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It's known that chilly evenings can cause biochemcial chaos in
warm-weather plants like tomatoes and corn, resulting in reduced
yields. But ARS researchers say that manipulating certain plant
enzymes could keep crop biochemistry on an orderly schedule. If the
researchers succeed, the same tactic may also expand the geographic area
in which some warm-weather plants are grown. Crucial processes that
normally take place at night in the plant may shut down when temperatures
dip below 50 degrees F. When the weather warms up in the morning, the
nighttime processes resume. But they may clash with different, but
equally important processes set to occur during the day. ARS researchers
have determined that the two enzymes play a key role in turning on and off
central biochemical activities. Their aim is to manipulate the enzymes
sucrose phosphate synthase and nitrate reductase to override nature's
obsession with temperature.
Photosynthesis
Research Unit, Urbana, IL
Don Ort, (217) 333-2093
Growers will soon have four new selections of commercially available
blueberries to choose from. Little Giant--bred for the cooler
climates of Washington, Oregon, Michigan, New Jersey and North
Carolina--offers an alternative variety for frozen and processing markets,
and should be planted with other northern highbush blueberry varieties for
cross pollination. Pearl River, Magnolia, and Jubilee are new varieties
and more suited to the warmer climates in the Gulf Coast and Southeastern
United States. They should be interplanted with other southern highbush
blueberry varieties to ensure fruit set, early ripening and maximum yield.
Each of the four new varieties is productive and disease resistant.
Plants are available in season at nurseries.
Blueberry & Cranberry Research Center, Chatsworth, NJ
Mark K. Ehlenfeldt, (609) 726-1590
Small Fruit
Research Station, Poplarville, MS
James M. Spiers, (601) 795-8751
Two new June-bearing strawberries have been introduced by ARS plant
breeders for the Middle Atlantic and adjacent regions. Primetime, a
mid-season berry, bears fancy, good quality, large fruit. Latestar, a
late-season variety, has large, attractive fruit. Both varieties are
recommended for shipping and local markets and resist multiple fungal
diseases. They produce well on either light or heavy soils, and in matted
rows or in hill culture. Plants are available in season at nurseries.
Fruit Laboratory,
Beltsville, MD
Gene Galletta, (301) 504-5652
Potato farmers could save on fertilizer--and cut yield losses from a
fungus--by rotating their potato crops with one of these nitrogen-fixing
legumes: hairy vetch, alfalfa or white lupin. ARS scientists
conducted a two-year field study with the legumes. Maine potato farmers,
who typically don't use cover crops, must apply 120 to 200 pounds of
nitrogen fertilizer per acre, depending on the potato variety. But the
researchers showed that planting one of the legumes allows reducing the
rate without sacrificing yield. Legumes take nitrogen from the air and
store it in nodules on their roots. After the legumes die and their roots
decay, the next potato crop can use this nitrogen for growth. In the ARS
study, hairy vetch replaced nearly 60 pounds of nitrogen fertilizer per
acre; alfalfa, about 40 pounds; and lupin, 20 pounds. The study also
revealed that growing a legume disrupted the life cycle in the soil of a
Rhizoctonia fungus, the culprit behind yield-damaging
lesions on potato plant stems. When one potato crop followed another,
nearly 60 percent of the plant stems had lesions. Rotating potato with
alfalfa cut this to 12 percent.
New England Plant, Soil and Water Laboratory, Orono, ME
C. Wayne Honeycutt, (207) 581-3363
Sugarbeet breeders can now get two new ARS-developed sugarbeet lines
that combine resistance to the three diseases that cause nearly all
disease damage to beets worldwide. Resistance of both new lines is
excellent against Rhizoctonia root rot, and moderate
against curly top and Cercospora leaf spot. Individual commercial
varieties may be highly resistant to one or another of the three diseases.
But the new lines--named FC721 and FC721CMS--contain better resistance
against an onslaught of all three diseases. ARS and the Beet Sugar
Development Foundation jointly released the lines after testing by ARS
researchers in Fort Collins, CO, and Kimberly, ID. Commercial breeders
can obtain seed from ARS.
Crops Research Laboratory, Fort Collins, CO
Lee Panella, (970) 498-4230
A commercially available insect growth regulator, fenoxycarb, works on
a number of different insects, including fire ants, cockroaches and
caterpillars in a variety of agricultural, range and urban habitats.
Now the compound is being used to control pear psylla, the most severe
insect pest of pears in the Pacific Northwest. In orchard tests in 1995,
ARS scientists found that a single application in mid-March killed up to
half the pear psylla eggs and reduced densities of second generation
psylla below damaging levels. Because fenoxycarb appears to have much
less of an effect on natural enemies, it also allowed a slow buildup of
predators and parasites. But its effectiveness was reduced during 1996
because of a cool spring and two applications were needed. In both years,
trees not sprayed with fenoxycarb had extremely high pear psylla
infestations, requiring summer applications of insecticides. Scientists
are helping growers incorporate the technique into a large, area-wide,
integrated pest management program aimed at reducing insect problems while
reducing insecticide use.
Fruit and Vegetable Insect Laboratory, Wapato, WA
David R. Horton, (509) 454-6550
Wild species of sunflowers might provide their cultivated cousins with
genes for such valuable traits as drought tolerance or disease
resistance. Until recently, embryos of most crosses between
cultivated sunflowers and wild species wouldn't develop into fertile
plants. Now scientists have broken the interbreeding barrier for at least
nine difficult-to-cross species by first growing a meager portion of the
hybrid embryos on a new tissue-culturing medium. Then the researchers
treat the "rescued" embryos with the chemical colchicine to double the
number of chromosomes in reproductive cells. Plants called amphliploids
are produced from these male and female reproductive cells with doubled
chromosomes. These amphliploids of interspecies hybrids are genetically
compatible with other sunflowers used in breeding experiments.
Oilseeds Research, Fargo, ND
C.C. Jan, (701) 239-1319
A new irrigation aid automatically blocks unwanted surges in water
pressure to help farmers avoid applying too much water to their crops.
An ARS scientist invented and patented the lightweight, low-maintenance
irrigation pressure regulator. It can easily be installed in several
kinds of pressurized irrigation systems, including buried drip or surface
drip and lateral move or center pivot sprinklers. Key components of the
new device are an air cylinder and spring that close a butterfly valve in
the irrigation pipe when water pressure exceeds the target set by the
grower. The regulator is simpler and cheaper than some other options for
controlling water pressure. It could prove ideal for some of the 11
million acres of irrigated farmland in the United States that are hilly
enough to warrant pressure control valves. The apparatus is appropriate
for pipes or conduits that measure two to 12 inches in diameter, carry
flows of 25 to 2,500 gallons per minute, and handle pressures of 5 to 90
pounds per square inch. A computer spreadsheet program from ARS assists
valve manufacturers or irrigation system designers in calculating the
correct size and settings for the spring and cylinder. (PATENT
5,509,449)
Northwest Irrigation and Soils Research Laboratory, Kimberly, ID
Dennis C. Kincaid, (208) 423-6503
Seed testers should monitor the water temperature when judging the seed
quality of winter wheat and other plants. The temperature of the
water that moistens a sample of planted seed may be more important than
previously thought. ARS scientists have discovered important exceptions
to the general rule that crops germinate and grow best after planted seeds
absorb water at 68 to 86 degrees F. These temperatures turned out to be
detrimental to germination and seedling growth of winter wheat and
rangeland shrubs like sagebrush and kochia. These plants do better when
seeds soak up water at 41 to 59 degrees. Research also showed that age of
the seed affects optimal water temperature. For winterfat, old seed
showed increased vigor at cooler water temperatures. Based on
observations of 11 crop and shrub species, scientists recommend that
guidelines be developed for each important plant species. The guidelines
would be incorporated into seed testing procedures recommended by the
Association of Official Seed Analysts, International Seed Testing
Association and similar organizations charged with seed quality
testing.
High Plains Grasslands Research Station, Cheyenne, WY
D. Terrance Booth, (307) 772-2433
Last updated: October 22, 1996
Return to: Quarterly Report
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