Michael Cook, a viticulturist with Texas A&M AgriLife Extension Service, jokes about the summertime weather in Dallas-Fort Worth: “What’s the difference between day and night? Nothing. The lights go out.” North Texas, like the Texas Hill Country and the Gulf Coast, is a viticultural region that lacks a diurnal shift, a climatic feature that gives grapevines and other plants a chance to cool down at night. However, despite such challenges, viticulture is not only present in North Texas, but in a state of maturation and refinement.
Grapevines—and all horticultural crops—are contending not only with more heat stress during the growing season, but unpredictable and extreme changes in temperature. This is why Amit Dhingra, Ph.D., the head of the department of horticultural sciences at Texas A&M University, emphasizes the term “climate resilience,” rather than simply climate change. The issue of climate resilience transcends Texas.
For example, Frédéric Panaïotis, the chef de caves at Ruinart in Champagne, recalls harvesting at his grandparents’ vineyard in the 1980s, “hands frozen and eating warm sausages at 10 in the morning.” Three years ago, Ruinart began tracking temperature, sunshine hours, rainfall, and growing cycles, establishing that today’s annual temperature is elevated from historic norms by roughly 1.3 degrees Celsius, which means a loss of 10 to 12 days in the growing season.
Dr. Dhingra explains that plants already have some ability to acclimate to higher than normal temperature conditions by revisiting the image of a frog in boiling water; in 19th-century experiments, if the temperature increased slowly, the frog did not attempt to escape the water. “When you have persistent heat, the plant becomes accustomed and can survive that quite a bit,” he explains. “It’s extreme events that cause damage quickly, like the burning of leaves and complete drying, because the plant doesn’t get to engage mechanisms that can conquer some of the challenges.”
Given that extreme changes in temperature can damage grapevines and other plants before they can prepare themselves for survival, plants have no choice but to become more resilient, but how much heat and unpredictability can they tolerate?
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