Effect of Site on Cold acclimation And Deacclimation of Concord Grapevines

Abstract

The effect of site on cold hardiness of <i>Vitis labruscana</i> Bailey 9Concord9 grapevines was investigated in southwestern Michigan. Air temperatures were consistently lower for a poorly air-drained low site than for a nearby well-air-drained high site. Seasonal hardiness changes followed seasonal changes in air temperature. Canes acclimated faster and to a greater degree of hardiness on low site vines than on high site vines. Both site and compound (primary vs. secondary shoot primordia) bud differences were important in determining bud hardiness. High site buds tended to be less hardy than low site buds. Early spring deacclimation status indicated that bud hardiness differences were due to site-induced differences in air temperature, while inherent differences between the primary and secondary bud were solely responsible for differences in late spring bud hardiness. The two sites generated distinct temperature-induced microclimates where differences in vine adaption were possible. Site induced air temperature and bud differences appeared to interact to influence cold hardiness of Concord grapevines during acclimation and deacclimation. Concord grapevines apparently adapted to lower fall, winter, and spring air temperatures through exposure.