Comparison of nonstructural carbohydrates across cranberry cultivars

摘要

Carbohydrate competition within reproductive (fruiting) uprights has been proposed to explain low fruit set and biennial bearing tendencies of cranberry (Vaccinium macrocarpon). Yet, comparisons of nonstructural carbohydrate concentrations during critical phenological stages across cultivars that differ in biennial bearing tendencies and return bloom potential are lacking. This study sought to address this deficiency by comparing total nonstructural carbohydrates (TNSC), soluble sugars (SS), and starch concentrations across cultivars that reportedly differ in biennial bearing tendencies and return bloom potential. Plant material representing 'Grygleski Hybrid 1' ('GH1'), 'Stevens', and 'HyRed' were collected from a commercial cranberry marsh located in central Wisconsin. Concentrations of sucrose, glucose, fructose, and starch were determined via high-performance liquid chromatography. Vegetative uprights generally had greater concentrations of carbohydrates relative to reproductive uprights, while roots had the lowest concentration across all cultivars. Concentrations of TNSC and SS in reproductive uprights were lowest on 30 July 2013, which corresponds to late bloom/early fruit set and terminal bud development. 'Stevens' and 'HyRed' TNSC and SS concentrations subsequently increased after this period, whereas concentrations remained low in 'GH1'. Return bloom potential was lower in 'GH1' relative to 'Stevens' and 'HyRed'. These findings support the explanation that carbohydrate limitation in reproductive uprights may contribute to biennial bearing by reducing the potential for return bloom.