Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
University of California
Division of Agriculture and Natural Resources

Posts Tagged: UC Davis

Trying leafy greens from a sweet potato plant

This time of year, it can be hard to resist the pull of sweet potatoes — roasted, mashed with butter, and topped with a combination of delectable treats from maple syrup to pecans to marshmallows. But did you know that the green leaves of the sweet potato plant also have the potential to be a tasty, nutritious food?

In Ethiopia, where sweet potatoes can be a staple crop, UC Davis graduate student Lauren Howe recently helped farmers taste test the leaves and consider this familiar crop in a new culinary light.

Watch a video to learn how to prepare sweet potato leaves:

The leaves of this drought-tolerant plant offer farming households there an alternative — and nutritious — food in the lean season, while they are waiting for its starchy, tuberous roots to be ready to eat. Introducing sweet potato leaves as a food option is intended to help farmers better diversify their families' diets, to include a wider variety of vegetables in addition to staple foods, especially during the dry season.

Lauren shared her experiences in Ethiopia on the Agrilinks website, where she recently won the Agrilinks Young Scholars blog contest with her writing and a short video from the field.

From right, Lauren Howe of UC Davis and Tesfaye Kassa of SACE interview farmers about how they currently manage sweet potato crops on their farms.

Boots on the ground with sweet potato farmers in Ethiopia

Lauren traveled to Ethiopia this summer to work with an organization called Send A Cow Ethiopia (SACE), on a Trellis Fund project. As part of the Horticulture Innovation Lab, each Trellis Fund project connects an organization in a developing country with a grad student from a U.S. university, to work together to benefit local farmers, while building the capacity of both the local organization and the student.

In Ethiopia, SACE helped Lauren better understand local contexts by connecting her with farming households to interview about their current farming practices and the role of sweet potatoes in their diets.

Later they traveled to meet with a group of about 25 farmers in the Ukara community to harvest leaves, cook together and discuss their perceptions of the leaves as a vegetable option.

“We are producing a huge amount of sweet potato per year," explained Feleke Lera, a son of farmers in Ukara. "But before, we had no knowledge about the leaves.”
 
Lauren harvests sweet potato leaves with farmers in Ukara.
 
In Ukara, the group prepared the sweet potato leaves three different ways – sauteed, cooked with corn or maize flour in a dish called fosese, and in a salad.
 

Reflecting on taste tests, new foods, and rural communities

After preparing and tasting the sweet potato leaves, the group in Ukara discussed which dish they preferred, whether they would adopt this new practice of eating sweet potato leaves, how this practice might affect their forage supply to feed their livestock, and what their friends and family members might think of this new food. 
 
"I deeply appreciated how food is truly a universal language and the preparation, cooking and act of eating itself are relatable across cultures," Lauren wrote in her blog post.
 

Lauren's own passion for food and witnessing how food can help build community is an important part of her reflection on this experience:

"This project is about creating tasty dishes to persuade people about the nutritional benefits of a new ingredient. It is gathering families, friends and neighbors to sit down to a communal meal (already a strong Ethiopian practice), breaking bread together, sharing stories, experiences and hopes for the future."

For more, go read the rest of Lauren's blog post and check out her short video too.

Lauren at a taste test in another community called Gurumo Koysha, where farmers overwhelmingly preferred the sautéed sweet potato leaves to the sautéed kale. The activity was intended to be a blind taste test, but Lauren reported that keeping the dishes secret was more difficult to do than originally planned.

Background and related international agricultural research

Lauren's experience with a Trellis Fund project in Ethiopia was supported by the Horticulture Innovation Lab, a research program led by Elizabeth Mitcham of the UC Davis Department of Plant Sciences, with funding from the U.S. Agency for International Development. With a focus on fruit and vegetable innovation, the Horticulture Innovation Lab seeks to empower smallholder farmers in developing countries to earn more income and better nourish their communities — as part of the U.S. government's global Feed the Future initiative.

Past research from the Horticulture Innovation Lab has focused on other leafy greens, specifically African indigenous vegetables, and also on sweet potatoes themselves (orange-fleshed sweet potatoes, that is). Though the program has not done in-depth research on sweet potato leaves for human consumption beyond this small Trellis Fund project, you can find more information about eating sweet potato leaves and tips in this bulletin from the University of Arkansas Cooperative Extension, and a wealth of information about sweet potato farming and gardening from the University of California Vegetable Research and Information Center. 

Related Food Blog posts:

 

Sweet potato leaves in Ethiopia - Horticulture Innovation Lab photo by Lauren Howe/UC Davis
Sweet potato leaves in Ethiopia - Horticulture Innovation Lab photo by Lauren Howe/UC Davis

close-up on sweetpotato leaves, stems and plant

Posted on Monday, November 19, 2018 at 9:02 AM
Focus Area Tags: Agriculture Health Innovation

A nutty idea: A little stress could be good for walnuts

When it comes to watering walnuts, most California growers believe you need to start early to keep trees healthy and productive throughout the long, hot summer. But according to striking results from a long-term experiment in a walnut orchard in Red Bluff, growers can improve crop production if they hold off irrigation until later in the season and directly measure their trees' water needs.

The findings from researchers at the University of California may help farmers optimize water use.

“It's a game-changer,” said walnut grower Hal Crain, who welcomed researchers on to his orchard to test irrigation optimization. “It's clear to me you can improve nut quality and yield by applying water based on what the tree wants and needs, rather than just watering when it's hot outside and the soil is dry. That's a big deal for walnut growers and for the entire agricultural industry.”

Hal Crain's family has been growing walnuts for 55 years.

 Changing the paradigm

Crain is a second-generation farmer whose family has been growing walnuts in Butte and Tehama counties for 55 years. Like most walnut farmers, Crain had always started irrigating in early to mid-May when the days grew warmer and the trees sprouted leaves.

“That's standard practice for probably 90 percent of California's walnut growers,” said Crain, walking amid his trees on a sunny afternoon. “The theory is that when you irrigate early, you preserve the deep moisture in the soil that trees need to survive the heat of summer.”

But that's not how it works, the research shows. Instead, trees that grow in saturated soil early in the season don't develop the deep roots they need to thrive.

“With all the water right there at the surface, the lower roots suffer,” explained Bruce Lampinen, UC Cooperative Extension orchard management specialist with the UC Davis Department of Plant Sciences. “Trees end up with a very shallow root system, which doesn't serve them well as they try to extract moisture from the soil later on.”

Lampinen has long suspected that walnuts were getting too much water in the spring.

“A lot of the symptoms we see like yellowing leaves and various diseases can all be explained by overwatering,” said Lampinen.

So Lampinen did what scientists do: He set up an experiment. Five years ago, with funding from the California Walnut Board and the U.S. Department of Agriculture, he joined forces with Ken Shackel, a plant sciences professor with UC Davis, and Allan Fulton, an irrigation adviser with UC Cooperative Extension. Together, they led a team of scientists testing irrigation on Crain's ranch. 

“Hal is an exceptional partner,” Fulton said. “Farmers have a lot to accommodate when they host an experiment like this, with researchers going in and out of the orchard at all hours. He had to work around our people and the timing of our water treatments. He's always eager to experiment with technology and learn new things, and he shares what he learns with other growers. Hal completes the circle.”

Tough nut to crack

When is the best time to irrigate? Researchers say the trees hold the answer. Scientists use pressure chambers, which are air-pressure devices that measure a leaf or small shoot to gauge how hard the plant is working to pull moisture from the soil.

“Just because the soil looks dry doesn't mean the plant is suffering,” said Shackel, who specializes in plant physiology. “Pressure chambers let you ask the tree how it's feeling — sort of like taking a human's blood pressure — which is a much more accurate way to measure a plant's water needs.”

Professor Ken Shackel and Cooperative Extension Specialist Bruce Lampinen test pressure chamber in UC Davis walnut grove.

For the last five years, the team has been applying different water treatments to five blocks of trees. One block is getting standard, early irrigation. Crain's orchard managers begin irrigating the other blocks when the trees reach different levels of water stress based on pressure-chamber readings.

The trees that experience moderate stress are doing the best. Their irrigation usually starts in mid-to-late June, several weeks later than when standard watering begins.

“You can tell just by looking at that block that the trees are healthier,” said Crain, standing beneath a canopy of lush, green trees. “And, we're starting to see greater yields and better nut quality.”

Translating the research

The research is helping scientists advise farmers on irrigation.

“My biggest take-away is knowing when to start watering is a really important factor to the health of your trees,” Lampinen says.

Pressure chambers — sometimes called pressure bombs — can cost more than $3,000, and high-tech versions are under development.  

“I tell growers a pressure bomb would pay for itself even if you just used it once a year to determine when to start watering,” Lampinen said.

Crain is certainly convinced.

“When you irrigate based on your trees' needs, you optimize water,” Crain says. “I'm not using less water overall, but the water I do use is producing more food. That's good news for everyone.”

This story was originally published in the Fall 2018 issue of Outlook Magazine, the alumni magazine for the UC Davis College of Agricultural and Environmental Sciences. 

Posted on Tuesday, November 6, 2018 at 9:20 AM
Focus Area Tags: Agriculture

Change on the range

A new breed of ranchers is bringing diverse demographics and unique needs to rangeland management in California. These first-generation ranchers are often young, female and less likely to, in fact, own a ranch. But like more traditional rangeland managers, this new generation holds a deep love for the lifestyle and landscapes that provide a wealth of public benefit to California and the world.
 
California rancher Ariel Greenwood. (Brittany App/Brittany App Photography)

“When first-generation ranchers succeed, we all succeed,” says Kate Munden-Dixon, a Ph.D. student working with Leslie Roche, Cooperative Extension rangeland specialist with the UC Division of Agriculture and Natural Resources and the UC Davis Department of Plant Sciences.

Munden-Dixon and Roche recently discovered that many new livestock managers aren't plugged into information networks such as UC Cooperative Extension and rancher coalitions that provide science and strategies for making sustainable rangeland management decisions. This lack of connection can make first-generation ranchers more vulnerable when dealing with challenges like drought and climate variability, according to their study, which was recently published in Rangeland Journal.

To help bridge the gap, Munden-Dixon landed a $25,000 Graduate Student Grant from Western Sustainable Agriculture Research and Education, a USDA program, to reach out to new ranchers and rangeland managers. 

Why rangelands matter

More than one half of California — 38 million acres — is rangeland that provides open space, healthy watersheds, carbon storage, food, fiber and habitat for diverse plants and wildlife. UC Davis research indicates grasslands and rangeland have become more resilient at sequestering or consuming carbon dioxide pollution than forests in California, making them especially important in a warming world.

But rangeland and livestock production are at risk because more rangeland is being converted to housing and crop production. The average age of ranchers in California is 62, and fewer children are taking over the family ranch.   

Enter a new wave of rangeland managers. Many of these young ranchers don't yet have access to the capital required to purchase land and large head of cattle and other livestock. Instead, they often contract with public and private landowners to graze goats, sheep and cattle to restore landscapes and reduce fire vegetation.

“What we really need is support in connecting land and contract opportunities,” says Brittany Cole Bush, an “urban shepherdess” and former contract sheep and goat grazer. She now consults with land owners and public agencies from her home base in Southern California. “We need market research that shows the value that grazing brings to fire abatement, soil conservation and so much more. Market research would increase our value and help us become viable players.”

Kate Munden-Dixon
Expanding Extension

Munden-Dixon is interviewing 40 new rangeland managers from across California to explore how decision-making by different demographics influences adaptation to climate change and quality of life. Munden-Dixon and her team are also hosting workshops to make sure Cooperative Extension specialists understand and can respond to all ranchers' needs.

“There is both a need and opportunity for a new generation of livestock managers that is able to adapt to California's changing climate,” Munden-Dixon says. “This next generation may not look like your typical rancher, so we want to ensure organizations are helping all ranchers succeed, regardless of their demographics or land tenure.”

The power of connection

Munden-Dixon would like to become a Cooperative Extension specialist herself one day. Working with first-generation ranchers reminds her that collaboration and public engagement are critical to addressing issues in sustainable agriculture.

“There is no one answer or single expert when it comes to building healthy food systems,” Munden-Dixon says. “We find solutions when we work together.”

See this story in the Fall/Winter 2018 issue of Outlook, a magazine from the UC Davis College of Agricultural and Environmental Sciences, and at the UC Davis Science & Climate website.

 
Posted on Tuesday, October 30, 2018 at 4:58 PM
Focus Area Tags: Environment

Connecting with farmers over pineapple postharvest practices

At the end of a long year, sometimes it helps to reconnect with what motivates your work.

For Karin Albornoz — a Ph.D. student who works in the Diane Beckles Lab at UC Davis on molecular biology related to tomato postharvest chilling injury — that means getting out into the world to work directly with small-scale farmers.

"I spend so much time in the lab," she said. "Sometimes I spend a whole day in the lab extracting RNA or writing a paper. This reminds me why I am doing this work: to make a real-world impact."

Just over a week ago, she returned from a trip to Uganda where she did exactly that. In partnership with a local organization called Ndibwami Integrated Rescue Project (NIRP), Albornoz shared her expertise with farmers through several hands-on workshops about improving harvest practices and postharvest handling of pineapple, passion fruit and tomatoes. Her work was supported by the Horticulture Innovation Lab, an international agricultural research program led by UC Davis with funding from the U.S. Agency for International Development as part of Feed the Future, the U.S. government's global hunger and food security initiative.

Though Albornoz has worked with rural farmers before, this was her first time working in Africa. 

"Everywhere I looked, things were growing. There were people working in the field, women cooking, and everyone was working with food," she said. "I know there's a lot of stigma – when you talk about Africa, you see people's faces change and they're thinking about things like drought and famine and starving children. But what I saw doesn't fit that stereotype. The challenges they are facing seem to be about not having access to opportunities."

The workshops she led are part of the NIRP organization's efforts to connect farmers with more lucrative markets that pay higher prices for quality produce.


In this 2-minute video, Karin Albornoz visits a pineapple farm, leads a pineapple training and discusses next steps for this project led by NIRP in Uganda. The video clips and photos were taken by Karin while she was working and edited by Hallie Casey for the Horticulture Innovation Lab.


For months, Albornoz has been in contact with NIRP and making plans for the farmer workshops. She prepared postharvest handling manuals for each crop — pineapple, passion fruit and tomato — and asked questions to better understand local resources and the farmers' existing knowledge.

During her 2 weeks in Uganda, she visited farmers' fields and led three full-day workshops. The first workshop for about 50 farmers focused on pineapple — starting with understanding local quality parameters for this fruit, then best practices for harvesting, sanitation, storage and transportation. The second workshop was focused on tomato, with a similar structure, and the third workshop on passion fruit.

During the pineapple workshop, farmers had a chance to measure the fruit's total soluble solids through a refractometer.

Her favorite moment? The farmers' first chance to use a refractometer, to measure soluble solids and learn about sugar levels in the fruit. The refractometers were part of a small toolkit the organization will continue to use.

"They were excited to handle this device and see, in numbers, how the sugar levels of the fruit changed depending on the stage of maturity," she said. "Everyone in the room had a chance to try it."

Karin Albornoz leads a workshop in postharvest handling of pineapple in Uganda.

The experience reinforced her commitment to working with farmers and solving agricultural problems.

"A major mistake is to think that you are going just to train or teach other people because those people are always going to end up teaching you too," Albornoz said. "I made a promise to myself years ago, a personal commitment to working with people in vulnerable situations. I have to do this. Working in agriculture can be a very powerful tool to have an impact in the world."

As Karin's mentor and an Associate Professor in the UC Davis Department of Plant Sciences and Agricultural Experiment Station, Diane Beckles supported Karin's work outside of the lab and views such an experience as important to scholarly development.

"Something magical happens when we teach and engage in outreach," Beckles said. "We often deepen our understanding of what we are teaching, and interacting and engaging with others changes us in that process. It alters how we view and think about science in a way that is positive and rewarding, even though it is not easily quantified."

 More information:

thumbnail: Karin Albornoz leads a workshop in postharvest handling of pineapple in Uganda.
thumbnail: Karin Albornoz leads a workshop in postharvest handling of pineapple in Uganda.

Woman teaching class on pineapple

Posted on Wednesday, December 20, 2017 at 8:47 AM

'Know beans' about a delicious Thanksgiving

Navy beans, soaked overnight and ready to cook. The name is derived from the fact that they were a staple food of the U.S. Navy in the early 20th century, according to the California Dry Bean Council. (Photo: Kathy Keatley Garvey)
If you say "I don't know beans" about beans, you ought to.

Beans are one of civilization's earliest cultivated crops, dating back to the early seventh millennium BCE. Today there are more than 40,000 varieties of beans worldwide.

Beans can also have a place on the Thanksgiving table. The Maple Spice blog for vegans shares a meat-free substitute for turkey that combines mashed white canelli beans, nutritional yeast, vital wheat gluten and spices to create a loaf that slices like turkey breast. UC CalFresh, one of the UC Agriculture and Natural Resources' nutrition education programs, developed a recipe for black bean and mango salad that makes a healthful and colorful accompaniment to a traditional Thanksgiving meal. (The recipe is below.)

"Not only are beans a healthy food choice, but they are also a healthy choice for our world," said UC Cooperative Extension advisor and dry bean expert Rachael Freeman Long. "Beans fix most of their own nitrogen so require fewer inputs for production compared to other sources of protein and they're cheap! Plus some, like garbanzos, are grown during the wintertime, so they're less dependent on irrigation."

The different varieties of beans include garbanzos (chickpeas) as well as black eyes, limas, and common beans like pintos and kidneys.

You probably won't find a bigger fan of beans than Rachael Long. "I eat them at least once a week or more," she said. "I love going on our Cal Beans website and getting new recipes. Summer time, I love beans on my salad, especially garbanzos. At this time of year, I love soups with beans. My favorite is the kale white bean sausage soup. If I want to go vegetarian, I'll leave out the sausage or sometimes fry up some tofu sausage for flavor. And, it just so happens that this is the soup in the current bean blog. I got the original recipe from one of our nutrition staff at our office."

Yolo County Farm advisor Rachael Long in a dry bean research field at the University of California, Davis. (Photo: Kathy Keatley Garvey)

Long says that Cal Beans is an important site for bean growers and industry folks, too. "It's supported by the California Dry Bean Advisory Board, an important funding source for my work. Right now, I have a grant to look at seed moisture and quality at harvest (possibly drying down seed too much at harvest results in internal injury to planting beans (seed stock)."

What do you know about beans? Do you know that California grows the canning quality beans?

"We have the perfect weather conditions for those large, creamy beige-colored beans," Long said. "Other states like Washington grow about 100,000 acres of garbanzos for humus (but a lower quality bean and we can't compete with their free water via rainfall."

California farmers supply virtually all of our country's dry lima beans, Long notes.  In 2012, California farmers grew about 23,000 acres of baby and large limas, valued at $30 million that year, according to the National Agricultural Statistics Service.

California farmers supply virtually all of our country's dry lima beans, says Yolo County farm advisor Rachael Long. This photo was taken in 2013 at a research site during the UC Davis Dry Bean Field Day. (Photo: Kathy Keatley Garvey)

Long has authored two UC ANR manuals about beans (Lima Bean Production in California and Common Dry Bean Production Manual) and is just finishing the garbanzo production manual (it's in peer review).

"Lima beans are a major dry bean crop for California, representing a significant portion of the total dry bean acreage in 2013," she wrote in the Lima Bean Production in California. "Lima beans are primarily grown for the dried edible white bean in California, although a limited but stable acreage is also for seed production. As with all dry beans, limas are a nutritional and healthy food choice, being an excellent source of protein, fiber, vitamins, and minerals. Lima beans are also an important rotation crop for farmers because the plants fix nitrogen, add biomass to the soil, and require relatively few pesticides."

Lima beans belong to the species Phaseolus lunatus, distinct from the common bean, P. vulgaris.

"Common dry beans include the market classes kidney, cranberry, pink, black, white, yellow, pinto, and red, all of which are different types of a single species (Phaseolus vulgaris) that was originally domesticated several thousand years ago in the areas that are now Mexico and South America," Long wrote in the Common Dry Bean Production Manual. "Natural selection and breeding programs lead eventually to the current market classes, which are mainly distinguished by seed size, color, and shape, and plant growth habit. Currently, there are no commercially available genetically modified varieties of P. vulgaris."

"Dry beans," Long points out, "are grown in California mainly for human consumption, though a limited but stable acreage is dedicated to seed production. Dry beans are nutritious: they are high in starch, protein, and dietary fiber, they have no cholesterol, and they are an excellent source of iron, potassium, selenium, molybdenum, thiamine, vitamin B6, and folic acid. The U.S. Department of Agriculture considers dry beans to be both a vegetable and a protein source."

Beans are delicious, nutritious and brilliant. This is a cranberry bean in the UC Davis research field. (Photo: Kathy Keatley Garvey)

Rosane Oliveira, director of the UC Davis Integrative Medicine Program and an adjunct assistant professor in the UC Davis School of Medicine's Department of Health Sciences, recently praised beans as one of the "Fab 4" plant foods in her "21-Day Food Challenge" blog.

Beans are brilliant, Oliveira says, because they:

  • Are an excellent source of fiber, protein, iron, and magnesium
  • May add up to 3-4 years to your life if you eat one cup a day
  • Keep your blood sugar level stable for up to six hours
  • Improve cardiovascular health
  • Decrease the risk of type 2 diabetes

Indeed, there's even a National Bean Day, observed annually on Jan. 6. Want to know more about beans? You'll find a wealth of information about dry beans from the U.S. Dry Bean Council.

Bottom line: Beans should be an important part of your diet. You can call them "nutritious," you can call them "delicious," or you can call them "brilliant." They're all three.

UC CalFresh mango and black bean salad
UC CalFresh mango and black bean salad

Ingredients:

  • 1 15-ounce can black beans, rinsed and drained
  • 2 cups peeled, pitted and diced fresh mango (about 2 small mangos)
  • 1/4 cup sliced green onions
  • 1/4 cup chopped bell pepper
  • 2 tablespoons lime juice
  • 2 tablespoons 100% orange juice
  • 1 tablespoon chopped fresh cilantro
  • 1/2 teaspoon chili powder
  • 1/4 teaspoon ground cumin

Mix together all ingredients in a large bowl. Salad may be served right away, but is best if covered and chilled for a least 1 hour for flavors to blend.

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