Evaluation of Dormant Primary Bud Hardiness of Muscadine Grape Cultivars

Abstract

Primary bud hardiness of 11 muscadine grape ( Vitis rotundifolia Michx) cultivars and 'Mars' bunch grape ( V labruscaL.) was evaluated using differential thermal analysis on samples taken in November and December, 1994, and January and February, 1995 from vines growing at the University of Arkansas Fruit Substation, Clarksville. Bud hardiness increased during the sampling period with the lowest mean low temperature exotherms (MLTE) measured in January and February samples. 'Sterling' muscadine was the hardiest cultivar in the first two sample dates. 'Sugargate' muscadine had the lowest MLTE for any cultivar at any date in February, -23.8 °C. Overall, no cultivar exhibited consistently greater hardiness than others over all sample dates, although 'Fry,' 'Loomis and Tara' were consistently the least hardy cultivars in December, January and February. MLTE for 'Mars' were not lower than those for the muscadines at any date, a surprising finding since 'Mars' is considered much hardier than muscadines. Bud hardiness levels for muscadines exceeded what is generally considered the overall minimum temperature for survival of muscadine vines, suggesting that vine components other than buds may limit their hardiness.