Climate change may confuse plant dormancy cycles

Perennial plants in the Midwest are well attuned to their surroundings. They hunker down all winter in a dormant state, just waiting for a sign that it’s safe to unfurl their first tender leaves or flower buds. For many plants, the cue is a sustained warming trend, but day length also factors into the dormancy equation.

Day length is governed by our trip around the sun each year – that’s set in stone – but unusual temperature fluctuations are becoming more common as our climate is changing. So what happens to perennials when the sun tells them they should stay dormant, but warming soil tells them another story? A new study from the University of Illinois has some answers.   

Switchgrass and prairie cordgrass, both native perennial grasses grown for biomass, come out of dormancy when the soil warms up for a week or more, usually in April. As temperatures rise, stored carbohydrates in the plants’ rhizomes are converted into mobile forms to fuel growing tissues. If this happens during an unusually early thaw, new shoots could be killed and rhizomes could be left depleted when temperatures return to their normal range. The plant may not have enough oomph to produce new shoots later in spring, affecting biomass yield in agronomic settings or competitive ability in natural plant communities. 

To look at the interplay between soil temperature, day length, and dormancy in switchgrass and prairie cordgrass, D.K. Lee and his collaborators designed a study to trick the plants.

Read more at University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES)

Image: D.K. Lee with switchgrass. (Credit: Image courtesy of University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES))