Evaluating the effects of vineyard management strategies on cold stress in wine grapes

Restricted (Penn State Only)
Author:
Smith, Maria Suk
Graduate Program:
Horticulture
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
August 06, 2018
Committee Members:
  • Michela Centinari, Dissertation Advisor
  • Richard Marini, Committee Chair
  • Kathleen Kelley, Committee Member
  • Ryan Elias, Committee Member
  • Ryan Elias, Outside Member
Keywords:
  • Viticulture
  • Cold stress
  • Freeze injury
  • Canopy management
  • Cultivar selection
  • Hydraulic transport
  • Anatomy
  • Crop load
  • Cluster thinning
  • Early leaf removal
Abstract:
Cold stress is among the major limiting factors for wine grape production in Pennsylvania. Post-budburst spring frost events and dormant mid-winter low temperatures can cause freeze injury of grapevine vegetative and reproductive tissues resulting in partial or total crop loss. Vineyard management practices, such as site and cultivar selection and crop load management, can impact vine susceptibility to freeze stress through avoidance or tolerance mechanisms. To understand how different practices influence vine susceptibility to freeze injury, it is crucial to analyze plant physiological adaptation and response mechanisms. Three studies utilizing young potted vines grown outdoor and mature vineyard plantings were conducted to evaluate the role of cultivar selection and crop load management in reducing the risk of freeze injury during the dormant season or post-budburst. Each study evaluated different aspects of vineyard practices and the relationship to freeze injury. In the first study, two Vitis species with different genetic parentage and mid-winter freeze tolerance were compared for hydraulic response and recovery to post-budburst freeze injury. Stem xylem anatomical traits of each species were measured to determine their role in vine response and recovery to freeze injury. The second and third studies compared a novel crop load management technique, early leaf removal (ELR), to a more traditional yield regulation practice, cluster thinning (CT), on two high-yielding cultivars, Vitis hybrid Chancellor and V. vinifera Grüner Veltliner. In each of these two studies, the timing (Grüner Veltliner; trace bloom versus fruit set) and intensity (Chancellor; low versus high) of ELR and CT were compared to an un-defoliated, un-thinned control. One of the objectives was to understand how manipulating vine crop load (i.e., carbohydrate source-sink ratio) would influence leaf photosynthetic capacity (Grüner Veltliner) and overwinter starch concentration in storage tissues (Chancellor) and how those factors relate to bud winter freeze tolerance. Additionally, the impact of crop load management practices on commercially important production parameters, such yield components, fruit ripeness, wine composition and consumer sensory perception (Chancellor), and economic impacts were assessed. In the first study, short-term hydraulic response (within 48 hours) to a temperature-controlled post-budburst freeze stress differed by species. Species differences in stem xylem anatomical traits (e.g., vessel frequency, vessel grouping) supported the contrasting hydraulic response. The long-term seasonal recovery from freeze injury, however, was similar between species despite differences in anatomical traits. In the second and third study, ELR had a greater impact on bud freeze tolerance than CT only during vine acclimation in Grüner Veltliner and during mid-winter in Chancellor; however, all crop load treatments positively influence starch concentration in perennial tissues. Furthermore, the vine response to ELR depended on the percentage of leaf area removed, which was higher in Chancellor than Grüner Veltliner at the same phenological stage. Overall, our results pertaining to freeze injury suggest a continued need for exploring mechanisms behind vine response to vineyard management practices and vine traits that benefit response and recovery to cold stress.