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Evaluation of Freezing Tolerance of Three Asparagus officinalis L. Cultivars during Fall Cold Acclimation and Spring Dormancy Release in Southern Ontario

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Title: Evaluation of Freezing Tolerance of Three Asparagus officinalis L. Cultivars during Fall Cold Acclimation and Spring Dormancy Release in Southern Ontario
Author: Panjtandoust, Mahmoud
Department: Department of Plant Agriculture
Program: Plant Agriculture
Advisor: Wolyn, David
Abstract: Winter hardiness is necessary for asparagus cultivars grown in southern Ontario and requires establishment of dormancy in the fall before freezing, and maintenance of dormancy during the winter and freeze-thaw cycles of spring. In a field study, quantitative assessment of freezing tolerance for Guelph Millennium (GM), Jersey Giant (JG), and UC 157 (UC) indicated differences over four sampling dates during the fall, early-October to mid-November, and spring, the month following soil thawing. High freezing tolerance generally correlated with high low-molecular-weight fructan (LF), protein and proline, and low sucrose concentrations in the rhizome, and high sucrose and proline, and low LF concentrations in the storage roots. GM, with the highest freezing tolerance, became dormant early in the fall and maintained bud dormancy late in the spring. The timing of dormancy release, or spear emergence, differed among cultivars in a pot experiment examining different durations of exposure to chilling and freezing temperatures. GM emerged later than the two other cultivars under both freezing and chilling treatments at most durations, suggesting its superior field longevity may be due, in part, to the maintenance of freezing tolerance during freeze/thaw cycles of the spring. Delay in spring dormancy release as well as timely dormancy induction in the fall can be important asparagus breeding traits in areas with cold winters.
URI: http://hdl.handle.net/10214/9788
Date: 2016-05


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