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Evaluation of Spring Frost Control Methods and an Assessment of Cold Hardiness in Cranberry (Vaccinium macrocarporn Ait.)

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Abstract
The American cranberry (Vaccinium macrocarpon Ait.) is an important temperate woody shrub crop whose fruit has human health benefits. Cranberry acquires cold hardiness in the autumn and loses it in spring, following deacclimation. Frost protection is necessary in cranberry production as a means to reduce bud damage due to low spring temperatures. The objectives of the field studies were to evaluate two methods of sprinkler irrigation for frost protection, the conventional approach consisting of continuous irrigation throughout the night (CON) and intermittent cycling of sprinklers (INT) incorporating cycling on and off throughout the night, by (i) assessing bud damage and yield for cranberry cultivars 'Early Black', 'Howes', and 'Stevens' managed under both methods and (ii) to determine the volume of water used in each method. The objectives of the laboratory studies were to (i) evaluate and quantify carbohydrates and lipids synthesized by cranberry during the cold acclimation period under a controlled environment and to (ii) determine the cold hardiness (LT50) and lowest survival temperature (LST) of buds of economically important cranberry cultivars during acclimation. For INT to be an effective frost control method, temperature set points should be cultivar specific. Despite differences in bud damage, cranberry yield data did not show any significant differences between the two frost management methods. Since cranberry plants produce more flowers than the number of set fruit that can be supported, the remaining flowers in damaged buds may have been sufficient to produce similar yields in both methods. Substantial water savings were obtained under INT, especially on mild frost nights. Greater concentrations of total non-structural carbohydrates (TNSC) and membrane stabilizing lipids and a higher fatty acid unsaturation index were associated with low acclimation temperatures. This result suggests the importance of these compounds in increasing cold hardiness in cranberry during acclimation. In addition, a progression of freezing tolerance, determined as the LT50 and LST, was noted in the fall for all the cranberry cultivars. Knowledge of bud hardiness in the fall is important in considering the need to protect buds. Differences in hardiness should be considered when implementing frost protection in the fall.
Type
dissertation
Date
2015-09
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