of palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, and cis-11-eicosenoic acids were ascertained. A comprehensive evaluation using cluster and principal component analyses (PCA) was conducted. The cluster analysis revealed that the germplasms could be divided into five categories when the squared Euclidean distance was 14. The first category included 17 germplasms, the second included 28, and the third, fourth, and fifth categories included only one each. The PCA method was used to reduce the multivariate statistical dimensionality of the data, simplifying the 15 traits into five composite indices or principal components (PCs). PC1 had the highest eigenvalue of 3.57, with a contribution rate of 23.8%, principally representing the phenotypic traits. The contribution rate of PC2 was 20.44%, mainly representing linoleic acid; that of PC3 was 12.99%, primarily representing the oil content of the seed kernel; that of PC4 was 9.13%, predominately representing the fresh seed yield; and that of PC5 was 7.45%, predominantly representing palmitoleic acid. By employing a weighted sum method to acquire the PCs, a comprehensive evaluation function was established to obtain the total score of each superior individual. Final ranking and selection were based on these scores. Single fruit weight, peel thickness, and fresh and dry seed yields exhibited high variability, while the coefficient of variation for oleic acid was the lowest. The dry seed yield was significantly positively correlated with the seed kernel oil content and the concentrations of palmitic and linoleic acids. The seed kernel oil content was markedly negatively associated with the levels of only cis-11-eicosenoic acid. In total, five PCs with eigenvalues > 1 were extracted, and the top ten superior individuals with the highest comprehensive scores were selected. These were ranked as: QD-33 > QD-34 > QD-48 > QD-38 > QD-27 > QD-15 > QD-35 > QD-5 > QD-14 > QD-36. Thus, the 48 C. oleifera germplasms from the high-altitude areas of East Guizhou Province had a high scope for improvement in the traits of single fruit weight, peel thickness, and fresh and dry seed yields. The superior individuals QD-33, QD-34, and QD-48 demonstrated the best comprehensive performance and can be candidate resources for variety selection and breeding.