Evaluation and correlation analysis of main quality traits of 54 cacao germplasm resources

【Objective】 In order to select excellent cacao germplasms with better quality traits, evaluation and correlation analysis were performed by 54 cacao core collections. The results could provide basic materials for cultivation of new cacao varieties, and supply a theoretical basis for the formation of cacao quality traits.【Method】 The main quality traits, cocoa butter content, polyphenol, fatty acid components(palmitic acid content, stearic acid content, oleic acid content, linoleic acid) and total content of fatty acids were performed with 54 different origins cacao germplasms from different countries, by ultrasonic ultra-isolation method, gas chromatography and Folin-Ciocalteu's method. Variability analysis, correlation analysis and cluster analysis were also performed.【Result】 Among 54 cacao germplasms, XYS53 showed the lowest cocoa butter content, palmitic acid content, stearic acid content, oleic acid content, linoleic acid content and total fatty acid content. XYS52 showed the highest cocoa butter content and total fatty acid content. XYS18, XYS17, XYS52, XYS44 and XYS20 showed highest phenotype on palmitic acid content, stearic acid content, oleic acid content, linoleic acid content and polyphenol content, respectively. The average of variation coefficient was from 1.52% to 18.74%, of which palmitic acid, linoleic acid and polyphenols showed larger variations with 18.74%, 18.62% and 14.42%. The variation coefficient of cocoa butter content was the smallest(11.52%). Correlation analysis showed that cocoa butter content was extremely significantly positively correlated with palmitic acid, stearic acid and oleic acid(P<0.01, the same below). There was an extremely significant positive correlation between palmitic acid and stearic acid, between palmitic acid and oleic acid, and between stearic acid and oleic acid. There was significant negative correlation between linoleic acid and palmitic acid(P<0.05, the same below). While polyphenols were negatively correlated with cocoa butter, palmitic acid, stearic acid, oleic acid and linoleic acid contents, but did not reach a significant level(P>0.05, the same below). There were no significant differences among cocoa butter content, stearic acid content, oleic acid content, polyphenol content and four fatty acids contents of different germplasm origin countries. However, there were significant differences of palmitic acid and linoleic acid contents between germplasms from China and Thailand. The results of principal component analysis and cluster analysis indicated that quality traits of 15 germplasm belonging to Group I performed well, these germplasms were maily from China and Vietnam.【Conclusion】 There is certain correlation between the main quality traits and different cacao germplasm origins. In the breeding process of selecting cocao varieties, by combining the correlation between traits and comprehensively considering the performance of cocao quality traits, 15 germplasms with excellent comprehensive traits from China and Vietnam can be preferred as breeding materials or parents to cultivate excellent cocao varieties.