Physiological Mechanisms Associated with Cold Deacclimation Sensitivity of Cool-Season Grasses.

Increases in soil and air soil temperatures during the overwintering period may trigger metabolic and physiological changes leading to cold deacclimation and loss of freezing tolerance in cool-season turfgrasses. Elevated temperatures followed by freezing events can result in increased sensitivity of grasses to direct low temperature kill, particularly for species such as annual bluegrass (Poa annua L) and perennial ryegrass (Lolium perenne L.).   Results will be presented to summarize research evaluating mechanisms associated with deacclimation in selected cool-season grasses contrasting in freezing tolerance and deacclimation sensitivity, including changes in gene expression, hormone regulation, and carbon and nitrogen metabolism.