Abstract Detail

Physiological Section

Cragin, Jacob [1], Shellie, Krista [2], Serpe , Marcelo Daniel [1].

Endodormancy Release in Grapevine Buds: Chilling Requirements and Changes in Cold Hardiness .

Grapevine (Vitis vinifera L.) buds undergo three well-defined phases of dormancy: para-, endo-, and ecodormancy. Transitioning from endo- to ecodormancy requires exposure to cold and dormancy transition is thought to correspond with changes in bud cold hardiness. Cultivar differences in effective chilling temperature doses and their relationship with cold hardiness have not been well characterized. For two widely grown wine grape cultivars that exhibit different dormancy and cold hardiness behavior, Chardonnay and Cabernet Sauvignon, we investigated the effectiveness of a range of chilling temperatures (-8, -5, -3, 0 and 3 °C) on breaking endodormancy. Chilling exposure required for dormancy transition was determined by recording the number of elapsed hours after cold exposure required for 50% of single node cane cuttings to break bud under forcing conditions. Dormancy transition was related to bud cold hardiness by detection of low temperature exotherms using Differential Thermal Analysis. The most effective temperature for breaking endodormancy of Chardonnay was -3 °C, while that of Cabernet Sauvignon was 3 °C. Also, the coldest effective chilling temperature to break endodormancy was lower for Chardonnay than for Cabernet Sauvignon, -5 and -3 °C, respectively. Under field conditions, Chardonnay transitioned from endo- to ecodormancy earlier (mid-October) than Cabernet Sauvignon (late October) and both cultivars reached maximum cold hardiness in mid-winter when buds were ecodormant. For Chardonnay, the lethal temperature for 50% of buds (bud LTE₅₀) at the time of dormancy transition and at mid-winter was -19.2 and -28 °C, respectively. Similarly for Cabernet Sauvignon, bud LTE₅₀ during dormancy transition and at mid-winter was -17.2 and -25.8 °C, respectively. Results indicate that Chardonnay and Cabernet Sauvignon differ in chilling temperature requirements for dormancy transition and in their bud cold hardiness.  However, both cultivars exhibited increasingly greater cold hardiness during ecodormancy.

1 - Boise State University, Biological Sciences, 1910 University Drive, Boise, Idaho, 83725-1515, United States
2 - U.S. Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Unit, 29603 U of I Lane , Parma, ID, 83660, United States

Keywords:
bud dormancy
grapes
chilling requirements
cold hardiness.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PPS007
Abstract ID:256
Candidate for Awards:None