- Author: Jeannette E. Warnert
“We’ve had some very severe frosts in San Luis Obispo County and on the Central Coast over the years,” said Mark Battany, UC Cooperative Extension advisor in San Luis Obispo and Santa Barbara counties. “In 2011 we had the most severe frost in 30 years and many millions of dollars of crop and wine value were lost because of that freeze.”
Farmers take various measures to protect their crops when temperatures dip below freezing, such as mowing or tilling the vineyard row middles, or running sprinklers with water pumped from underground aquifers or diverted from streams.
“Sprinkler frost protection is very effective in many areas,” Battany said. “The concern we have in California is that water is becoming more limited. We don’t have the ability to easily import water from other areas to our coastal regions, and our local supplies are being stretched quite thin.”
Some farmers are considering wind machines, which mix warmer air high above the ground with air closer to the ground to raise the temperature. But wind machines are expensive, and the potential effectiveness depends on the strength of the temperature inversion. UC scientists are now gathering data to help inform farmers before making the costly investment.
Battany and his colleagues - Rhonda Smith, UCCE advisor in Sonoma County, Richard Snyder, UCCE specialist in the Department of Land, Air and Water Resources at UC Davis, and Gwen Tindula, UCCE staff research associate - are collecting temperature inversion data at different locations in 60 coastal vineyards throughout three counties to document inversions during frost events.
The scientists installed 35-foot-high meteorological towers with data loggers at the top and at the five-foot height to measure the difference in temperature. In the first year of the study, there were useful inversion conditions on nearly three-fourths of the nights when there was frost.
“That’s a fairly good success rate,” Battany said. “The wind machine will provide quite a bit of protection under those conditions.”
The study will continue this year and in 2014. Farmers who wish to install their own meteorological towers with data loggers can do so at a cost of about $250 each. Installation instructions and specifications are available on the UCCE website.
The UCCE research is funded with a grant from the American Vineyard Foundation and a CDFA Specialty Crops Block Grant.
For more details, see the video below:
- Author: Pat Bailey
The study also included researchers from Arcadia Biosciences and Acharya N.G. Ranga Agricultural University, India.
The finding is particularly important to the nearly $2 billion lettuce industries of California and Arizona, which together produce more than 90 percent of the nation's lettuce. The study results appear online in the journal The Plant Cell.
"Discovery of the genes will enable plant breeders to develop lettuce varieties that can better germinate and grow to maturity under high temperatures," said the study's lead author Kent Bradford, a professor of plant sciences and director of the UC Davis Seed Biotechnology Center.
"And because this mechanism that inhibits hot-weather germination in lettuce seeds appears to be quite common in many plant species, we suspect that other crops also could be modified to improve their germination," he said. "This could be increasingly important as global temperatures are predicted to rise."
Most lettuce varieties flower in spring or early summer and then drop their seeds -- a trait that is likely linked to their origin in the Mediterranean region, which, like California, characteristically has dry summers. Scientists have observed for years that a built-in dormancy mechanism seems to prevent lettuce seeds from germinating under conditions that would be too hot and dry to sustain growth.
While this naturally occurring inhibition works well in the wild, it is an obstacle to commercial lettuce production.
In the California and Arizona lettuce industries, lettuce seeds are planted somewhere every day of the year -- even in September in the Imperial Valley of California and near Yuma, Ariz., where fall temperatures frequently reach 110 degrees.
In order to jump-start seed germination for a winter crop in these hot climates, lettuce growers have turned to cooling the soil with sprinkler irrigation or priming the seeds to germinate by pre-soaking them at cool temperatures and re-drying them before planting -- methods that are expensive and not always successful.
In the new study, researchers turned to lettuce genetics to better understand the temperature-related mechanisms governing seed germination. They identified a region of chromosome six in a wild ancestor of commercial lettuce varieties that enables seeds to germinate in warm temperatures. When that chromosome region was crossed into cultivated lettuce varieties, those varieties gained the ability to germinate in warm temperatures.
Further genetic mapping studies zeroed in on a specific gene that governs production of a plant hormone called abscisic acid -- known to inhibit seed germination. The newly identified gene "turns on" in most lettuce seeds when the seed is exposed to moisture at warm temperatures, increasing production of abscisic acid. In the wild ancestor that the researchers were studying, however, this gene does not turn on at high temperatures. As a result, abscisic acid is not produced and the seeds can still germinate.
The researchers then demonstrated that they could either "silence" or mutate the germination-inhibiting gene in cultivated lettuce varieties, thus enabling those varieties to germinate and grow even in high temperatures.
Other researchers on the study were: Post-doctoral researcher Heqiang Huo and staff researcher Peetambar Dahal, both of the UC Davis Department of Plant Sciences; Keshavulu Kunusoth of Acharya N.G.
Ranga Agricultural University, India; and Claire McCallum of Arcadia Biosciences, which provided the lettuce lines with variants of the target gene to help confirm the study's findings.
Funding for the study was provided the U.S. Department of Agriculture National Institute of Food and Agriculture and the National Science Foundation.
- Author: Pamela Kan-Rice
The daylong forum, part of ANR’s Statewide Conference in Ontario, Calif., will feature two moderated panels and keynote addresses by Mary Robinson, former president of Ireland and president of the Mary Robinson Foundation – Climate Justice, and Wes Jackson, founder and president of The Land Institute.
Michael Specter, global issues writer for The New Yorker magazine, will moderate the first panel, which will focus on the geopolitical, ethical, economic, environmental and technical challenges facing food systems from a global perspective. Award-winning author and journalist Mark Arax will moderate the second panel, which will address the implications, responsibilities and innovative opportunities from a California perspective.
The panelists will include a mix of UC and non-UC experts and thought leaders. View a list of speakers at http://food2025.ucanr.edu/Speakers.
“As a public research university, we’re a recognized leader in tackling the world’s toughest challenges,” said Barbara Allen-Diaz, UC vice president for agriculture and natural resources. “Building on our expertise in agriculture and finding practical, science-based solutions, it falls to us to convene these sorts of conversations and look far beyond the borders of our campuses. Only through discussions of this nature will people find the common ground to move the world forward on what is a compelling, complex and crucial issue.”
The general public is encouraged to view the live webcast and join the conversation on Twitter by following (hashtag)Food2025. To learn more about the UC Global Food Systems Forum and to sign up to view the webcast, visit http://food2025.ucanr.edu.
Food forum at a glance
- WHAT: Live webcast of UC Global Food Systems Forum at http://food2025.ucanr.edu
- WHO: World-renowned leaders in food systems dialogue. See a list at http://food2025.ucanr.edu/Speakers
- WHEN: April 9, 2013 (9 a.m.-5 p.m. PDT)
- WHERE: Register for the webcast at http://food2025.ucanr.edu/Webinar
- Author: Diane Nelson
One notion — the so-called “fridge-test” theory — says you can determine the purity of your extra virgin olive oil (EVOO) by putting it in your refrigerator. If it solidifies, you can trust your EVOO is pure — or so the theory goes.
Is that scientifically accurate?
No, according to new research from the UC Davis Olive Center. Testing seven samples under cold conditions over eight days, researchers discovered the fridge test is unreliable in detecting either the purity or quality of olive oil.
“None of our samples showed any signs of congealing after 60 hours in a laboratory refrigerator set to 40.5 degrees Fahrenheit,” said Dan Flynn, executive director of the UC Davis Olive Center. “Even after 180 hours, the samples never fully solidified.”
“Wouldn’t it be nice to have such a simple test that could indicate an olive oil’s market grade, but it is much more complicated than that,” said Paul Vossen, UC Cooperative Extension advisor in Sonoma and Marin counties.
“All olive oils contain a small amount of saturated fatty acids that solidify at refrigerator temperatures,” said Vossen, an olive oil expert. “The amount of solidification is equal to the amount of saturated fatty acids in the oil, which depends mostly on the varieties of olives used to make the oil and to a lesser extent where the olives were grown. Solidification does not indicate freshness, purity, flavor, extra virgin grade, or any other quality parameter.”
The fridge-test theory surfaced on a recent episode of The Dr. Oz Show which aired Feb. 11, 2013, to more than 3 million viewers. While cautioning his method isn’t fool-proof, Dr. Oz. encouraged viewers to test the purity of EVOO by seeing if it solidifies in the fridge.
“After the show aired, we were swamped with calls from people who were concerned they were being ripped off,” Flynn said.
So the Olive Center conducted a study. They refrigerated seven samples, including two EVOOs, an olive oil, a canola oil, a safflower oil, and two blends. Some samples showed minor congealing at the bottom of the bottles, but none solidified completely.
“It’s true that waxes and long-chain fatty acids in extra virgin olive oil can lead to the oil solidifying in the cold, although relative amounts of these compounds vary from oil to oil,” the study said.
Olive oils are graded based on how the oil is extracted from olives and on chemical and sensory standards. True extra virgin olive oil is extracted from olives without heat or chemicals and must have no defective flavors such as rancidity. Extra virgin olive oil is more expensive than other oils and is therefore an attractive product for fraud.
Using sensory and chemistry testing, the UC Davis Olive Center is working on dependable methods for detecting when an extra virgin olive oil is fraudulently labeled. In the meantime, the center advises consumers to choose an oil within 15 months of the harvest day (not the best-before date), look for a certification seal indicating that the oil passed chemical and sensory tests, and seek (and store) oils protected from light.
- Author: Janet L. White
- Author: Aubrey White
As California legislators focus on nitrogen use in agriculture and its ability to contaminate groundwater, potential regulation on fertilizer use will require solid information on the amount of fertilizer used by California farmers, and the extent to which that usage contributes to environmental pollution. A new study published in California Agriculture evaluates trends in fertilizer use by California's major crops. It also shows that major deficiencies in data collection need to be addressed in order to develop effective policies regarding fertilizer use.
The publication is one of the first peer-reviewed articles to emanate from the California Nitrogen Assessment (an ongoing project at UC Davis). Assessment research documents that while there are many pathways through which nitrogen can enter the environment, inorganic fertilizer use is responsible for the largest fraction of new nitrogen introduced into California annually. Currently, over 600,000 tons of nitrogen fertilizer are sold in the state each year.
Information on fertilizer sales, however, is not an accurate indicator of fertilizer application, and authors found that fertilizer use data is not easy to come by — either because it is not tracked at relevant scales or because data sources are inconsistent.
"We found ourselves with very limited information to understand an issue with sweeping implications for California agriculture,” says Todd Rosenstock, the article's lead author. "We dug deep to create an accurate picture of fertilizer use in the state, but the remaining gaps will require attention.”
To estimate the amount of nitrogen applied to different crops around the state, authors aggregated data from different sources, including grower surveys and University of California studies, and show application rates for 33 of California's major crops.
While nitrogen fertilizer use on a crop-by-crop basis has risen over the last three decades, this increase has been more modest than fertilizer sales suggest. Between 1973 and 2005, fertilizer sales increased 31 percent, but nitrogen application rates increased on 25 percent across the 33 crops studied. Both data sets reflect increased nitrogen application and a shift to growing more nitrogen-intensive crops.
For many crops, nitrogen use increases have been accompanied by well-recorded yield increases — at rates that show nitrogen's benefit, and also suggest that farmers may be becoming more agronomically nitrogen-efficient, requiring less nitrogen per unit of production.
"In the absence of good information, we could do the wrong thing,” says Tom Tomich, co-author of the article and director of the Agricultural Sustainability Institute at UC Davis.
"Regulation without supporting data could fail to address the heart of the problem, or could damage agriculture,” says Tomich, who is also professor in the Department of Environmental Science and Policy at UC Davis, W.K. Kellogg Endowed Chair in Sustainable Food Systems and director of Sustainable Agriculture Research and Education Program. "Better information on nitrogen use is indispensable to collaborative development of effective solutions that can increase nitrogen use efficiency and save farmers money.”
The article makes recommendations on how data could be better compiled to improve our understanding of statewide trends in fertilizer use. To read the article, visit http://ucanr.edu/calagnassessment.
This article is part of an ongoing study, the California Nitrogen Assessment (CNA), a project of the Agricultural Sustainability Institute at UC Davis and UC Sustainable Agriculture Research and Education Program. The CNA reviews existing data on nitrogen to draw connections between nitrogen use, surplus, and established environmental and human health effects of excess nitrogen. The CNA is a stakeholder-driven assessment that seeks public input on its research and products. To learn more about the California Nitrogen Assessment, visit http://nitrogen.ucdavis.edu.
