WITHIN-SEASON STABILITY OF STRAWBERRY SOLUBLE SOLIDS CONTENT IN FLORIDA

Abstract

Several studies have documented significant variation in the soluble solids content (SSC) of strawberries (Fragaria x ananassa) during Florida's growing season. This fluctuation may result from variable physiological and environmental conditions interacting throughout the season. Cultivars with SSC stability would be valued in the commercial industry due to their more uniform quality. The stability of 385 genotypes from the strawberry breeding program at the University of Florida was estimated using the approach from Finlay and Wilkinson (1963). For each genotype a linear regression of SSC against the mean SSC of an independent set of genotypes at each harvest date was calculated. The magnitude of the slopes was considered an estimate of each genotype's stability. The means at each harvest date reflect the combined effects of physiological and environmental conditions that were common to all genotypes and served as estimates of how favorable conditions were for SSC during the relevant interval prior to harvest. Genotypes with steep slopes are sensitive to small changes in field conditions and are considered unstable compared to genotypes with slopes close to zero. Slopes ranged from flat to almost two times steeper than the population's value. About 87% of genotypes had average stability, whereas 7% were classified as unstable and the remaining 6% was considered stable. Results revealed that the within-season stability of SSC, as measured in this study, is a trait that shows significant variation across genotypes in the strawberry breeding program at the University of Florida. The analysis presented here is a starting point for understanding the genetic control of SSC stability. The repeatability of these results across different seasons has not yet been tested and will be examined in the future.