PT - JOURNAL ARTICLE AU - Schnabel, Barbara J. AU - Wample, Robert L. TI - Dormancy and Cold Hardiness in <em>Vitis vinifera</em> L. cv. White Riesling as Influenced by Photoperiod and Temperature AID - 10.5344/ajev.1987.38.4.265 DP - 1987 Jan 01 TA - American Journal of Enology and Viticulture PG - 265--272 VI - 38 IP - 4 4099 - http://www.ajevonline.org/content/38/4/265.short 4100 - http://www.ajevonline.org/content/38/4/265.full SO - Am J Enol Vitic.1987 Jan 01; 38 AB - Cold hardiness of Vitis vinifera L. cv. White Riesling was examined using controlled environments to establish the roles of photoperiod and temperature. Field-grown, potted plants were maintained for comparison. Gradually decreasing daylengths, when combined with constant warm temperatures, increased cane hardiness by 0.8°C, while primary bud hardiness was decreased by 2.7°C. Combining constant cool temperatures with gradually decreasing daylengths resulted in an increase in cane and primary bud hardiness of 1.3°C and 0.8°C, respectively. Long photoperiods and gradually decreasing temperatures increased cane and primary bud hardiness by 1.8°C and 1.1°C, respectively. Combining gradually decreasing temperatures and decreasing photoperiods was the most effective and caused increased hardiness of canes by 4.5°C and primary buds by 5.2°C, thus demonstrating a synergistic effect of these environmental factors. Depth of rest induced by these treatments was examined following cold hardiness evaluation. A chilling treatment facilitated the transition from dormancy to active growth.