Page 22 - CSHS 2022 Book of Abstracts - 2022-08-22 web version

CSHS 2022 Conference

(FO.5) Impact of crop load management on terpene concentration of Gewürztraminer grapes in
the Okanagan Valley
Yevgen Kovalenko, Joshua VanderWeide, Ricco Tindjau, Simone Castellarin*
Wine Research Centre, Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC
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Crop load management by cluster thinning can improve ripening and the concentrations of key metabolites for
grape and wine quality. Timing and degree of cluster thinning are known to alter the effectiveness of the treatment.
However, little work has been done on the impact of crop load management via cluster thinning on terpene content
in white grapes. In a 3-year field study conducted in the Okanagan Valley (Oliver, B.C.) cluster thinning was applied
to Gewürztraminer vines at two developmental stages: after fruit-set (Early Thinning) and at veraison (Late
Thinning). Reducing yield by 40% in the vineyards via cluster thinning applied early in the season (Early Thinning)
accelerated ripening as determined by faster sugar and terpene accumulation. In addition to observing the
acceleration of ripening by early cluster thinning, it was demonstrated that cluster thinning applied at veraison had
neutral to negative effects on terpene accumulation. Geraniol and total terpenes accumulated more rapidly with
Early Thinning, however, at harvest, individual terpenes and total terpenes were similar among treatments. This
study shows that late applications (mid-season) are ineffective for the terpene content. On the contrary, early cluster
thinning allows growers to accelerate ripening and terpene accumulation and harvest grapes earlier, which is useful
in viticultural regions where the climate does not allow a late harvest as often occurs in Canadian wine regions.

(FO.6) Patterns of freezing injury in spring-grown woody-fruiting perennials
Ian R. Willick , Laurence V. Gusta , Karen K. Tanino
1*
2
2
1. AAFC, Kentville, NS; 2. Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK
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As buds swell in the spring, they become increasingly susceptible to freezing injury. This can result in significant
yield penalties. We applied infrared video thermography to evaluate the pattern of latent heat released during an
exothermic freezing event and the degree of injury in flowers and vegetative tissues of haskap (Lonicera caerulea L.),
black currant (Ribes nigrum L.) and Saskatoon serviceberry (Amelanchier alnifolia Nutt.). Contrary to the historically
hypothesized patterns of freezing, ice nucleation initiated from the woody stem tissues and not the uppermost
leaves in the cutting. The proximity of a leaf to an ice nucleation event in the woody stem tissue influenced the order
of freezing. Freezing progressed through two exothermic events. An initial rapid exotherm developed around -3.6 ±
0.5°C and lasted within a tissue for up to 10 s. A second exotherm propagated through the tissue in 1 to 4 min. Lethal
injury in flowers and leaves occurred up to an hour after the completion of the second exotherm. While this third
stage of freezing was not detectable by infrared video thermography, it was indirectly determined by electrolyte
leakage analysis. Spring-grown black currant were the most freezing tolerant (-9.5 ± 0.5°C), followed by wild haskap
(-5.8 ± 0.5°C), Saskatoons (-5.5 ± 0.4°C), and cultivated haskap (-4.7 ± 0.3°C). These results underscore the
complexity of the freezing process in woody perennial fruiting crops and indicate that comprehensive observational
studies are essential to identify and select freezing tolerant traits.

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