Kearney, Anne A., authorCaspari, Horst, advisorMenke, Stephen, advisorStromberger, Mary, committee memberWallner, Stephen, committee member2015-08-282015-08-282015http://hdl.handle.net/10217/167237There is a lack of economic sustainability on the increasingly popular cold-sensitive Vitis vinifera cultivars due to cold damage, resulting in very low crop yields. Recent research to improve the cold hardiness of these cultivars to keep up with demands has shown that cold hardiness of grapevine buds can be increased through foliar applications of abscisic acid (ABA) and urea. Therefore, five different ABA treatments at 400 mg L⁻¹ each and one treatment of 40 g L⁻¹ urea were evaluated on Chardonnay and Syrah vines growing at the Western Colorado Research Center in Grand Junction, CO. The treatments were: veraison (V) which was applied at 50-75% veraison, 20 days post-veraison (V20), 40 days post-veraison (V40), double treatments at veraison plus 20 or 40 days post-veraison (V + V20 and V + V40, respectively) and a late season urea treatment. The treatments were evaluated against a control of 0.05% surfactant and water in Chardonnay and Syrah grapes. V and V20 were also evaluated against a control in Merlot and Cabernet Franc. Compound dormant buds were sampled monthly and primary bud survival was assessed. In the early part of the acclimation process, V, V20, V40, and V + V20 treatments showed significant improvements in bud cold hardiness Chardonnay and Syrah, as well as in Cabernet Franc. Bud cold hardiness was unaffected across all treatments in Merlot early on all the way past mid-winter. While no significant difference was detected after October between treatments and bud survivability compared to the control in all varieties, a few treatments showed positive significant differences from month to month. Yield and basic fruit components were not affected. However, anthocyanin accumulation was significantly greatest in the V20 group for Cabernet Franc. Foliar applications of abscisic acid show potential as future cold hardiness methods and should be evaluated further over several growing seasons for potential prolonged increases in bud cold hardiness.born digitalmasters thesesengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Text