Combining High-throughput Phenotyping and Multivariate Analysis to Assess Fruit Quality Traits in Southern Highbush Blueberry (Vaccinium corymbosum Interspecific Hybrids) Germplasm Collection

Abstract

Breeding blueberry cultivars with enhanced fruit quality requires simple, accurate, and cost-effective assays to select individuals from segregating populations. In this study, berry diameter, berry weight, firmness, pH, total polyphenol, total acids, D-glucose, D-fructose, total glucose, and total sugar content were quantified in 188 southern highbush blueberry selections and cultivars over 2 years. Significant variation between years, genotype, and year × genotype interaction was detected for all traits. Glucose and fructose were the predominant sugars, and they were in a range of 32.14–64.72 and 28.61–69.63 mg/mL, respectively. Total sugars content ranged from 62.22 to 131.15 mg/mL. Correlation analysis showed a strong positive correlation between total sugar content measured with the discrete analyzer and total soluble solids assessed as Brix (r2 = 0.96). In addition, glucose, fructose, and total glucose showed high and positive correlation between them and with the total sugar content. The titratable acidity was positively correlated with total acids (r2 = 0.60) and strong positive correlation between berry diameter and berry weight (r2 = 0.94) was detected. Principal component analysis (PCA) showed that PC1 explained 44.9% of the variation and the major contributing traits for diversity were D-fructose, D-glucose, total glucose, and total sugars. PC2 accounted for 21.2% of the variation and was mainly attributed to berry weight and diameter. Cluster analysis showed that the blueberry genotypes fell into two major groups. Cluster-I comprised genotypes with the highest amounts of total acids, pH, polyphenol, D-glucose, D-fructose, total glucose, and total sugar, whereas Cluster-II has genotypes with distinctly lower amounts of tested compounds and larger berries. Information obtained from this study is critical to identify superior genotypes for future crosses and advance evaluation. In addition, the firmness tester and discrete analyzer used in this study were invaluable in improving the efficiency and precision of phenotyping.