USDA

Using Fire to Keep Rangelands Viable for Grazing

USDA Agricultural Research Service - Thu, 04/24/2014 - 07:43
Using Fire to Keep Rangelands Viable for Grazing / April 24, 2014 / News from the USDA Agricultural Research Service
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  A research plot made up of about 75 percent purple threeawn plants. Link to photo information
ARS scientists have found "prescribed fire" used in the summer was much more effective, particularly after a wet spring, at controlling the invasive weed purple threeawn and giving perennial, sod-forming grasses a chance to regrown on rangeland. Click the image for more information about it.


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Using Fire to Keep Rangelands Viable for Grazing

By Dennis O'Brien
April 24, 2014

U.S. Department of Agriculture (USDA) researchers are looking for ways to use "prescribed fire" to control a weed that is colonizing disturbed soils and overtaking western grazing land. When fully grown, the weed, called purple threeawn, has sharp prongs that make it undesirable to cattle. When cattle have no other choices and are forced to eat purple threeawn as a staple of their diet, they fail to thrive.

Range ecologist Lance Vermeire and range technician Dustin Strong, with the USDA's Agricultural Research Service (ARS) in Miles City, Montana, wanted to determine whether fire could reduce the abundance of purple threeawn and create more balanced ecosystems. ARS is USDA's principal intramural scientific research agency, and this research supports the USDA priority of promoting international food security.

Carefully staged "prescribed fire" can reset a rangeland's biological clock, breathe new life into an ecosystem, and give perennial, sod-forming grasses that are good sources of forage a better chance to take hold.

A key question is when to use fire. Most prescribed fires are set in rangelands during spring or fall, but a plant's response to fire varies with its stage of development and activity level. Most native grasses in Montana are cool-season plants that have adapted to the natural cycle of frequent summer wildfires. They go dormant in the summer, making them less susceptible to summer fires. Purple threeawn, however, is a warm-season species that grows during the summer, which should make it more susceptible to summer fires.

In a study at two Montana sites, plots were either burned during the summer or fall or were not burned at all, and each of those treatments had either no nitrogen fertilizer or one of two levels of added nitrogen. Precipitation levels varied widely: The spring of 2011 saw record rainfall, but the spring of 2012 was one of the driest on record.

The results showed that while fall fires did reduce purple threeawn production, summer fires were much more effective, particularly after a wet spring. In comparison to the control plots, the weed's overall biomass was reduced 90 percent by the summer fire and 73 percent by the fall fire after the wet spring, and 73 percent by the summer fire and 58 percent by the fall fire after the dry spring.

The results were published in Rangeland Ecology and Management and in Fire Ecology in 2013.

Read more about this research in the April 2014 issue of Agricultural Research magazine.

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USDA Research Shows Potential Impact of Climate Change on Rangeland Plants

USDA Agricultural Research Service - Wed, 04/23/2014 - 11:26
USDA Research Shows Potential Impact of Climate Change on Rangeland Plants / April 23, 2014 / News from the USDA Agricultural Research Service

 Cattle grazing on rangeland. Link to photo information
Warming temperatures and elevated carbon dioxide levels associated with global climate change can also extend the growing season of some of Colorado's arid grasslands, according to a new study in Nature co-authored by ARS scientists and their colleagues. Photo courtesy of Julie Kray, ARS.


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USDA Research Shows Potential Impact of Climate Change on Rangeland Plants

By Ann Perry
April 23, 2014

WASHINGTON—U.S. Department of Agriculture (USDA) scientists and their colleagues have conducted research showing the potential response of rangeland plants in arid regions of the United States to the conditions that will occur with climate change, according to a paper published today in Nature.

Agricultural Research Service (ARS) biological technician Melissa Reyes-Fox and Fort Lewis College assistant professor Heidi Steltzer were the lead co-authors on the paper. ARS is USDA's chief intramural scientific research agency, and the research supports the USDA priority of responding to climate change.

"Agricultural producers want to know how global climate change is affecting their production and management practices," said ARS Administrator Chavonda Jacobs-Young. "This work is one example of how ARS scientists are helping producers meet climate change challenges and continue the cost-effective and environmentally sustainable production of food and feed."

In a 5-year investigation, the researchers assessed the effects of increased temperatures and carbon dioxide levels on plants growing in a native mixed-grass prairie. For their study, they used a field system called Free-Air CO2 Enrichment to elevate current levels of carbon dioxide to 600 parts per million, the level of atmospheric carbon dioxide that is expected in the latter half of this century. Outdoor heaters in the fields kept air temperatures at current levels and at day and night temperatures that were 2.7 and 5.4 degrees Fahrenheit warmer than ambient temperatures.

The scientists tracked leaf emergence, flower production, seed maturation, and canopy senescence in four grasses, a shrub, and a forb common to northern mixed-grass prairie plant communities. The resulting yearly data trends indicated that the plants responded to warmer temperatures with earlier leaf emergence and flowering. Some species also responded with earlier seed maturation and canopy senescence. On average, the growing season for plant communities exposed to higher temperatures began five days earlier and lasted six days longer.

However, when plants were exposed to a combination of warmer temperatures and elevated carbon dioxide levels, the growing season began seven days earlier and lasted 14 days longer. The researchers believe that elevated carbon dioxide levels prompt greater water conservation in some of the grassland plants, which in turn delayed early plant senescence and death.

A plant community gets a jump-start on its growing season when the first species leafs out earlier in the spring, and the growing season continues until the last species enters senescence in the fall. So while warming temperatures can increase the length of the growing season in some grasslands communities by promoting earlier spring growth, elevated carbon dioxide levels can help plants conserve water and delay fall senescence.

Other ARS scientists in Fort Collins who contributed to the study included agronomist Gregory McMaster, who works in the Agricultural Systems Research Unit; plant physiologist Dan Lecain and ecologist Dana Blumenthal, who work in the Rangeland Resources Research Unit; and retired plant physiologist Jack Morgan. Colorado State University professors M.J. Trlica (retired) and Allan Andales also contributed to the research.

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Some Cows' Infertility Linked to Y Chromosome

USDA Agricultural Research Service - Mon, 04/21/2014 - 06:59
Some Cows' Infertility Linked to Y Chromosome / April 21, 2014 / News from the USDA Agricultural Research Service
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 Two cows and calf in a field. Link to photo information
ARS scientists have found that one reason why some beef cows may not be getting pregnant is they have fragments of male Y chromosome in their DNA. Click the image for more information about it.


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Some Cows' Infertility Linked to Y Chromosome

By Sandra Avant
April 21, 2014

One reason why some cows cannot get pregnant may be because they have male (Y) chromosome fragments in their DNA, according to a U.S. Department of Agriculture (USDA) study.

Reproductive efficiency is the most economically important trait in cow-calf production. When a cow does not produce a calf, the producer does not make a profit, but still has to pay for feed, labor and other expenses.

With the help of beef producers, Agricultural Research Service (ARS) geneticist Tara McDaneld and her colleagues at the agency's Roman L. Hruska U.S. Meat Animal Research Center (USMARC) in Clay Center, Neb., examined reproduction data on about 6,400 females from cattle herds in Colorado, Florida, Nebraska and at USMARC. The team, which included molecular biologist John Keele and geneticist Larry Kuehn, then genotyped the animals, using a cost-saving genetic screening method called DNA pooling, which combines DNA from individual animals into a single pool.

Females usually inherit an X chromosome from each parent (XX), while males inherit an X and a Y (XY). In the study, only females were tested. Researchers found fragments of the male Y chromosome only in the pool of DNA from non-pregnant animals. All the results should have been XX among the females, according to McDaneld.

To verify their findings, scientists used an additional test called polymerase chain reaction (PCR), which is an inexpensive and effective means to identify fragments of the Y chromosome. Among animals with low reproductive efficiency, the PCR study showed that 25 percent of those females in the Florida population and 20 percent in the USMARC group had at least one significant chromosome-Y genetic marker. None of the highly reproductive animals had these markers, indicating that females were not getting pregnant because they carried Y chromosome segments.

USMARC scientists are the first to identify the occurrence of chromosome-Y genetic markers in beef cows with reduced reproductive capacity.

Read more about this research in the April 2014 issue of Agricultural Research magazine.

ARS is USDA's principal intramural scientific research agency, and this research supports the USDA priority of promoting international food security.

Categories: USDA

USDA Researchers Simplify Pyrolysis Processes for Bio-oil Production

USDA Agricultural Research Service - Thu, 04/17/2014 - 07:14
USDA Researchers Simplify Pyrolysis Processes for Bio-oil Production / April 17, 2014 / News from the USDA Agricultural Research Service
Read the magazine story to find out more.

 Two bottles of pyrolysis oil, one being poured into a glass dish. Link to photo information
ARS scientists have patented a new pyrolysis process that is more cost-effective at turning wood chips and switch grass into bio-oil, which can be used as a "drop-in" substitute for conventional fuels. Photo courtesy of Warren Gretz /National Renewable Energy Laboratory.


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USDA Researchers Simplify Pyrolysis Processes for Bio-oil Production

By Ann Perry
April 17, 2014

Innovations at the U.S. Department of Agriculture (USDA) are bringing researchers one step closer to developing "green" biofuel production systems farmers can use to meet on-farm energy needs, or to produce renewable fuels for commercial markets. These findings by Agricultural Research Service (ARS) scientists Charles Mullen and Akwasi Boateng promote the USDA priority of finding new bioenergy sources. ARS is USDA's chief intramural scientific research agency.

Fast pyrolysis is the process of rapidly heating biomass from wood, plants and other carbon-based materials at high temperatures without oxygen. Using pyrolysis to break down tough feedstocks produces three things: biochar, a gas, and bio-oils that are refined to make "green" gasoline.

The bio-oils are high in oxygen, making them acidic and unstable, but the oxygen can be removed by adding catalysts during pyrolysis. Although this adds to production costs and complicates the process, the resulting bio-oil is more suitable for use in existing energy infrastructure systems as a "drop-in" transportation fuel that can be used as a substitute for conventional fuels.

In 2013, the ARS team filed a patent application for a new pyrolysis process called Tail Gas Reactive Pyrolysis (TGRP), which removes much of the oxygen from bio-oils without the need for added catalysts. The team conducted a pilot-scale study using three types of biofeedstock with different characteristics: oak, switchgrass, and pressed pennycress seeds.

The researchers modified the standard pyrolysis process by gradually replacing nitrogen gas in the processing chamber with the gases produced during pyrolysis. The TGRP process was very effective in lowering oxygen levels and acidity, and no additional catalysts were needed.

Bio-oils produced from oak and switchgrass by the new process had considerably higher energy content than those produced by conventional fast pyrolysis. The energy content of the oak bio-oil was 33.3 percent higher and contained about two-thirds of the energy contained in gasoline. The energy content for switchgrass was 42 percent higher, slightly less than three-fourths of the energy content of gasoline.

The scientists, who work at the ARS Eastern Regional Research Center in Wyndmoor, Pa., published results from their research in 2013 in Energy & Fuels.

Read more about this research in the April 2014 issue of Agricultural Research magazine.

Categories: USDA

New Ornamental Tung Tree Available

USDA Agricultural Research Service - Mon, 04/14/2014 - 06:08
New Ornamental Tung Tree Available / April 14, 2014 / News from the USDA Agricultural Research Service
Read the magazine story to find out more.

 Blooms of Anna Bella, a late-flowering ornamental variety of the tung tree (Vernicia fordii). Link to photo information
ARS has released Anna Bella, the first ornamental tung tree that produces virtually no nuts, which are toxic if ingested and pose a mowing hazard if left on the ground. Click the image for more information about it.


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New Ornamental Tung Tree Available

By Jan Suszkiw
April 14, 2014

Anna Bella may herald a new generation of ornamental tung tree varieties suitable for landscape uses in the U.S. Gulf Coast region.

According to U.S. Department of Agriculture (USDA) molecular geneticist Timothy Rinehart, Anna Bella marks a first in ornamental tung releases because it is sterile and produces virtually no nuts, which are toxic if ingested and pose a mowing hazard if left on the ground.

From the late 1920s to early 1970s, tung trees had been grown commercially on plantations across the Gulf Coast area as a nut-based source of high-quality oil for paints, varnishes, lacquers, wood finishes and other industrial products. A convergence of factors ultimately scuttled the tung oil industry there, but nostalgia for Vernicia fordii, as the native Chinese tree is known scientifically, has lingered to this day.

The downside to planting tung as an ornamental has been the nuts, which are no longer harvested for their oil, notes Rinehart, with the Thad Cochran Southern Horticultural Research Laboratory operated in Poplarville, Miss., by the Agricultural Research Service (ARS). ARS is USDA's chief intramural scientific research agency.

Anna Bella, which is adapted to conditions in the South, can reach nearly 40 feet tall and opens into an umbrella-shaped canopy of lush, heart-shaped leaves. It blooms in late spring, producing clusters of white, long-lasting flowers tinged in the centers with yellow or red. The new variety requires little maintenance, bounces back well from pruning, and can withstand common insect pests and diseases.

It is ideal for both single specimen and row plantings, such as in backyards and along roadsides or property boundaries. Because it produces no seed, the variety is unlikely to persist beyond intended planting sites, a characteristic that may encourage wider acceptance of the tree species as an ornamental offering.

Rinehart has already received requests from a few specialty nurseries interested in propagating the variety.

Read more about this research in the April 2014 issue of Agricultural Research magazine.

Categories: USDA

On the Trail of Fire Ant Pheromones

USDA Agricultural Research Service - Fri, 04/11/2014 - 05:52
On the Trail of Fire Ant Pheromones / April 11, 2014 / News from the USDA Agricultural Research Service
Read the magazine story to find out more.

 Fire ants. Link to photo information
ARS scientists have found blocking a fire ant neuropeptide that triggers the pheromone used to mark food trails through a technique called RNA interference (RNAi) can delay development or kill fire ants, marking it as a potential control method. Click the image for more information about it.


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On the Trail of Fire Ant Pheromones

By Sandra Avant
April 11, 2014

U.S. Department of Agriculture (USDA) scientists are developing innovative techniques to combat one of the world's worst invasive species, the red imported fire ant.

In the United States, fire ants cost $7 billion in control, damage repair and medical care each year. They infest millions of acres in urban, agricultural, wildlife, recreational and industrial areas.

Scientists at the Agricultural Research Service (ARS) Center for Medical, Agricultural and Veterinary Entomology in Gainesville, Fla., are investigating chemicals called pheromones that are secreted by the ants. Pheromones signal alarm, mark trails to food, attract workers to brood and the queen, and unite males and females for mating.

Entomologist Man-Yeon Choi and chemist Robert Vander Meer at the Gainesville center have shown for the first time that a neuropeptide called pheromone biosysnthesis activating neuropeptide (PBAN) activates production of trail pheromones in ants.

PBAN was first discovered by ARS scientists in Beltsville, Md., in the 1980s. They found that the hormone regulates sex pheromone production in female moths. Since then, scientists have found that other insects, including cockroaches, have this type of PBAN family peptides made of two or more amino acids.

Choi injected fire ant workers with PBAN peptides and found a significant increase in pheromone production. He and Vander Meer also identified the DNA sequence of both the PBAN gene and receptor gene, which allowed them to test the function of PBAN in trail pheromone production using a new technique called RNA interference (RNAi). This involves taking normally single-stranded RNA from a gene and making double-stranded RNA (dsRNA) that can be used to suppress that gene's expression.

When scientists injected dsRNA of either the PBAN gene or receptor gene into ants, they found that ants produced less trail pheromone. They also discovered that adult ants and larvae injected with PBAN-RNAi had significant mortality, compared to ants that didn't receive the injection. Pupae that received the treatment had delayed development and a high death rate.

Scientists plan to investigate whether other pheromones are activated by PBAN, and if dsRNA can be used for fire ant control.

ARS is USDA's principal intramural scientific research agency.

Read more about this research in the April 2014 issue of Agricultural Research magazine.

Categories: USDA

Looking to Wheat's Wild Ancestors to Combat an Evolving Threat

USDA Agricultural Research Service - Mon, 04/07/2014 - 05:23
Looking to Wheat's Wild Ancestors to Combat an Evolving Threat / April 7, 2014 / News from the USDA Agricultural Research Service
Read the magazine story to find out more.

 Einkorn wheat head
ARS scientists have found a gene in einkorn wheat, an ancient variety still cultivated in parts of the Mediterranean, that appears to offer near immunity to Ug99, a stem rust that is a serious threat to 90 percent of the world's wheat. Photo courtesy of Matthew Rouse, ARS.


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Looking to Wheat's Wild Ancestors to Combat an Evolving Threat

By Dennis O'Brien
April 7, 2014

U.S. Department of Agriculture (USDA) scientists have pinpointed the location of a gene in a little-known ancient grass that could help save one of the world's most important cereal crops from an unrelenting fungus.

Agricultural Research Service (ARS) scientists Matt Rouse and Yue Jin, with the agency's Cereal Disease Research Laboratory in St. Paul, Minn., found the gene while studying the DNA of ancient grasses. They were searching for genes that could make wheat more resistant to Ug99 (Puccinia graminis), a type of stem rust that is constantly evolving. ARS is USDA's principal intramural scientific research agency, and this work supports the USDA priority of promoting international food security.

Ug99 has not yet been found in the United States, but it is spreading overseas and is considered a potential threat to up to 90 percent of the world's wheat. Genes in wheat that seem to offer immunity one growing season become susceptible to newly developed "races" the next. Ug99 was first reported by scientists in Uganda in 1999, and controlling it has since become an international priority.

Scientists often study a crop's wild relatives for genes that will confer resistance to pests and pathogens. But what makes the efforts of Rouse and Jin noteworthy is the diversity of grasses being studied. They include einkorn wheat, an ancient variety still cultivated in parts of the Mediterranean; emmer wheat, found in archeological sites and still growing wild in the Near East; and goatgrass, a wild relative of wheat with genes that breeders have tapped to boost immunity in commercial wheat varieties.

In one study, Rouse and his colleagues at Kansas State University and the University of California at Davis focused on locating a gene in einkorn wheat that confers near immunity to Ug99. They focused on locating a gene, known as Sr35, which was previously discovered in einkorn. But the exact location of this gene in the plant's vast genome remained a mystery. The wheat genome is huge, containing nearly two times more genetic information than the human genome.

To find Sr35's position, the researchers sequenced areas of the plant's genome where they suspected it was located. In one set of mutant plants, they knocked out the cloned sequences and found it made those plants susceptible to Ug99. In another set they inserted the same sequences into previously susceptible plants and found it made them resistant.

The results, published in Science in 2013, marked the first time that scientists managed to isolate and clone a Ug99 resistance gene. The achievement should make it easier to insert useful genes into wheat varieties.

Categories: USDA

Scientists Develop New Way to Make Food Ingredient from Rice Bran Oil

USDA Agricultural Research Service - Thu, 04/03/2014 - 07:14
Scientists Develop New Way to Make Food Ingredient from Rice Bran Oil / April 3, 2014 / News from the USDA Agricultural Research Service
Read the magazine story to find out more.

 A loaf of white bread, baked with rice bran oil extract, cooling on a rack. Link to photo information
ARS scientists have developed a very low temperature process to make a shelf-stable nut-butter-like extract from rice bran oil as a trans fat free replacement for some of the margarine, butter or shortening in certain baked goods. Click the image for more information about it.


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Scientists Develop New Way to Make Food Ingredient from Rice Bran Oil

By Marcia Wood
April 3, 2014

Some of today's popular baked goods might tomorrow contain a butter-like extract, derived from rice bran oil, as a partial replacement for margarine, butter or shortening. U.S. Department of Agriculture (USDA) chemist Erica L. Bakota and her colleagues with USDA's Agricultural Research Service (ARS) in Peoria, Ill., developed a process for making the extract, which somewhat resembles a nut butter.

The product's texture and composition are apparently unique, according to Bakota.

In preliminary experiments at the ARS National Center for Agricultural Utilization Research in Peoria, Bakota and her colleagues used the extract in place of some of the butter called for in standard recipes for granola and for white bread. Feedback from taste testers who participated in these preliminary experiments indicated that the substitutions did not detract from the taste or texture of either the granola or the bread.

Unlike some shortening and margarines, the extract is free of trans fats, which contribute to increased risk of heart disease. Another plus: The product is shelf-stable and resists oxidation that could otherwise result in off-flavors and unpleasant odors.

The extract consists primarily of unrefined rice bran oil and rice bran's natural wax, which is used in confections. It also contains minor amounts of vitamin E; plant sterols, including some that are of interest to medical and nutrition researchers because of their potentially health-imparting properties; and gamma-oryzanol, shown to lower levels of "bad" LDL cholesterol in humans.

The Peoria team's extraction procedure evidently differs from other approaches for making a butter-like product from rice bran oil in that it uses very low temperatures. ARS, the USDA's chief intramural scientific research agency, is seeking a patent for the procedure. Bakota is looking for collaborators interested in developing new uses for the product.

A staple at Asian food markets or other specialty or gourmet grocery stores, rice bran oil has a mild flavor and is high in vitamin E, an advantage that many other well-known cooking oils don't offer. The oil comes from the outer layers that are removed when rice grains are milled and polished to produce white rice.

Bakota and teammates Michael J. Bowman, Hong-Sik Hwang, Sean X. Liu, Debra L. Palmquist, and Jill K. Winkler-Moser, all with ARS at Peoria, described the research in a 2013 article published in the European Journal of Lipid Science and Technology, and in a new article accepted for publication in that journal. The studies are highlighted in the April 2014 issue of Agricultural Research magazine.

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