Posts Tagged: walnuts
‘UC Wolfskill’ walnut will allow earlier harvest
UC Davis researchers have bred a new walnut variety designed to provide growers a way to harvest earlier and boost the harvest efficiency of California's $1.6 billion walnut industry.
The new “UC Wolfskill” walnut has yield, quality and light color similar to Chandler, which is a late-harvesting walnut and the state's leading variety. UC Wolfskill was bred in 2003 from a cross of Chandler with the Solano walnut. UC Wolfskill combines the color and shell traits of Chandler with the earlier harvest date and kernel fill of Solano.
“The release of UC Wolfskill means growers can spread out their harvest and still have a really high-quality nut that will fetch top-notch prices and provide similar yields,” said Pat J. Brown, breeder and professor with the UC Davis Department of Plant Sciences.
Over 99 percent of the nation's walnuts are grown in California. More than half of the state's bearing acres are the late-harvest Chandler walnuts.
“The California walnut industry needs earlier harvesting walnut varieties to provide efficient use of harvesting, drying and processing equipment,” said breeder Chuck Leslie, with the UC Davis Walnut Improvement Program. “UC Wolfskill can be harvested 12 to 14 days earlier than Chandler and provides consistently light to extra light color.”
Handlers judge the value of a walnut based on its color and how well it halves while processing. In blind quality evaluations by commercial graders, the UC Wolfskill was often not distinguished from Chandler.
UC Wolfskill was originally planted and evaluated at UC Davis, and field trials with growers began in 2011.
“The commitment of our walnut growers, as collaborators, is the foundation that makes this release possible. The Board is extremely grateful for the long-term partnership of our growers and the UC, in finding innovative solutions that help us solve for critical needs,” said Michelle Connelly, executive director of the California Walnut Board.
The California Walnut Board funded the research. UC Wolfskill is currently available to California nurseries for propagation in California and sales to growers throughout the United States. Nurseries interested in propagating and selling this cultivar may obtain a license from UC Davis InnovationAccess.
Una idea loca: un poco de estrés podría ser bueno para los nogales
Cuando se trata de irrigar los nogales, la mayoría de los cultivadores de California creen que se necesita empezar temprano para mantener los árboles saludables y productivos durante todo el largo y caluroso verano. Pero de acuerdo con los resultados sorprendentes de un experimento a largo plazo realizado en una plantación nogalera de Red Bluff, los cultivadores pueden mejorar la producción si se abstienen de regar hasta más adelante en la temporada y miden directamente las necesidades de riego de los árboles.
Los resultados obtenidos por los investigadores de la Universidad de California podrían ayudar a los granjeros a optimizar el uso de agua.
“Es algo revolucionario”, señaló el productor de nogales Hal Crain, quien abrió las puertas de su huerto a los investigadores para hacer las pruebas de optimización de riego. “Tengo claro que se puede mejorar la calidad y producción de la nuez aplicando agua en base a lo que el árbol quiere y necesita, en lugar de regar cuando está caliente en el exterior y la tierra está seca. Eso es importante para los cultivadores de nogales y para toda la industria agrícola”.
Cambiando el paradigma
Crain es la segunda generación de granjeros cuya familia ha cultivado nogales durante 55 años en los condados de Butte y Tehama. Al igual que la mayoría de los productores de nogales, Crain siempre ha iniciado el riego a principios o mediados de mayo cuando los días empiezan a calentarse y los árboles a echan las hojas.
“Esa es una práctica normal para probablemente el 90 por ciento de los productores de nueces de California”, mencionó Crain, mientras caminaba entre los árboles en una soleada tarde. “La teoría es que cuando se riega temprano, se preserva la humedad profunda en el suelo, la cual los árboles necesitan para sobrevivir el calor del verano”.
Pero no es así como funciona, según muestra la investigación. En cambio, los árboles que crecen en suelos saturados a principios de la temporada no desarrollan las raíces profundas que necesitan para prosperar.
“Con toda el agua allí en la superficie, las raíces más bajas sufren”, explicó Bruce Lampinen, especialista en el manejo de huertos de Extensión Cooperativa de UC del Departamento de Ciencias Botánicas de UC Davis de. “Los árboles terminan con un sistema de raíces muy superficiales, el cual no les sirve cuando tratan de extraer humedad del suelo más adelante”.
Lampinen había sospechado que los nogales estaban obteniendo mucha agua en la primavera.
“Mucho de los síntomas que vemos, como la hojas amarillas y varias enfermedades pueden ser explicadas por el exceso de riego”, dijo Lampinen.
Así que Lampinen hizo lo que los científicos hacen: preparó un experimento. Hace cinco años, con fondos de la Junta de Nogaleros de California y del Departamento de Agricultura de EUA, unió esfuerzos con Ken Shackel, profesor de ciencias botánicas de UC Davis y Allan Fulton, asesor de riego de Extensión Cooperativa de UC. Juntos, encabezaron a un equipo de científicos que realizaron pruebas de riego en el rancho de Crain.
“Hal es un socio excepcional”, manifestó Fulton. “Los granjeros deben hacer muchos ajustes durante un experimento como este, con investigadores entrando y saliendo del huerto a todas horas. Él tuvo que trabajar en torno a nuestra gente y horario de nuestros tratamientos de agua. Siempre está dispuesto a experimentar con tecnología y a aprender nuevas cosas y compartir lo que aprende con otros cultivadores. Hal completa el círculo”.
Una nuez dura de cascar
¿Cuándo es el mejor tiempo para regar? Los investigadores dicen que la respuesta la tienen los árboles. Los científicos usan cámaras de presión, las cuales son aparatos de aire a presión que miden una hoja o un brote pequeño para saber cuán duro está trabajando una planta para extraer humedad del suelo.
“No porque el suelo luzca seco significa que la planta está sufriendo”, indicó Shackel, quien se especializa en fisiología de las plantas. “Las cámaras de presión te permiten preguntar al árbol cómo se siente — es algo así como tomar la presión arterial de una persona — lo cual es una forma más exacta de medir las necesidades de riego de una planta”.
Durante los últimos cinco años, el equipo ha aplicado diferentes tratamientos de riego a cinco blocks de árboles. Un block obtiene un riego normal y temprano. Los administradores del huerto de Crain empiezan a regar los otros blocks cuando los árboles alcanzan diferentes niveles de estrés por falta de agua de acuerdo con las lecturas de la cámara de presión.
Los árboles que experimentan un estrés moderado son los que mejor se desempeñan. El riego usualmente inicia a mediados o finales de junio, varias semanas después de que empieza el riego normal.
“Te puedes dar cuenta solo con mirar ese block que los árboles están más sanos”, manifestó Crain, parado debajo de un dosel de árboles frondosos y verdes. “Y, estamos empezando a ver una mayor producción y calidad de nueces”.
La interpretación del estudio
La investigación está ayudando a los científicos a asesorar a los granjeros sobre el riego.
“Mi mayor aprendizaje en saber cuándo empezar a regar es un factor muy importante para la salud de tus árboles”, apuntó Lampinen.
Las cámaras de presión — algunas veces llamadas bombas a presión — pueden costar más de tres mil dólares y ya están desarrollo versiones de alta tecnología.
“Yo les digo a los granjeros que una bomba a presión se paga sola aun si solo la usan una vez al año para determinar cuándo deben empezar a regar”, añadió Lampinen.
Crain está ciertamente convencido.
“Cuando riegas basado en las necesidades de tus árboles, optimizan el agua”, dijo Crain. “En general no estoy usando menos agua, pero el agua que uso está produciendo más alimentos. Esas son buenas nuevas para cualquiera”.
Esta historia fue publicada originalmente en la edición de otoño del 2018 de la revista Outlook, la revista de los exalumnos de la Facultad de Agricultura y Ciencias Medioambientales de UC Davis.
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.”
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.”
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.
Genetic engineering for roots — not fruits
Even though U.S. consumers routinely buy and eat genetically engineered corn and soy in processed foods — most are unaware of the fact because the GE ingredients are not labeled.
When consumers are asked in surveys whether they would buy genetically engineered (GE) produce such as fruit, most say they would not buy GE produce unless there were a direct benefit to them, such as greater nutritional value.
Yet with continuing invasions and spread of exotic insects and diseases for which there is no known control, the potential importance of trees or vines with some form of genetically engineered resistance is on the rise. In California, such diseases include Pierce's disease in grapes, crown gall disease in walnuts, and the invasive citrus greening (huanglongbing or HLB) in citrus.
"These are potentially devastating diseases to California growers, who produce 70 percent of the fresh fruit and nuts for the entire United States," notes Victor Haroldsen, scientific analyst at Morrison and Foerster, in the current California Agriculture. "They are also a mainstay of the California economy. Fruit and nut tree crops accounted for one-third of the state's total cash farm receipts, or $13.2 billion in 2010."
Now, however, Haroldsen reports that there may be a way to satisfy both consumers and growers — called "transgrafting."
"In transgrafting the genetically engineered rootstock can potentially confer the whole plant with resistance to disease. Yet the rootstock does not transfer the modified genes to the fruits or nuts produced," said Haroldsen.
Although over 10 years old, transgrafting technology is just now nearing commercialization, partly due to the long generation times of most trees and vines. Two such transgrafting applications are: a crown gall-resistant walnut rootstock, and a grape rootstock that confers moderate resistance to Pierce's disease.
"The key advantage of transgrafting is that the plant's vascular system can selectively transport across graft junctions the proteins, hormones, metabolites and vitamins from the roots without changing the heritable genes or DNA sequence in the fruit or nut." says Haroldsen.
In recent research at UC Davis, Haroldsen (a former graduate student) and his colleagues confirmed that modified DNA and full-length RNA from the rootstock does not cross the "graft union" into the scion, in the walnut and grape applications, or in a tomato model of these two systems.
"These current GE applications address root or xylem pests and diseases, but future applications will likely target traits aimed at consumer needs such as increased nutritional value or improved flavor," said Haroldsen. "If perceived risks to personal health and the environment could be reduced, genetic engineering could benefit not only growers but Californians around the state," he adds.
New findings on benefits of “biofactors” in food
Can what we eat help fix what ails us? Research increasingly suggests the answer is “yes.” Many foods contain biofactors — biologically active compounds — that may prevent and treat illnesses including asthma, diabetes and heart disease, according to new studies from the UC Davis Center for Health and Nutrition Research (CHNR).
The upcoming July-September California Agriculture journal (to be posted by July 11) reports UC research into plant compounds (phytochemicals) that can help prevent or treat disease. The findings stem from pilot projects at the center, as well as other UC research. Articles focus on how micronutrients, biofactors and phytochemicals (plant compounds) can help reduce the risk of chronic diseases.
Phytochemicals and health. Epidemiological studies link particular diets to less risk of chronic diseases. Notably, the traditional Mediterranean diet — mostly vegetables, fruits and whole grains, with moderate amounts of nuts, olive oil and red wine — is associated with lower rates of heart disease, cancer, and Parkinson's and Alzheimer's diseases. However, it has yet to be firmly established that specific phytochemicals in our diets can protect against diseases. Nutritionists therefore advise eating a wide variety of plant-based foods rather than taking supplements.
Mitochondrial nutrients and aging. The Mediterranean diet is rich in plant compounds that boost mitochondria (organelles in our cells that convert glucose and other nutrients into energy) and so are known as mitochondrial nutrients. When mitochondria are scarce or have genetic defects that keep them from working properly, this can generate toxic metabolites and damaging free radicals.
“Mitochondria are central to aging,” says UC Irvine aging expert Edward Sharman. “Improving their function may modulate or delay the onset of diseases related to aging, such as type 2 diabetes and age-related macular degeneration.” Mitochondrial dysfunction also plays a key role in chronic illnesses such as heart disease, type 2 diabetes and inflammatory diseases such as arthritis.
A new essential nutrient? Another promising mitochondrial nutrient is pyrroloquinoline quinone (PQQ), which was first found in nitrogen-fixing soil bacteria and is now known to be ubiquitous.
“We’re exposed to PQQ all the time at low levels,” says CHNR co-director Robert Rucker, a UC Davis nutrition professor. “It can be derived from amino acids found in stellar dust, and stellar dust is what the earth is made of.”
While Escherichia coli and other common gut bacteria do not make PQQ, the soil bacteria provide it to the plants in our diet. Good sources include fermented soybeans, wine, tea and cocoa.
Animal studies show that PQQ affects health markedly. Rucker and his colleagues found that depriving rats of PQQ compromised their immune systems, and retarded their growth and reproductive rates. In contrast, restoring PQQ to their diets reversed these effects and returned them to good health. Moreover, PQQ stimulated nerve growth and counteracted aging in cultured cells.
Rucker and his colleagues found that, like hydroxytyrosol, PQQ increases the number of mitochondria in cells. “It’s also an extremely good antioxidant and anti-inflammatory agent,” he says.
Personalized medicine. Understanding what biofactors do in our bodies could ultimately lead to personalized medicine, where nutrition-based treatments are tailored to the particulars of each person’s biochemistry. This individual variation at the biochemical level may help explain the inconsistent outcomes of research on omega-3 fatty acids and inflammation.
“The studies are mixed,” says UC Davis pulmonologist Nicolas Kenyon. “Some have shown little effect and others have shown that omega-3 fatty acids can reduce arthritis and inflammation in blood vessels.”
This genotyping is targeted to DNA sequences associated with asthma and so is not comprehensive.
“Some people are nervous about genome-wide analysis, which is scary because none of us is perfect,” Kenyon says. “But people are more interested when the focus is specific screening that could increase their chances of treatment.”