Genetic and Environmental Variation in Southern Highbush Blueberry Flavor Components

Among traits selected for in the University of Florida southern highbush blueberry (SHB, Vaccinium corymbosum L. hybrids) breeding program, flavor is one of the most subjective.  In early stages of selection, flavor is judged in a non-quantitative manner by few individuals, while in later stages flavor is quantified by calculating sugar:acid ratios based on total soluble solids and titratable acidity measurements.  Additionally, the high level of environmental variation for flavor components makes breeding evaluation challenging. To identify potential breeding targets for flavor, we measured flavor components of six SHB genotypes (FL 06-377, ‘Emerald’, ‘Farthing’, ‘Meadowlark’, ’Primadonna’, and ‘Scintilla’) grown in three locations at three different time points in harvest season. The three locations were chosen for differences in production and management styles: high tunnel evergreen production in Waldo, FL; very low chill production in Haines City, FL; and no use of hydrogen cyanamide in Citra, FL. Total soluble solids (TSS) and titratable acidity (TA) were measured, and individual sugars were quantified using Sucrose/D-Glucose/D-Fructose enzymatic reaction kits. In all samples, D-fructose was detected in higher amounts than D-glucose, and sucrose was not detected in any of the samples. ‘Farthing’ was least variable in TSS across all nine harvests, while ‘Scintilla’ and FL 06-377 were least variable in TA throughout the season. When measurements were grouped by location, TSS were least variable at Citra, FL, while TA was least variable at Haines City, FL. In all but two cases, TA decreased throughout the season, and the lowest acid berries, excluding ‘Farthing’, were harvested from Citra, FL. In most cultivars, there was an increase in TSS as the harvest season progressed. However, at the third harvest in Waldo, FL, which was done during a rain, there was a drop in TSS for all samples. There was also a decrease in fructose and glucose present in all samples, except ‘Farthing’. Although there was a high degree of variation for measured flavor components overall, potential parents could be selected that had less variation for individual components.