M.S. Exit Seminar

Nov 20, 2014, 10:00am - 11:00am

M.S.  Exit Seminar

Shouxin Li,
M.S. Student

Advisor: Dr. Imed Dami
Committee:
Dr. Michelle Jones, Dr. Joshua Blakeslee

 

Evaluation and Improvement of Freezing Tolerance in Sensitive Grape Genotypes 

Abstract

Grape and wine industries in colder regions such as Ohio have been expanding rapidly and demand for premium wine grapes has also increased. However, several popular cultivars are sensitive to freezing temperatures below -20°C. The objectives of this research are to: 1) evaluate the freezing tolerance of field-grown winegrape cultivars new to Ohio, 2) evaluate the response of field-grown winegrape cultivars to exogenous ABA, and 3) characterize the changes of freezing tolerance, water content, and soluble sugars in bud tissues of greenhouse-grown grapevines in response to exogenous ABA. Initially, freezing tolerance (or LT50) of 23 cultivars were evaluated between September and April in two locations for two seasons. The purpose of this study was to characterize FT as influenced by genotype. Specifically, the objective of this three-year study was to determine the FT of 23 winegrape cultivars. Three different methods including date-mode method, piecewise regression and mean LT50s were used to estimate FT. Among the 23 cultivars, we were able to divide them into three groups: most cold sensitive including Gamay noir, Pinotage, Rotberger, Regent, Chardonnay, and  Cabernet franc; least cold sensitive including Syrah, Lagrein, Tempranilllo, Barbera, and Durif and the intermediate group  which includes Malvasia, Dolcetto, Siegerrebe, Carménère, Cabernet Sauvignon, Sauvignon blanc, Malbec, Arneis, Teroldego, Sangiovese, Merlot, and Kerner. In the ABA study, we evaluated the effect of exogenous ABA on FT of two cold sensitive cultivars, Vitis vinifera ‘Chardonnay’ and ‘Pinot gris’. Grapevines were treated with a foliar application of ABA at a concentration of 0 mg·L-1 (control), and 400 mg·L-1 ABA at vine phenological stages corresponding to véraison, post-véraison, and post-harvest. Exogenous ABA application at the concentration of 400 mg·L-1 and 500 mg·L-1effectively improved the bud FT of ‘Chardonnay’ and ‘Pinot gris’ without affecting vine size, yield or fruit composition. The best time to spray ABA on ‘Pinot gris’ was between véraison and 20 days post-véraison or leaf age between 105 and 120 which led to the lowest LT50 and deepest dormancy. Differences among ABA application timing of ‘Chardonnay’ were not obvious. Finally, the relationship between sugar metabolism and ABA-induced desiccation was investigated in a temporal experiment to investigate whether ABA induces sugar accumulation and if so when. The purpose of this study was to confirm findings from previous greenhouse experiments. Furthermore, we aimed to determine physiological (tissue water content) and biochemical (tissue soluble sugars) changes in ABA-treated vines. ‘Cabernet franc’ potted grapevines were used in three experiments conducted in the greenhouse in 2012 and 2013. The effects of ABA on FT, water content and soluble sugars in bud and leaf tissues were determined. The results demonstrated that application of exogenous ABA increased the bud FT of greenhouse-grown ‘Cabernet franc’ grapevines and the effect was shown 1w after ABA application. ABA caused bud desiccation, which may have led to increased FT.  Our study shows that bud dehydration may occur as early as 48h after ABA application which led to increased FT (decreased LT50) one week later. Ultimately, the findings of this project are valuable to grape producers to provide another tool for freeze protection and to the scientific community to further our understanding of the mechanisms of freeze tolerance.

Thursday November 20th, 2014
10.00 AM – 11.00 AM

130 Research Service (Wooster)
video linked to
202F Kottman (Columbus)