PROSSER, Wash. – In much of Europe, it is illegal to irrigate wine grapes after veraison – the change of color indicating ripening – for fear of diluting brix, or sugar content. But recent research is calling into question this taboo, especially for semiarid regions like eastern Washington – and Spain.
In fact, a visiting scientist from Spain, Pascual Romero, is working for a year at WSU’s Irrigated Agriculture Research and Extension Center at Prosser to better understand irrigation management in vineyards.
Romero is the lead author of the 2010 Best Paper in Viticulture award from the American Journal of Enology and Viticulture.
The subject of the paper, deficit irrigation, highlights new understanding of how irrigation affects the physiology of grapevines.
Recent research by Chateau Ste. Michelle Distinguished Professor of Viticulture Markus Keller and others at Prosser has shown that late-season irrigation does not dilute brix and, if done correctly, accelerates ripening.
“That said, we need lots more research on the effects of irrigation on grapevine physiology,” Keller said.
Romero and his colleagues’ paper begins to address that need. Building on research conducted by Keller and many others, the Spanish scientists found that regulated deficit irrigation (RDI) requires a thorough understanding of “several threshold values for plant stress indicators.”
Better knowledge of the contribution of late-season irrigation and water stress to variations in berry size and fruit quality will lay the foundation for better vineyard irrigation management. In semiarid regions, that is crucial information because water use affects producers’ economic bottom line.
“During my year at WSU, my main goal is to learn more about grapevine water relations … and deficit irrigation in this dry climate,” Romero said. “I want to study the techniques, tools and approaches used in Keller’s lab to measure the vines’ responses to water deficit.”
In addition, Romero will participate in ongoing irrigation research in collaboration with Keller’s graduate students, WSU enologist Jim Harbertson and researchers at Ste. Michelle Wine Estates, which seeks to fine-tune deficit irrigation in order to maximize fruit and wine quality.
Romero said that another goal is to initiate collaborative research between Washington and Spain.