Sensitivity of northern highbush blueberry cultivars to soil water deficits during various stages of fruit development

Authors: ALMUTAIRI, KHALID - Oregon State University; Bryla, David; STRIK, BERNADINE - Oregon State University

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2020
Publication Date: 2/1/2021
Citation: Almutairi, K.F., Bryla, D.R., Strik, B.C. 2021. Sensitivity of northern highbush blueberry cultivars to soil water deficits during various stages of fruit development. HortScience. 56(2):154-162. https://doi.org/10.21273/HORTSCI15493-20.
DOI: https://doi.org/10.21273/HORTSCI15493-20

Interpretive Summary: Water limitations are increasing in many regions because of drought and competition for water resources, and growers must often decide when to limit irrigation during drier years. To identify periods in which irrigation may be less critical for blueberries, an ARS researcher in Corvallis, OR and collaborators from Oregon State University evaluated the effects of soil water deficits during fruit development in a wide range of blueberry cultivars that ripen at various times between late June and early September. As a rule, short, 2-week periods of water deficit during various stages of berry development had little to no effect on yield but reduced the firmness of the berries in most of the cultivars, as well as berry weight in several cultivars. Predictably, water deficits applied during later stages of fruit development had the largest effects, particularly in mid- and late-season cultivars, which ripened primarily in July and August during the warmest and driest months of the year. Thus, growers should pay close attention to irrigation in these cultivars and, if possible, apply water at least every 2–3 d during this time of year. On the other hand, irrigation was less critical during early stages of fruit development, suggesting this might be a good time to reduce irrigation if needed. Results from the study will help blueberry growers increase the efficiency of irrigation water use and reduce losses of yield and fruit quality when facing water limitations in drier years.

Technical Abstract: Water limitations are increasing in various regions because of drought and competition for water resources, and many growers, including those producing blueberries, must decide when to limit irrigation during drier years. Thus, to identify periods in which irrigation may be less critical, we evaluated the effects of soil water deficits during fruit development for 2 years in western Oregon on five cultivars of northern highbush blueberry (Vaccinium corymbosum L.). The cultivars in order of ripening included ‘Earliblue’, ‘Duke’, ‘Bluecrop’, ‘Elliott’, and ‘Aurora’. The exact stage that soil water deficits were applied varied but, in each cultivar, ranged from the early green stage to the 10% blue stage of fruit development. Volumetric soil water content and stem water potentials declined within a week or two with no rain or irrigation, particularly during the later stages of fruit development (late-green to blue). Water deficits only reduced yield in ‘Aurora’, which produced less fruit when water was withheld immediately prior to harvest, but affected berry weight in three cultivars, including ‘Earliblue’, ‘Elliott’, and ‘Aurora’, where, relative to fully irrigated controls, was lower in one or both years of the study when irrigation was withheld during early or late stages of fruit development. In many cases, water deficits also reduced fruit firmness and increased the concentration of soluble solids in the berries. However, it had inconsistent effects on titratable acidity and sugar-to-acid ratios in the berries. As a rule, water deficits were most detrimental during later stages of fruit development, particularly in mid- and late-season cultivars, which ripened during the warmest and driest months of the year in July and August.