330 VACCINIUM ANGUSTIFOLIUM POPULATION VARIATION IN LOW-TEMPERATURE TOLERANCE AND FLOWERING CHARACTERISTICS

Commercial lowbush blueberry production involves management of what have long been considered highly diverse populations of naturally occurring clones. Wide phenotypic variation evident in fields has often been anecdotally equated with variation in yield, cultural requirements, etc., however this has not been tested rigorously. Interest in selection of clones with superior low-temperature tolerance prompted this study to estimate population-wide variation within the species. Thirty six clones of Vacciniun angustifolium exhibiting most of the typical phenotypic classes were selected from two commercial production fields in Maine. Plants were evaluated for low-temperature tolerance of reproductive and vascular tissues on a monthly basis from November through April. In addition, variation in relative time of anthesis, flower structure, and floral low-temperature tolerance were determined. Results are discussed with respect to potential for selection of superior clones for both fruit production and ornamental use.