Evaluating Nonstructural Carbohydrates in Cranberry (Vaccinium macrocarpon Ait.) Cultivars and their Role in Fruiting

Abstract

Carbohydrate competition within cranberry (Vaccinium macrocarpon Ait.) uprights has been suggested to explain biennial bearing. Although, comparisons across cultivars during critical phenological stages are limited. The ensuing investigation sought to compare total nonstructural carbohydrates (TNSC). soluble sugars (SS), and starch concentrations across cultivars with varying biennial bearing and return bloom capability. Sugar concentrations of tissues and fruit were determined via high performance liquid chromatography for the cultivars Gryglesky Hybrid I (4GH1 '),'Stevens,' and 'HyRed' for the 2013 season. Lowest TNSC and SS concentrations in reproductive uprights occurred on 30 July, corresponding to late bloom/early fruit set and terminal bud development. Subsequently, TNSC and SS concentrations in 'Stevens' and 'Hy Red' increased, while 'GHl 'concentrations remained low. No differences in carbohydrate concentrations in fruit were found. Results support the hypothesis that carbohydrate competition in reproductive uprights contributes to biennial bearing via reduction in return bloom capability.