Agricultural research

24 Pages·1992·3.3 MB·English

by  United States. Science and Education Administration

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Archive
Historic,
Do assume
not content reflects current
scientific l<nowledge, policies, or practices.

a
A
Blooming Industry
Poinsettias Lead the Way in Sales
Shops, homes, churches, and setti—a crop reached nearly $170 mil- whole industry to rest on generating most
hotels blossom with the rich lion ajump of more than 400 percent ofa year's income all in one short burst.
crimsons and scarlets ofpoin- from 1976. Developing that kind of depend-
settias as the winter holidays come The market has grown like this be- ability requires research that grow-
around each year. Outside may be cause it can depend—on having millions ers are rarely in a position to carry
Rorida's tender winter or Chicago's of poinsettias ready in long-lasting out. Discovering the exact condi-
—
blizzards, but indoors the showy, bril- bloom all at once. tions of light, temperature, and
liant colors ofthe poinsettia have be- Such dependability does not happen growing regimen requires the tightly
come the red in traditional Christmas by letting nature take its controlled conditions found
red and green—just as mums are the course. To be able to in laboratories and e—xperi-
emblem ofMother's Day and hlies a plan ahead to synchro- mental greenhouses and
symbol of Easter. nize the blooming of scientists able to spend
Last year, the
Not only is poinsettia the most pop- such masses ofplants years checking the effects
wholesale
ular Christmas plant, it is now the requires both precise of the smallest change.
number-one flowering potted plant in knowledge of the condi- value of the Since plants do not carry
the United States, even though its tra- tions that govern their poinsettia pedigrees, basic research and
ditional sales period isjust 6 weeks. growth and flowering crop reached breeding development are
But in 1959, the wholesale value of and the abihty to repeat rarely noted by the public.
nearly $170
poinsettias was a modest $8.9 million. those conditions year — But without such contribu-
—
In 1976, when Agricultural Research after year in other million tions, many flowers would
Service investigations hadjust begun words, scientific infor- jump of more never have become such
to blossom, the wholesale worth of mation. And it requires than 400 major sellers.
ARS
poinsettias was $37.6 million. Last plants genetically de- In particular. scien-
percent from
year, the wholesale value ofthe poin- pendable enough for a tists helped provide the sci-
1976.
PAUL ECKE
Commercial poinsettia production in California.
4 Agricultural Research/December 1992
Seasonal Symbol From Mexico
The poinsettia, a contemporary ofpurity because oftheir brilliant
symbol ofChristmas in many parts red color.
ofthe world, was introduced to the The Aztecs made a reddish-
United States and named after Joel purple dye from the colored "flow-
entific informa- Robert Poinsett in 1825. ers," which are actually modified From these, he
tion that helped Poinsett was serving as the first leaves called bracts. They also developed several
the poinsettia into
U.S. ambassador to Mexico when made a medicine against fevers from different varieties
the multimilhon- he saw the plant growing on the the latex sap ofthe plant. that looked beautiful
dollar industry it hillsides ofTaxco, a small town in In the 1600's, Franciscan priests and had staying
is today. southern Mexico, where the plant came to Taxco and began using power. "We had
ARS
research- is native. poinsettias in the Fiesta of Santa great names: Rudol-
ers performed Taxco was called Cuetlaxochitl Pesebre, which is a nativity proces- ph, for the reindeer.
breeding experi- by the Aztecs, who prized poinset- sion. The appearance ofthe red Ruff and Reddy;
hmeonwtscotlhoartddeevfeiln-ed tias and considered them a symbol bprraocctesssciooinn.c—ideJd. wKiitmh tKhaeptliamenofthe bSteopoluirgbhetswtansammea,y"-
ops in poinsettias, Stewart remembers.
and they devised To separate poin-
precision growing
settias genetically so
methods. the end ofa meeting, I'd notice all the that his breeding work wouldbe as pre-
"ARS contributions have been very leaves had dropped offthe plants." cise as possible, Stewart called on ARS
significant for the poinsettia industry," Poinsettias also held scientific inter- plant physiologist Sam Asen for help.
says Carolyn Mack, spokesperson for est for Stewart and other ARS scien- Asen identified and characterized
the Poinsettia Growers Association. tists because they are an "—excellent the pigments that give poinsettias their
"In particular, the cooperative efforts plant for testing purposes extremely distinctive colors, using what was then
of distinguished ARS researchers such useful in the laboratory," he says. a very new tool called a microspectro-
as Robert Stewart and Marc Cathey They are evolutionarily primitive photometer assembled by Karl Norris.
have been extremely helpful to the plants that cannot be crossbred with Norris was part ofthe ARS team
commercial hybridizers." other species. that found phytochrome, the plant
KIM KAPLAN This makes their pigment that serves as a biological
How It All Got Started physiology easier light switch controlling flowering and
In the 1950's, poinsettias would to study than that other plant functions. He developed
appear each year in hotel lobbies and ofcomplex, hy- the microspectrophotometer to mea-
other public areas shortly before brid plants. sure spectral (light refracting) proper-
Christmas. But those plants were ex- But poinsettias ties, which can identify chemical com-
pensive to produce and most kept their are also difficult ponents in a substance.
leaves and color only a few days. to work with be- "From that information, I was able
Then, Robert N. Stewart, atthe time a cause they pro- to develop fingerprints ofpoin—settias
geneticist in ARS' Florist and Nursery duce only one by quantifying their pigments a sort
Crops Laboratory in Beltsville, Maryland, seed for every of chemotaxonomy," Asen says.
became interested in improving poin- three breeding crosses, rather than He found that the pigments that
settias. (He has since retired.) many, like wheat or com. give poinsettias their characteristic
Stewart b—egan by looking at "keep- Most poinsettia propagation is done colors are anthocyanin-flavonoid com-
ing quality" ^the length oftime that from cuttings, and small cha—nges and plexes. The colors ofthese complexes
poinsettias will remain presentable. advances come from sports genetic are also greatly influenced by the acid-
"Most ofwhat growers produced be- aberrations or mutations. ity ofthe cells' vacuoles where the
fore I started working was beautiful Stewart found that most ofthe com- pigments reside.
when it left the greenhouse, but itjust mercial poinsettia varieties—grown in "Once we had these quantified, it
didn't last," Stewart says. the 1950's were tetraploids meaning was easy to tell cultivars apart," Asen
"What brought poinsettias to my that each plant had four sets ofgenes, said, "which made it easier for Bob
attention were the scientific meetings which made developing new varieties (Stewart) to track genetic differences."
that used to be held mostly between from conventional crossbreeding even Stewart also worked on genetically
Christmas and New Year's. The hotel more difficult. segregating such traits as branching
lobbies would be all dressed up with Bu—t he located a few t—hat were dip- stiff stems, deep coloration, and larger
poinsettias," Stewart explains. "But by loids two sets ofgenes that ap- bracts. These petal-like bracts are
peared to have longer keeping quality. really modified leaves that change
Agricultural Research/December 1992 5
—
— —
color; poinsettias' true flowers are tiny, of and the royalty due on a poinset- flowering or causing any other chang-
button-shaped structures in the center tia variety that was a very good keep- es," Cathey explains.
ofthe stems. er," Stewart remembers. "The conclu- "Height control was always a prob-
Once Stewart had improved plants sion ofthe court was that it must have lem in poinsettias for commercial
that met his standards, he needed to originated in our breeding program in growers. They used to bend the stems
find way—s to evaluate their keeping Beltsville because thejudge had seen around wires in an S-shape to make
quality not under the controlled our large body of work in this area and them look full enough. And from our
conditions of a greenhouse, but under he decided it had to be ours. In this standpoint, the plant was a worthwhile
the irregular treatment of home and case, he was wrong." research model because it was so diffi-
office care. But improved keeping quality has cult to grow," Cathey adds.
But how do you purposely handle not been ARS' sole poinsettia research The first compound that Cathey
plants the way they would be treated in accomplishment. found that worked to retard intemodal
shops and homes? lengthening was related to Amo 1618,
"Around Christmas each year, we PAUL ECKE a disinfectant chemical developed for
would take three or four poinsettias WWII and later reviewed for its bio-
around to each laboratory and office as logical activity. "I got Old Spice (Shulton
tests and then keep careful records of Company) to make some chemical vari-
how they lasted," Stewart says. "Our ations for me," he remembers.
problem became not one offinding Eventually, he found several com-
opportunities to evaluate plants, but of pounds that commercial growers
everyone wanting to get plants near could use to keep their poinsettias
Christmas time." from getting leggy. "All of them
One winter, to test his varieties' were replaced as time went along by
keeping quality under low light and more effective compounds." Cathey
low temperature, he had hundreds explains. "But at the time, this work
moved outside between the rows of had a major impact on helping poin-
greenhouses. "Ofcourse, that was the settias become a large industry."
year it didn't get below 50"F all win- From growth control. Cathe\ be-
ter," Stewart adds. came involved in scientifically quanti-
fying the conditions needed for poin-
How the Industry Grew settias to come into bloom exactly
when the mai'ket required.
Once he had poinsettias with good
To help the industiy he needed to
color and keeping quality, Stewart .
know not only how to cause them to
started making them available to any
flower, but also how to stop them from
grower who was interested in acquiring
flowering too soon.
the germplasm. Growers then contin-
Cathey found that exposing poinset-
ued the work, breeding their own spe-
tias to 3—seconds of light eveiy
cial varieties incorporating the qualities
In the I960's, horticulturist H. Marc minute or 3 minutes exeiy hour
of Stewart's poinsettias.
Cathey, then head of the Florist and from p.m. to a.m. each night held
"I got rid of a lot ofthe genetic gar- 1 1 1
Nursery Crops lab, began using poin- the plants on the brink of flowering un-
bage that was in the old poinsettias,"
Stewart says. "And my work Hterally settias as a model in his investigations til the grower was ready lo ship.
into the fundamental chemical control He also helped de\elop other direc-
forced the whole industry in the direc- —
of plant growth. His work later tions for growing poinsettias from
tion of diploids and good keepers."
branched out into the effects of light, the quality and intensil\ of light, to the
Although no commercial variety
temperature, and other stresses on tenipcralures needed for blooming.
grown today is directly Stewart's, there
poinsettias. In the l%()"s and 1970's. Cathey
was a time when even the U.S. judicial
system recognized his contributions. "What I found was a chemical treat- ran a national testing program w iih the
ment that would reduce intemodal cooperation of growers to ex aluate
"Two growers, one think was from —
I length the distance a stem lengthens growing conditions and new \arieties.
overseas, had sued over the ownership —
between leaf nodes without delaying It continued until the "basic conditions
6 Agricultural Research/December 1992
—
Poinsettia
varieties are
extremely
sensitive to
for commercial production were com- cause damage to the affect the plants" abilit\' to
pletely set down." ozone la\"er in the up- air pollut- deal with air pollution.
It would be hard to point to ARS" per atmosphere."" ants; even a Kiizek and Semeniuk
specific contributions to each poinset- Krizek explains. little sulfur disco\'ered that the fewer
tia \aiiet}" because so much progress He and retired horti- dioxide can stomates a plant has. or the
has been made since the original re- culmrist Pete Semeni- smaller the stomate open-
injure them.
search, but "the industr}' certainly uk found one of the mgs. the more it can resist
learned a lot from what we did in groups of pigments damage from pollutants.
USDA." Cathe\- said. ".\nd they that Sam Asen had Wliile Krizek"s interest
wouldn't othen\ise ha\"e had access to identified from poin- has recent!}' been in de\"el-
the t}pe ofpioneering laborator} work settias—and other oping a scientific under-
we did in basic plant biology." plants —the fla- standing ofhow all plants
vonoids w as \qt\ differ in theii" tolerance to air
What About the Future? important m protecting pollution, his w ork has also
plants from the harm- benefited poinsettia growers.
Today, plant ph} siologist Donald
T. Krizek. with ARS Climate Stress ful effects of ultra\'io- "I often get calls from
" let radiation. gi'owers who ha\"e had a
Laborator}'. uses poinsettias as one of
These pigments, whole greenhouse ofpoin-
his model plants as he in\estigates the
which occur within the settiasjust die on them and
effects of drought and atmospheric
surface ofthe leaf, sene as optical screens they want to know wh}'."" Kiizek
changes such as air pollution and ultra-
protecting the internal tissues from dam- sa}'s. "What I found was that most
\iolet radiation.
age b\" LA' radiation."" Krizek explains. greenhouses use kerosene-powered
"In the 1970"s. w e became inter-
Poinsettias ha\'e also ser\'ed as a heaters. Sometimes the kerosene is
ested in the effects of ultraviolet ra-
con\'enient model for finding out how not as pure as it should be, and sulfur
diation, largely because of the U.S. —
the number and size ofstomates spores dioxide is produced.""
Department of Transportation's con-
through which plants exchange gases Since man}- poinsettia \'aiiedes are
cern that supersonic airplanes might
extremel}- sensiti\ e to air pollutants,
even a little sulfur dioxide can injure
them. M}'ster}- soh'edl
PAUL ECKE
Kiizek and Semeniuk also found an-
other factor that ma}' be useful to grow-
ers. Exposing poinsettias to mild stress
earl}" in their gi-owth can protect them
from much greater stress later.
"Fi\'e da}"s at cool temperaaires.
68T. when the bracts are de\'eloping
can protect the plants against later
damage from sulfur dioxide or other air
—
pollutants."" Krizek sa} S. B}- J. Kim
Kaplan. ARS.
H. Marc Carhey is The Xatioual
Chainnaufor Florisr and Xiirseiy
Crops ReyieM'. USDA-ARS Xarional
Program Staff. 10300 Bahiinore Ave..
MD
Behsville. 20705-2350. Phone
(301 1 504-6233fax number (3011 504-
6191. Donald T. Krizek is at the
USDA-ARS Climate Stress Laboratoiy.
Bldg. 001. 10300 Baltimore Ave.. Behs-
MD
ville. 20705-2350. Phone (301) 504-
5324 faxnumber (3011504-6626
Agricultural Research/December 1992 7
—
Switchgrass in a laboratory test channel gives agricultural engineer Don Meyer (left) and agronomist Seth Dabney
a chance to measure its sediment-trapping capability in a controlled environment. (K4836-5)
Stiffgrasses could be a low- alists. They were saying that bulldozer- about the grass. Until the mid- 1940's,
tech solution to a widespread built teiTaces like those we use in the vetiver was grown in the southern
problem. United States disturb topsoil and take states and was prized for its \ aluable
—
Just as grasses planted along beach- water away too quickly rather than roots containing an LU'omatic oil used
es protect sand dunes from wind and letting it soak in. And that vetiver grass for making long-lasting perfumes.
water erosion, stiffgrasses could help hedges do a betterjob ofcontrolling After chemists found out how to synthe-
—
U.S. farmers solve a major problem erosion a—nd conserving water at much size perfume, commercial production
protecting valuable topsoil. less cost than terraces fomied by ofthe grass practically ceased.
In India in 1988, two World Bank earthmoving equipment." Seeds of veti\er collected in that era
agriculturalists extolled the virtues of With the aid of literature and slides, were found by ARS agronomist Gilbert
using live hedges of vetiver grass these vetiver enthusiasts provided Lovell at the Regional Plant Introduc-
(Vetiveria zizanioides) for controlling strong evidence that the grass was tion Station, Griffin, Georgia. Some of
water erosion and argued their merits fulfilling these claims in India, the West those seeds were still viable after
over U.S. bulldozer-built terraces. Indies, and Fiji. almost 40 years in storage.
Doral Kemper, national program lead- "Slim, green rows ofvetiver grass Next. Kemper and SCS national
er for soil management, was there with planted by farmers across hillsides 10 plant materials specialist Curtis Sharp
other ARS experts as an adviser on soil to 30 years ago grew into thick, sturdy called together interested ARS. SCS,
management technology for the U.S. grass hedges 9 feet tall and 6 to 7 feet and uiii\ ersit\ perst)nncl to ctmrdinate
Agency ibr International Development. wide. They slowed runoff significantly reseai'cli and development acti\ ities on
"It was a somewhat humbling and deposited sediment," Kemper says. grass hedges for contriMiing erosion.
experience," Kemper recalls. "As "Over the years, these deposits have The group soon learned that using
representatives of the country that has formed wide, productive bench terraces grass hedges is not a new idea here
mounted the most extensive erosion uphill from the hedges." either. About 40 years ago, SCS
control effort on planet Eaith, we were Stateside, Kemper, working with proposed using hedges for developing
less than wholly receptive to the cooperators at USDA's Soil Conserva- natural teiTaces on steep lands.
message ofthe World Bank agricultur- tion Service (SCS), Ibund (uil more
8 Agricultural Research/December 1992
SCOTT BAUER
"We're not sure why the idea didn't In 1991. silvergrass hedges were "Soil accumulated as far as 10 feet
catch on;" Kemper says. "We suspect tested on erosion plots near Oxford. uphill from the grass hedges inJust a
that farmers were in a huny to get their Mississippi. About a month before year." he says. "It was fertile soil that
terraces built and earthmo\"ing equip- cotton planting, clumps of 1-foot-tall would ha\-e been lost ifit had been on
ment became readil\' a\ ailable to do grass from Mateme were planted about unprotected cottonfields."
thejob. Since the go\emment subsi- 7 inches apait and uphill from the "How hedges work to protect fields
dized the construction ofterraces, lower ends of 72-foot-long plots with is simple," explains McGregor. "As
farmers adopted the quick alternative." 5-percent slopes. gaps between the hedges fill in. more
The sroup besan testing different "Just one row ofthe grass held back water ponds up uphill from the hedges,
types of\eti\er grass at a dozen U.S. nearh' half ofthe soil lost or eroded more sediment is deposited in these
locations to fmd out whether it would from plots \\"ithout hedges." sa}"s Keith ponds, and less soil and water ai-e lost
hve up to World Bank expectations. McGregor. ARS agriculmral engineer from the field."
USDA
"All the vetiver types grew well at the National Sedimentation He sa\"s that plans are to continue
over the summer. But winter freezes Laboratory in Oxford. the smdy for at least 2 more years.
killed most stands." Kemper says, Another candidate the gi"0up found
"except for se\'eral hedges planted by SCOTT BAUER was switchgrass iPaniciim virgatum
SCS plant materials speciahst Mike L.). which showed promise for control-
Mateme across shallow guUies at Fort ling both wind and water erosion.
Polk, Louisiana, where U.S. Army .\RS agronomist Seth Dabne\". the
tank maneuvers had denuded extensi^•e Oxford project's grass expert, is testing
areas. There, the 100-foot-long vetiver several types of sil\ergrass and
hedges not onl}' flourished, but caught s\^'itchgrass as hedges. Last summer,
sediment 18 inches deep on the he planted ten 3-foot-wide strips of
upslope side injust a }'ear." switchgi'ass seed across the slopes of a
20-acre soybean field.
Evaluating Other Grasses "We \^"anted to see under field-scale
Mateme's findings were so encour- conditions how well the stiff-grass
strips held back concentrated mnoff
aging that the group began a search for
water that would flatten most grasses."
other grasses with stiff stems that
wouldn't bend over when water ponds Dabney sa} S.
"We've estabhshed a stand, but
up against them and that are adapted to
switchgrass gi'ows slowh' for the fu'st
the climates of \ arious U.S. regions.
Kemper found one candidate grass Technician Tommy Winter measures year or so. The young hedges are not
growing outside his office at the the height ofa grass hedge at the lower yet stiffenough to stand up against the
Beltsville Agriculmral Research end ofa cotton plot while agronomist concentrated mnoff near the bottom of
Center, Mar\iand. He had been Alan Hudspeth records the data. the field." Dabne\' is working with
(K4838-19)
local farmers to de\'elop practical
watching an ornamental sil\'ergrass,
methods to estabhsh and manage
(Miscanthus sinensis Andersson). grow
hedges to best control erosion.
thick, closely packed stems and survive
From Ma\' through September, Using grass hedges will also help to
several cold winters.
about 14 tons an acre of soil were lost maintain water qualit}' downsti-eam.
Also thriving in nearby plantings
on grass-hedged plots that were con- "An}' conser\"ation practice that lea\'es
were se\'eral closeh' related silver-
grasses planted in 1980 by .ARS" Jack \'entionall}' tilled compared to 24 lost more ofthe soil in place on tlie land
on plots without hedges. On untilled also improves the water quaht} of our
Murray and Ke\in Morris, ofthe
plots, these losses were 0.7 tons with streams and lakes." McGregor says.
National Turf Grass Association. They
hedges versus 1.3 \^•ithout. Dabney adds. "Hedges planted on
provided vegetative silvergrass to
Mateme, who multiphed it in Louisi- McGregor says. "A 5-percent slope the contour give farmers a guide to
is enough for mnoffto cause serious farni along. .And b\' temporarih' pond-
ana plots during the winter months and
made it a\'ailable to all who needed it erosion during rainstorms. Longer ing mnoft'. hedges ma}" be able to hold
the following spring. slopes in fields would cause even more sediment on fields \\here crop residues
soil to erode." must be tumed under to prevent build-
Agricultural Research/December 1992 9
—
up of insects and diseases or to con- hedges than plant height is an increase tected areas where loose soil particles
trol weeds where herbicide appUca- in the size and number oftillers stay settled. Otherwise, unsettled parti-
tions are a problem." sprouts from the base ofthe stem. cles become projectiles that blast addi-
Past research under the direction of Tillers help fill in the gaps between tional particles loose to become airbome."
Oxford ARS agricultural engineer Don plants and slow the flow. Large tillers He says that in the northern plains,
Meyer with finer stemmed grasses like give hedges stiffness so they don't hedges also trap snow. Some water-
tall fescue, Festuca arundinacea, and bend over in deep flows." borne sediment from their rare runoff
bermudagrass, Cynodon dactylon, Meyer and Dabney are building a events is deposited in the draws, caus-
showed their ability to trap sediment new test channel where they will study ing terraces to form across the hedges.
from shallow flows. However, they different types ofhedges to see how • Near Big Springs, Texas, where
were flattened by deeper flows. crop residues and sediment in runoff only about 17 inches of rain fall a year,
"A major challenge now," says affect the amount ofwater ponded and ARS agronomist James D. Bilbro is
Meyer, "is to find grasses that will the length oftime it remains. finding that hedges of Alamo switch-
stand up to deeper concentrated flows Kemper says that grass hedges are also grass grow over 6 feet tall and have
coming offlarge, sloping fields." being studied at several other ARS labs. dense tillers and deep rooting.
Former ARS research associate. • Based on 25 years ofresearch by "Growing cotton on these sandy
Gale Dunn, who worked with Dabney, ARS soil scientists Al Black and J. soils makes them extremely vulnerable
evaluated the ability ofgrass hedges to Kristian Aase at the ARS Northern to wind erosion," says Bilbro. "In this
slow runoff water in a test channel at Plains Soil and Water Research Center, semiarid area where crop residues ai'e
the Oxford lab. Sidney, Montana, Kemper is con- generally in short supply and the poten-
"We found that all the 2-year-old vinced that grass hedges will also help tial for wind erosion is quite high,
vetiver, silvergrass, and switchgrass control wind erosion. switchgrass hedges can certainly re-
types we tested were strong enough to Aase says that "Hedges of tall duce soil loss from wind erosion."
pond flowing water up to 1 foot deep," wheatgrass, Elytrigia elongata, seeded • Also adding to our knowledge of
Dabney says. "While all these grasses at 50-foot intervals, reduce wind veloc- how to use grass hedges effectively to
grow tall and erect, more important for ity at the soil surface and provide pro- control erosion are studies by ARS ag-
Lmy
ricultural engineer Kramer at
Deep Loess Reseai'ch Station neai"
Traynor, Iowa, and soil scientist E. Eu-
gene Alberts on claypan soil erosion
study plots near Columbia. Missouri.
Ki-amer has established a switch-
grass hedge on a 15-acre com field of
highly erodible soil with slopes of up to
16 percent. He's using sihergrass
plantings to reinforce the hedge w here
it must stand up to concentrated rtinoff.
"Perennial grass hedges don'l grow
quickly, so time is needed \o gi\c thcni
the opportunity to show w hal ihc) can
do." Kemper said. "This lime w c"rc
not going to lei our inipalicncc keep us
from completely e\ alualing ihis tech-
—
nology!" By Hank Becker, ARS.
To conicicl ac/(7///'n/.s nwmioiii'c/ in
this iirliclc, write or coll Honk Bec ker.
USDA-ARS
Inforniotion Stoff. Bldg.
419, BARC-Eost. Bcltsvillc. Ml)
20705-2350. Phone (JO/) 504-8547,
fox niunlwriJOl 504-8030.
)
10 ALiriculiuial Research/December 1992