Posts Tagged: enology
Findings could help wine industry adapt to climate change
Scientists at UC Davis have identified new root traits that help grapevines resist drought. The findings, published in the journal Annals of Botany, could speed up the development of grape rootstocks that protect vines from dry conditions, helping the grape and wine industry adapt to climate change.
The research, led by Department of Viticulture and Enology Assistant Professor Megan Bartlett, comes as 80% of California is experiencing extreme drought.
Most grapevines are not rooted directly into the ground but are instead grafted onto a rootstock, which forms the underground part of the plant and supports growth above ground.
“Rootstocks are an important tool to manage water stress,” Bartlett said. “Our goal was to identify traits that make rootstocks drought tolerant, so that grape breeders can amplify these traits in new varieties.”
Root cell traits
The study focused on traits measuring drought responses in living root cells.
The research specifically identified capacitance – which measures how much roots shrink as they dehydrate – as an important trait for drought tolerance.
“The water that enters the roots has to cross through a band of living cells to reach the xylem – the network of pipes that carries water up to the leaves,” said Bartlett. Most research has focused on xylem traits, but the living cells are often the first to be damaged during drought.
Water stress can shrink, deform, or even kill the living cells, causing the roots to shrivel away from the soil and lose access to the remaining soil water. Vines are then unable to replace water lost to evaporation and are forced to close the stomata – the small pores on the leaves that take in carbon dioxide for photosynthesis – to prevent severe dehydration. But closing the stomata stops photosynthesis and starves the vine of the sugars it needs to grow and ripen fruit.
This study is the first to test whether traits measuring root shrinkage and cell collapse can capture differences in rootstock drought tolerance.
Cell traits and drought tolerance
The researchers grafted Chardonnay onto eight commercial rootstocks. Half of the vines experienced drought conditions and half were kept well-watered in a greenhouse experiment.
The study found the eight rootstocks were surprisingly diverse and varied widely in their traits. The rootstocks also appeared to acclimate to drought by changing their traits in that the droughted vines were less susceptible to shrinkage and cell collapse than the well-watered vines.
Among the traits, capacitance was especially important for drought tolerance. The rootstocks with a lower capacitance (less root shrinkage) were better able to maintain photosynthesis during drought than other rootstocks.
“This research gives us a new trait to target for breeding more drought tolerant rootstocks,” study co-author and Ph.D. student Gabriela Sinclair said.
The research was supported by the American Vineyard Foundation, UC Davis, and by donations to the department from the Rossi family. Researchers at the University of British Columbia and the USDA-ARS Crops Pathology and Genetics Research Unit also contributed to the study./h3>/h3>/h2>
Ten large, shiny tanks stand near the Robert Mondavi Institute for Wine and Food Science at UC Davis, holding more than a year of rainwater and the key to processing food and drink during a drought. The water tanks, and the teaching-and-research winery they support, are showing students and winemakers throughout the world how to reduce processing costs, improve wine quality, and protect the planet's dwindling natural resources.
The work is the latest in more than a century of trail-blazing viticulture and enology science at UC Davis. UC Davis researchers are working with Cooperative Extension specialists and farm advisors with UC Agriculture and Natural Resources to help winemakers and grape growers sustainably produce premium wine.
Water is critical to winemakers in drought-stricken California and beyond. Grapes aren't a very thirsty crop to grow, but keeping fermentors clean is another story.
A typical winery uses four to six gallons of water after the grapes are harvested to produce one gallon of wine, and most of that water is used to wash equipment. Boulton and David Block, chair of the UC Davis Department of Viticulture and Enology, are developing self-cleaning fermentors capable of recycling 90 percent of that water. The goal: affordable technology and alternative practices that use less than one gallon of water to produce one gallon of wine.
Winemakers currently remove sticky, fermented, grape residue from tanks with water and elbow grease. Clean-in-place technology replaces hand-cleaning with an automated system that sprays tanks with diluted solutions of potassium hydroxide and potassium bisulfate.
“The dairy industry has used clean-in-place technology since the 1960s and the pharmaceutical industry since the 1990s,” says Block, a chemical engineer and enologist who helped the pharmaceutical industry manage clean-in-place technology before coming to UC Davis in 2008. “It's a little different with dairy and pharmaceuticals, where poor sanitation can kill you, but the concept is similar.”
“We will filter and reuse that water at least five times, hopefully one day up to 10 times,” Boulton says. “It's not waste water. It has no phosphates, no nitrates, and no chlorine. Clean-in-place technology represents a huge potential for water and labor savings.”
Industry is starting to notice.
“Clean-in-place technology is very attractive to us,” says Ashley Heisey, director of winemaking at Long Meadow Ranch in Rutherford and a UC Davis viticulture and enology graduate. “Water is such a critical issue. Long Meadow Ranch owners Ted, Chris, and Laddie Hall built our facilities with great concern for the environment, and thanks to UC Davis, we can take it one step further.”
In Sacramento, grocer Darrell Corti from Corti Brothers Market says where UC Davis leads, winemakers will eventually follow.
“What we know about grape-growing and winemaking is primarily due to the work they do at UC Davis,” Corti says.
A longer version of this story is in the magazine Edible Sacramento.
Not until students turn 21 can they taste the wine and beer they make and learn to assess its sensory quality. Learning the characteristics of a wide assortment of good (and not-so-good) wines and beers is an important component of winemaking and brewing. Having to wait until their junior or senior year to learn these skills is a disadvantage for these students.
Legislation (AB 1989) has been proposed by California Assemblyman Wesley Chesbro (D-North Coast) that will allow students, ages 18 to 21, enrolled in winemaking and brewery science programs to taste alcoholic beverages in qualified academic institutions. The students can taste, but not consume — which means they must learn the professional practice of spitting during the tasting process.
“Winemakers taste wine daily during harvest to quickly make critical decisions as the winemaking is underway,” Waterhouse said. “Our students need to start learning this skill here, with our guidance. And, they also have to get over the embarrassment of spitting — after every taste.”
Chik Brenneman, the UC Davis winemaker, said that the bill, if passed, “will allow students to move on to the sensory program a lot sooner, before they've finished most of their winemaking classes. Earlier sensory training will help them when they go to work in the industry.”
If the legislation passes, it will benefit enology and brewing students at UC Davis, which is the only University of California campus to offer undergraduate degrees in viticulture and enology and in brewing science (an option within the food science major).
While parents of college students may worry that the bill will open the door to widespread drinking, Waterhouse and Brenneman both noted that the focus of the bill is so narrow that its impact will benefit a limited number of students, and that it's unlikely to lead to excessive drinking. They say that the over-21 students routinely spit what they're tasting in a standard industry manner, and that “drinking” in class is not a problem.
With passage of this bill, which is backed by the University of California, the state will join 12 other states that have allowed this educational exemption for students.
- California legislative information on AB 1989
- NBC Bay Area: Reality check: Bill calls for underage tasting on college campuses, Feb. 27, 2014
- Bill by Wes Chesbro would allow underage beverage students to sip; PressDemocrat.com, Feb. 28, 2014