Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2000
Publication Date: 2/1/2001
Citation: Sampson, B.J., Noffsinger, S.L., Gupton, C.L., Magee, J.B. 2001. Pollination biology of the muscadine grape, vitis rotundifolia michx. HortScience. 36(1) :120-124.2001
Interpretive Summary: The muscadine grape has for almost four centuries been a source of uniquely flavored fruit and wine in the American South. Uncultivated ancestors of today's muscadine varieties have separate sexes, ensuring that vines produce progeny having superior alleles. These wild vines clearly rely on insects to carry the pollen from male to female flowers before any berries are set. The many different flower types exhibited by modern muscadine cultivars (e.g. male, female and bisexual flowers) have obscured this simple mutual relationship between the vine and the insect pollinator. Self-pollination and wind cross-pollination are generally thought to be the more efficient pathways for grape pollination. However, fruit set by the cultivated muscadine is reliant on, or in some measure benefits from insect cross- pollination. Therefore, satisfactory berry set for the muscadine grape hinges on maintaining efficient pollination by indigenous insects, especially sweat bees.
Technical Abstract: Fruit set for the muscadine grape, vitis rotundifolia Michx., mostly depended on insect cross-pollination, although flowers were also well adapted for selling. Pollinizer cultivars produced about half of their optimal fruit set strictly by selfing, but cross-pollination was needed to reach an optimal fruit set of 33.7% at our research vineyard. Eighty-one percent of the overall fruit set by pistillate vines was attributed to insect cross-pollination. Wind played a small role in vineyard cross-pollination. Diminished fruit set and fewer seeds per berry were also detected for the muscadine cultivars receiving no effective cross-pollination. Components of fruit quality were not profoundly affected by the pollination treatments, although seed set and berry weight for pistillate vines responded negatively to an absence of cross-pollination. Parthenocarpy was rare, except for 'Fry Seedless' a seedless cultivar. Muscadine production throughout the southeastern United States clearly depends on cross-pollination by indigenous insects, particularly bees. Preserving bee nesting sites, and providing bees with safe access to muscadine flowers are essential to ensure consistently high yields.