Cold Tolerance of Blueberry Genotypes throughout the Dormant Period from Acclimation to Deacclimation

Authors: Rowland, Lisa; Ogden, Elizabeth; Ehlenfeldt, Mark

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 3/24/2007
Publication Date: 7/1/2007
Citation: Rowland, L.J., Ogden, E.L., Ehlenfeldt, M.K. 2007. Cold Tolerance of Blueberry Genotypes throughout the Dormant Period from Acclimation to Deacclimation. HortScience, v. 42, p. 823

Interpretive Summary:

Technical Abstract: Cold hardiness in woody perennials is determined by complex interacting factors: the timing and rate of cold acclimation; the degree of cold tolerance attained; the maintenance of cold tolerance during the winter; and the rate of loss of cold tolerance or deacclimation upon resumption of spring growth. For highbush blueberry, the degree of winter freezing tolerance and susceptibility to spring frosts have been identified as the most important genetic limitations of current cultivars. Depending on the winter and the location, both can cause damage to floral buds or flowers resulting in substantial losses in yield. In a previous study, in order to identify genotypes that are particularly slow or late to deacclimate and thus may be useful in breeding for spring-frost tolerant cultivars, we compared deacclimation kinetics under field conditions among 12 blueberry genotypes. Clear genotypic differences in timing and rate of deacclimation were found. The species V. constablaei was identified as particularly late to deacclimate, and ‘Little Giant’, a 50:50 hybrid of V. constablaei and V. ashei, was nearly as late to deacclimate as 100% V. constablaei. In a more recent study, we extended our cold tolerance measurements from October through April, comparing acclimation kinetics, maximum cold tolerance, and deacclimation kinetics among seven blueberry genotypes. Although all genotypes appeared to reach maximum cold tolerance about mid-December, genotypic differences were detected in other aspects, including initial cold tolerance, rate of acclimation, maximum cold tolerance, length of the plateau, and rate of deacclimation. Understanding how cold tolerance levels change throughout the dormant period should help us to develop cultivars better suited to their environments.