Agricultural research

26 Pages·1993·3.2 MB·English

by  United States. Science and Education Administration

Archive Document
Historic,
Do assume
not content reflects current
scientific knowledge, policies, or practices.

.
FORUM
The Miracle Crop Just Keeps soybeans' potential as a cash and feed crop and proclaimed
soybeans 'The New Iowa Dollar."
on Growing
In the 1927 Yearbook ofAgriculture, Secretary of
Like the old farm saying about utilizing every part ofa Agriculture W.M. Jardine had this to report to the President
pig but its squeal, soybeans have found their way into an and to the farmers he hoped would be the chiefbeneficia-
eye-opening array ofproducts, edible and otherwise. ries ofthe book:
—
Starting with the basics in nutrition, there's milk not "During the past year many new varieties ofsoy beans
cow's milk, but soy milk. In the United States, soy milk is have been received from our agricultural explorers. . .
used in infant formulas, and it's stocked in health food The adaptability ofthe soy bean to new conditions is well
stores as well. illustrated by the Virginia variety. In the Ozark region of
Soy milk plays an even more important role in human Missouri, extensive tests failed to show any promising
nutrition in other parts ofthe world. In China, it's called tou sorts undl the Virginia was tried and found to succeed
chaing, and cafes there that specialize in this beverage often admirably on the less fertile Ozark soils. The range oflocal
have an open pot ofboiling tou chaing in front ofthe shop adaptability is extensive and the study of varieties must be
to lure customers, in much the same way sizzling onion bits carried on over a wide territory."
on a grill make mouths water on a carnival midway. More than 65 years later, farmers still strive to plantjust
A soybean food product that's probably more familiar to the right variety ofsoybean for a specific setting, even to
the average American consumer is tofu, soybean curd the extent ofplanting beans ofvarying maturity dates at
made by coagulating soy milk. Far from beingjust a fad, different locations in a single state.
— —
tofu also spelled tou fu dates back many centuries. One But science is working to manipulate the soybean in
popular recipe for preparing tofu was developed by Liu more sophisticated ways. At one ARS laboratory at
An, King ofWainan, sometime between 179 and 122 B.C. Beltsville, Maryland, scientists have cloned genes for
Today, there are also soy yogurt, soyburgers, soy loaf, proteins in soybeans, with an eye to improving the quality
and soy sausage. Soy oil is the most widely used edible oil ofthe beans' oil.
in the United States; you can find it in mayonnaise, salad The scientists want to pinpoint what turns these genes
dressing, whipping cream, and dessert frostings. Soy on and off, since they prompt production ofthe proteins
components such as protein and oil are ingredients in which, in turn, are involved in production and packaging of
—
dozens ofeveryday foods from the granola bar at the oil inside the bean. The researchers also want to know
breakfast and the p—otato chips at lunch, to a late-night how factors such as drought and heat stress affect the
snack of ice cream and it's almost impossible to find a activity ofthe genes.
chocolate treat minus soy lecithin. At another Beltsville lab. ARS scientists are studying
Thanks to research by ARS scientists, soybeans have the gene that controls when soybean plants shed their
been incorporated into many common nonfood products flowers, frequently in response to drought or other stresses.
ranging from the morning newspaper printed with soy oil- Fewer flowers mean fewer beans.
based ink to cleaners capable of lifting grease, catsup, The gene in question orders cells to make an enzyme
mustard, ink, lipstick, and mascara stains from fabric. It's called cellulase. Flowers i\re shed when cellulase dissolves
difficult to imagine a day without soybeans. the biochemical glue between a single la\er of stem cells
But soybeans actually got offto a slow start in the and cells of the departing flower. The researchers hope to
United States. Although they airived here in the mid- find the part of the gene that acts as its "on-off' switch.
1700's, they didn't really catch on until the 1920's. The world is a much different place from the days w hen
Demand for soy products was already on the rise: The soybeans were touted as the Miracle Crop. But one thing
United States imported 23.5 million pounds of soybean oil hasn't changed: There are still plenty of scientific paths to
in 1927. But farmers were still cautious about trying this explore on the way to achiex ing soybeans" full potential.
new crop. At that year's Tama County (Iowa) fair, first
prize for an exhibit went to a display that promoted Sandy Miller Hays
ARS
Information Staff
All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without
regard to race, color, national origin, religion, sex, age, marital status, or handicap.
2 Agricultural Research/October 1993
Agricultural Research
Sometimes called The SoybeanDoctorin deference to his plant-breedingsuccesses, agrono-
mist EdgarE. Hartwighas devoted halfa century to soybean research. His focus has been on
developingproductive plants with built-in resistance toinsects, nematodes,and diseases. Heis
bestknownforcommercial varieties thatinclude Bragg, Lee,Forrest, Lamar, Sharkey, and
most recently,Vernal. Photo by KeithWeUer. (K5272-1)
4 To Build a Better Soybean
Researchers tackle both above- and below-ground production problems
in their pursuit of the perfect bean.
12 Streams of Conscientiousness
Page 14 IVIinor adjustments in erosion-control structures and practices are leading
to the renewal of waterways and resurgence of fish populations.
18 Trasli to Treasure: Recycling Waste Paper
As the nation's landfills close, agriculture may offer badly needed
alternatives for disposing of this abundant and potentially valuable
commodity.
22 Catfish Fillets Checked for Flavor
A new, objective rancidity measurement can help processors improve
Page 18 quality monitoring and evaluation of packaging and handling innovations.
23 Science Update
Page 22
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Agricultural Research/October 1993 3
Scientists
still
>V
£/
c^^O
aren't through
tinkering with this
newcomer crop
r
now second
that's
only to corn in
importance to U.S.
farmers.
SCOTT BAUER(K5269-7)
oybeans can be found today, ofjust one. They are having some suc- Just as mile markers can tell you
in one form or another, in a cess in increasing yields without affect- where you are on a highway, these
wide array offood and in- ing protein. genome maps can tell a scientist where
dustrial products. But until Burton has now completed six 2- to find the genes responsible for
the early 1900's, soybeans were virtu- year cycles in which 200 promising economically important traits such as
ally unheard ofin the United States. genotypes are planted in each oftwo the protein and oil contents ofthe
Those grown here were used as forage locations. The best-yielding 10 percent, soybean seed.
or as green manure to enrich the soil. which also have higher seed protein These are both quantitative traits.
Much ofthe credit for creating a concentrations, are then interbred and Shoemaker explains, which means that
commercial market for soybeans is replanted. Using statistical analysis of more thanjust a single gene determine
given to A.E. Staley, who, in 1922, seed yield and protein content, the the levels produced. So scientists are
modified his com processing plant in scientists have developed an index for using molecularprobes that distinguish
DNA
Decatur, Illinois, and announced that evaluating subsequent genotypes for specific fragments of to identify
he would buy all ofthe soybeans that the two desired the genes responsi-
KEITH WELLER
could be grown. characteristics. ble for the protein
Today, Staley would have his hands "In past years, and oil content.
full: U.S. farmers in 1992 produced we've had yields Genetic maps
nearly 2.2 billion bushels ofthis versa- that were only 5 will allow breeders
tile crop on more than 62 million acres percent less than to identify key genes
in 26 states. Young, a currently that will, in turn,
"As the potential uses for soy-based planted commercial help them success-
products increase, there is a desire to soybean variety, but fully combine multi-
breed new soybean varieties to meet with about a46- ple traits to make
specific market needs," says Howard J. percent protein lev- advances much
Brooks, associate deputy administrator el," Burton says. more quickly.
ofplant sciences for USDA's Agricul- Potential markets Thus far. Shoe-
tural Research Service. for high-protein maker and col-
Whether it's increasing yields, varieties include the leagues have
breeding plants that are genetically re- animal feed industry mapped five of
sistant to pests, or boosting protein and and producers of seven genes respon-
ARS
oil levels in soybeans, researchers soy-based food for sible forresistance/
throughout the country have a signifi- human consumption susceptibility to
cant hand in soybean production. ARS plantpathologistGregNoel (left) different races of
For agronomist Joseph Burton at the Mapping and professor Cecil Nickell, University phytophthora root
ARS Soybean and Nitrogen Fixation Soybeans' Future ofIllinois, Urbana, evaluatesoybean rot, a disease that
roots for SCN resistance. (K5243-11)
Research Laboratory in Raleigh, North attacks the soy-
In the future,
Carolina, the goal is increasing the bean's vascular
making decisions to
protein content ofsoybeans without system and eventu-
guide soy breeding programs such as
decreasing yield. ally kills the plant. Phytophthora can
Burton's may be as simple as consult-
"Usually, when soybeans are bred in cost growers a tremendous amount of
ing a map.
an attempt to increase protein, total A team ofARS scientists at Ames, money in lost yields.
seed yield suffers," he says. "Using molecularprobes, we
Iowa, is mapping the soybean genome
Soybeans' normal protein level is analyzed six ofthe seven genes and
to determine the whereabouts ofthe
about 41 percent on a dry-weightbasis. were able to map five ofthem,"
genes on its chromosomes. Plant genet-
Burton has successfully upped this to Shoemaker says.
icist Randy C. Shoemaker says having
45.5 percent and is now working on the In Stoneville, Mississippi, scientists
such a map will "take some ofthe gam-
yield part ofthe problem. have found a new genetic source of
With a classical breeding approach ble out ofgenetics. resistance to phytophthorarot. A
"Breeders are tossing the dice every
using restricted index selection, scien- germplasm line that resists several
time they make a cross," he says. "We
tists are able to evaluate and select two races ofthe pathogen that causes the
want to stack the deck in our favor."
ormore traits simultaneously, instead
Agricultural Research/October 1993 5
—
disease was found in the USDA states, recently averaged more than mature and die, to form cysts. The cysts
Soybean Germplasm Collection at $85 million. are filled with eggs or hatchedjuve-
Urbana, Illinois. "In addition to cost savings to farm- niles. Thejuveniles penetrate plant
"This germplasm line contains a ers, the environment will benefit from roots and develop into adults in about a
gene to fight phytophthora rot that is less pollution ifthey don't have to use month. As they develop, the females
different from other genes currently pesticides," says Kilen. rupture the root surface.
being used by plant breeders to prevent The hunt for insect-resistant soy- The appearance ofyellow, stunted
the disease," says Thomas C. Kilen, beans has been ongoing for more than plants in an oval formation in the field
the geneticist in charge ofARS' Soy- two decades, he adds. usually signals that soybean cyst nema-
bean Production Research Unit at todes have reduced normal root nodula-
Stoneville. "It shows a resistance to Invisible Underground Attack tion and root growth.
some races ofthe pathogen that has not "Right now, the best way to fight
Warding off soil-borne nematodes is
been seen in other lines." this nematode is by crop rotation and
another important research goal.
Kilen has also found that the genes using resistant varieties," says plant
for phytophthora resistance and brown KEITH WELLER pathologist Gregory R. Noel ofthe
pod wall color are on the same chro- ARS Crop Protection Unit in Urbana.
mosome, but not closely hnked. By Plants may be infested with SCN at
selecting for pod wall color, breeders any time during the growing season,
may be able to indirecdy select for but the most devastating attacks occur
phytophthora root rot resistance. to 2 months after planting. While
1
"The benefits ofthis will be limited, chemicals are available to control the
though, since the genes are not closely pest, prohibitive costs generally limit
linked," Kilen says. "However, this their use.
knowledge will help further efforts to Some producers try to improve
map the soybean genome." yields ofSCN-stricken beans by inigat-
ing. But Larry G. Heatheiiy. an agrono-
Bad-Tasting Leaves mist at Stoneville, found that iirigation
during the soybean reproductive period
In other work at Stoneville, Kilen SCN
will not alleviate stress.
and coworkers have developed a new
"Growers with infested fields should
soybean with leaves that apparently
be discouraged from expending resour-
taste so bad that insects, given a
ces to iirigate those fields." he says.
choice, won't bite into them. But the —
Both germplasm soybean lines for
beans themselves are not altered, and —
use by breeders and fully developed
the oil and meal taste fine.
soybean vaileties with new sources of
Lavone Lambert, an entomologist at Roots infested with female soybean cyst SCN resistance ai^e being developed by
Stoneville, conducted studies that show nematodes (small round bodies); larger
the leaves and pods ofthis soybean round nodules contain beneficial nitrogen- Noel and University of Illinois soybean
fixing bacteria. (K5244-6) breeder Cecil Nickell.
plant contain a substance harmful to
Since 1982, seven new vaiieties and
insects, but not to humans or livestock.
ARS four germplasm lines have been re-
Mexican bean beetles, corn ear- Several scientists are sccirching
leased. Some were developed with
worms, velvetbean caterpillars, soybean for genes to incoiporate into soybeans
— cooperation IVoni the University of
loopers, and beet armyworms in fact, to better thwart Hetewdera glycines,
Missouri.
most major soybean insect enemies the soybean cyst nematode. There aie
do not fare well on the new variety. nine known SCN races, or types, in the Lawrence D. Young, a plant pathol-
ogist in the ARS Nemalology Rcseaich
Farmers may be able to save mil- United States.
lions ofdollars each year.Just by plant- This minute worm invades roots, Unit in Jackson, Tennessee, released
ing the bad-tasting, pest-resistant bean. disrupting the How of water and nutri- gemiplasm last yeai" that resists the race
2 nematodes that primarily infest soy-
Insect damage, in terms ofyield loss ents in the plants and reducing yields.
bean tlclds in Maryland and Tennessee.
and control costs in only nine southern Females are lemon-shaped and change
The new soybean line also shows vary-
in color from white to brown as they
6 Agricultural Research/Oclober 1993
DAVID NANCE
ing degrees ofresistance to other nem-
atode races.
"This hne has good productivity, but
the yield is not competitive with the
best cultivars," said Young. "Our idea
was to release the hne so commercial
breeders could cross it with their pro-
ductive lines and give them nematode
resistance."
Getting Enough Nitrogen
Like all hving organisms, the soy-
bean has specific needs that must be
met for it to thrive. Carbon dioxide,
sunhght, water, and nutrients are all
"musts" for ahealthy plant. Crops
generally get their supply ofnitrogen
from the soil, but the soybean has an-
other way to obtain this essential nutri- Undamaged soybean plantingeneticistThomas Kilen's lefthand demonstrates how effective
A insectresistanceis in this experimentalplant. (K5285-1)
ent. symbiotic nitrogen fixation sys-
tem located in the roots takes gaseous
possibihty ofgroundwater contamina- the Crops Research Laboratory, Fort
nitrogen from the air and converts it to
tion. Nodulation is also likely to get a Colhns, Colorado, have patented a
ammonium, a form usable by the plant.
boost from mutantB.japonicum mutant strain ofthe bacterium that
To accomphsh this, "A soil bacteri-
bacteria. L. David Kuykendall, a improves nitrogen fixation in soybeans
um known as Bradyrhizobiumjaponi-
microbiologist at the Beltsville (Mary- by increasing nodulation.
cum invades the roots and forms nod-
land) Agricultural Research Center and "In 2 years offield studies in Upper
ules," explains James E. Harper, the
W. James Hunter, a microbiologist at Marlboro, Maryland, we've obtained
plant physiologist in charge ofthe
Plant Physiology and Genetics Re-
search Unit at Urbana. "It's inside
these nodules that nitrogen fixation
takes place."
The bacteria obtain carbon com-
—
pounds ^primarily the common sugar
—
sucrose from the plant and return
nitrogenous compounds to it, as well as
to the soil.
Genetic selection has now pinpoint-
ed a mutant soybean Hne that has two
to fourtimes more nodules than the
average plant. Harper is attempting to
produce these extra nodules on a nor-
mal soybean root system to provide
more nitrogen to the plant andpossibly
release more nitrogen to the soil.
Increased nodulation may be good
news for farmers who plant com in
rotation after soybeans. It might allow
them to cut nitrogen fertiUzer apphca-
tions, reducing both costs and the
Agricultural Research/October 1993 7
a statistically significant 25-percent Illinois Soybean Program Operating "There may be genes in these vari-
increase in nodulation and a numeri- Board, and the Iowa Soybean Promo- eties to fight diseases and insects, and
cal increase in seed yield on plants tion Board were all partners in the to improve oil and protein content,"
inoculated with the new bacterium, as final agreement with the Chinese Nelson says, "but it will be a while
compared with another strain known Academy of Agricultural Sciences. before we really know what we have."
as USDA 1 10," says Kuykendall. Each will contribute $10,000 a year Once soybean seed is in the
Previously, USDA 10 was iden- for 2 years to cover expenses. ground, producers wage constant
1
tified as the best strain for use as an "The overall benefits of this ex- battles with nature.
—
inoculant a commercial product change will most likely be long- One fight is against weeds. Farm-
consisting of the bacterial cells plus a term," says Randall L. Nelson, cura- ers traditionally use herbicides and
peat-based carrier. tor of the Urbana soybean collection. tillage practices to control weeds.
Seed yield increases were also When Chen Yi Wu, a scientist However, Reid Smeda, a plant physi-
obtained in field tests conducted by from the Institute of Crop Germplasm ologist in the Weed Biology and
Urbana Laboratories in St. Joseph, Management Research Unit at
Missouri, and Fort Dodge, Iowa. Tom KEITH WELLER Stoneville, Mississippi, is looking at
Wacek, a microbiologist in charge of cover crops that exude toxic sub-
— —
research and development for Urbana stances allelochemicals as an
Laboratories, says the results are alternative method to fight weeds.
encouraging and promises more field "It's known that some cover crops
tests. can suppress weeds, but it's uncertain
how long the effect will last and how
New Germplasm, and Allelopathy the soybean crop will be affected,"
Smeda says.
If U.S. soybeans ofthe future are
In the initial year of testing, field
high-yielding and resistant to insects
plots were planted with sorghum-
and disease or have more nitrogen
sudangrass in early spring and killed
nodules than ever before, China may
using the herbicide glyphosate after
be at least partially responsible.
the grass grew 6 to 7 feet high. The
For the first time in history, the
glyphosate was applied to soybean
People's Republic of China has re-
leased a large quantity of soybean plots at a rate of 1 pound per acre 2
weeks, week, and day before
seed from its germplasm collection. I 1
The USDA Soybean Germplasm planting with a no-till drill. Crop
residue was flattened to minimize its
Collection at Urbana, Illinois, is the
interference with light received by
new home for the seed. Some 500 Plant physiologistJames Harper examines
emerging soybean plants.
accessions have been acquired, to mutant soybean with two to four times the
"Weed suppression was greater
date, and 500 more are expected root nodules ofaverage varieties. Nodules
contain nitrogen-fixing bacteria. (K5239-1) than 90 percent up to 60 days after
within the next year or so.
establishment." Smeda says. "And
It's all part of a two-way informa-
the soybean yields in plots where
tion exchange between the United
sorghum-sudangrass was killed
States and China. According to the I
Resources in Beijing, China, arrived week or day before planting were
agreement, the U.S. receives soybean I
in Urbana to work with Nelson, he within 2 bushels per acre yield of a
germplasm in exchange for the op-
brought with him seed from 500 soy- plot that had no cover crop and was
portunity for a Chinese scientist to
bean varieties gathered from 9 prov- hand weeded."
work side-by-side with an ARS sci-
inces in central China. Poor soybean gcrniinalion reduced
entist for a year and the provision of
Test plots planted and harvested in yields in the plot planted 2 weeks
new laboratory equipment for China.
1992 gave Nelson his first opportuni- after the cover crop was killed, al-
Discussions leading to this ex-
ty to analyze the new seeds. But with though weed suppression in this plot
change have been ongoing for nearly
just one growing season completed, was satisfactory. In an additional plot
10 years. ARS, the University of
the researchers are still uncertain of not planted with a cover crop, weeds
Illinois, Iowa State University, the
the benefits of these new accessions. were not managed. Yields from that
Agriculiuial Research/October 1993
8