Preliminary evaluation of northern highbush blueberry for heat tolerance in Oregon and Washington

Authors: ANDERSON, TODD - Oregon State University; HUMMER, KIM - Retired ARS Employee; LUBY, CLAIRE - Montana State University; Bassil, Nahla

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 5/3/2023
Publication Date: 8/3/2023
Citation: Anderson, T., Hummer, K., Luby, C., Bassil, N.V. 2023. Preliminary evaluation of northern highbush blueberry for heat tolerance in Oregon and Washington. HortScience.

Interpretive Summary:

Technical Abstract: Northern highbush blueberries (NHB, Vaccinium corymbosum L.) are a high-value, heat-sensitive fruit crop important in the Pacific Northwest. The region is experiencing increased extreme heat events that decimate sensitive crops. This trend is expected to continue, threatening the blueberry industry. Recently, blueberry production in Oregon and Washington's hot summer valleys east of the Cascades has expanded rapidly. Many blueberry cultivars in production respond poorly to these high-heat events and the more extreme conditions. To better support growers, the United States Department of Agriculture - Agricultural Research Service (USDA-ARS)/Oregon State University Collaborative Breeding Program is working to understand heat tolerance and develop blueberry cultivars that are more tolerant to extreme heat. Six NHB cultivars with differing observed heat tolerance were crossed, resulting in 15 breeding families of NHB. These progeny, the six NHB parents and two rabbiteye (Vaccinium virgatum) cultivars were planted at four sites in the Pacific Northwest. For this study, the breeding program chose two areas representing established blueberry production regions with mild growing seasons west of the Cascade Mountains in Corvallis, Oregon, and Lynden, Washington. In addition, two sites were selected to represent areas with more extreme summer temperatures: Myrtle Creek, Oregon, and Prosser, Washington. The objectives of this work were to: 1) identify plants with tolerance to high heat conditions; 2) phenotype traits indicating tolerance or susceptibility to high heat events and determine the heritability of these traits; and 3) gain an understanding of the best trialing location to assess heat tolerance in future trials of potential cultivars. In 2021 and 2022, we measured phenotypic traits associated with heat damage to fruit and foliage, including fruit sunburn, fruit texture, ° Brix, acidity, desiccation of new growth, and death of mature foliage. We observed different environmental conditions during the study period. In our first year of data collection, 2021, a heat dome occurred during the early and mid-ripening process of blueberry fruits, affecting all four locations. We monitored fruit size, weight, texture, foliar tip burn, leaf scorch, and fruit sunburn at the four trial locations. We will report our findings concerning elite breeding families, individuals, cultivars, and potential breeding combinations with greater tolerance to heat damage than the current commercial NHB parents.