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History of hybrid corn

History of hybrid corn



I developed this presentation for my Intro to Sustainable Agriculture class in fall 2012.

I developed this presentation for my Intro to Sustainable Agriculture class in fall 2012.



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    History of hybrid corn History of hybrid corn Presentation Transcript

    • Learning fromthe history ofhybrid cornhttp://blog.nebraskahistory.org/?p=6713
    • What do you know about the history ofhybrid corn and its role in theindustrialization of agriculture???
    • At the beginning the1930s, almost no hybridcorn was planted in theCorn Belt. By 1940,hybrids accounted formore than 70% of thecorn planted in thecentral Corn Belt andthousands of farm kidshad a new summer job– detasseling corn forhybrid seed companies.
    • Geneticists, historians, sociologists,and economists have all written abouthybrid corn as a prime example oftechnology transfer –from basic research(science motivated by the quest for knowledge)to transformation of industry.Why was the development ofhybrid corn so transformative??
    • GH Shull (1874 – 1954)Considered the father of hybridcorn, GH Shull began studyinginheritance in corn in 1905. Hedocumented the reduction of vigorresulting from inbreeding and thesubsequent improvement of vigorfrom crossing in-bred lines. Theseexperiments provided the scientificbasis for hybrid corn. Schull alsofounded the journal Genetics(which is considered to this dayone of the top internationalscience journals), and served as aProfessor of Botany and Geneticsat Princeton University.
    • Others have described hybrid corn as one of thegreatest marketing success stories of all time.
    • In 1950,>100 companiessold hybrid seedcorn in IA
    • Prior to hybrid corn, farmers mostlyplanted seed that they saved fromthe previous year. In the late 19thcentury, the USDA began sponsoringCorn Shows across the Corn Belt toencourage farmers to carefullyselect the best looking ears (biggest,straightest rows, brightest color) touse as their seed stock.Was this a good strategy?
    • Population improvementi.e., increasing the frequency of desirable traitsthrough mass selectionis a basic principle of crop breedingSo why didn’t theCorn Showscontribute to highercorn yields?
    • highest total kernel ct per acre (not per plant or per ear) -> highest yield
    • The seeds from the biggest and best looking ears in a field areactually less likely to have good genetics for high yields!
    • Cornshows
    • What is the main cause of departurefrom trend line yields?WEATHER!
    • Why did corn yield begin increasingdramatically in the 1930s?(1) The introduction of planned breeding programs.The confusion of breeding, in general, withhybridization as a particular method is common.(1) The introduction of more efficient experimental andstatistical test procedures.(2) An unprecedented effort by government agenciesto develop improved inbred lines in support of thehybrid-seed strategy.(3) Changes in cultivation techniques, such asmechanization and increased use of fertilizers.
    • Comparison of corn and wheat yields bringsinto question the claim of a special yieldincrease due to hybridization. During theperiod 1937-1945, when the acreage sownto hybrids increased rapidly in the CornBelt, wheat yields increased at 4.4 percentper year, while corn yields increased only2.8 percent per year.
    • Do these look similar to the corn yield curve?
    • Does this curve look familiar?
    • Do you know howhybrid corn seedis produced?
    • Inbred lines are identified that produce hybridswith desirable traits when crossed
    • The designated femaleplants get detasseledThe designated male plants shedpollen that is received by silks onthe designated female plants.The designated male plants get removed after pollination
    • So where do inbred lines come from?
    • Just before pollen shedbegins, a bag is placed overthe tassel to catch the pollen.The next day the tassel bag iscarefully removed and placedover an ear (on the sameplant) that had been enclosedin another bag to preventpollination. The tassel bag isshaken so that pollen grainsfall on receptive silks and self-fertilization occurs.Creating inbred lines
    • Historically 7+ generations ofself-pollination were neededto create new inbred lines.Inbreeding depression
    • The DoubledHaploid Facilityat ISU will allowdevelopment ofpure, inbredlines in only twogenerations,taking about oneyear.http://www.sciencedaily.com/releases/2010/04/100405175134.htm
    • Double cross hybridization was the bigbreak-through that launched the hybridseed corn industryDo we use double crosses today?
    • Hybrid vigor is greatest in single-cross hybrids!
    • HYBRIDIZATION transformed cornseed into a COMMODITY.WHY?Seed corn companies recognized that oncefarmers decided to plant hybrid corn theywere committing to purchasing seed from acommercial seed producer every year.
    • As farmers quickly adopted hybrid corn,the production of hybrid seed became ahighly profitable industry.At the same time, USDA funding waschanneled into public research onhybridization & all other methods of cornbreeding were effectively abandoned.The combination of commercial interest andsubstantial government support quickly ledto a new type of public-private partnership.
    • In 1926, Henry A. Wallace,the editor of Wallaces’ Farmer(and future Secretary of Agricultureand U.S. Vice President), foundedthe "Hi-Bred Corn Company“ inpartnership with a group ofbusinessmen in Des Moines, IA.Wallace had been experimentingwith hybridization of corn and wasconvinced that hybrid seed cornwould transform agriculture.The Hi-Bred Corn Companywas renamed Pioneer Hi-BredCorn Company in 1935.
    • Henry A Wallace was perhaps themost influential of all USSecretaries of Agriculture (1932-1940). He oversaw theestablishment of the first farmprograms which helped tostabilize farm prices and conservesoil during the Great Depressionas well as serving as thefoundation for all subsequentfarm programs. The RuralElectrification Administration,food stamps, the school lunchprogram, and Food for Peacewere also begun under Wallace.
    • “In 1934 alone, Secretary of AgricultureWallace traveled more than 40,000 miles bycar, train, boat, and plane. He made publicappearances in all 48 states, delivered 88speeches, wrote 20 articles for magazines andjournals, published two books and a lengthypamphlet, received two honorary degrees, andmet with reporters by the score."American Dreamer: A Life of Henry A. Wallace
    • 4 generations of Henry Wallaces profoundly influenced American Agriculture
    • Henry A Wallace and Hybrid HypeIt is important to consider why so many farmers werewilling to purchase hybrid corn seed even beforehybrids offered them a clear economic advantage.(1) Pioneer Hi-Bred and other seed companieslaunched very aggressive marketing campaignsdirected at potential adopters, and(2) Henry A. Wallace, co-founder of Pioneer Hi-Bred,former editor of Wallace’s Agriculture and US Secretaryof Agriculture (1932-1940) put the full weight of theUSDA behind the advancement of hybrid corn.2 important factors
    • By today’s standards, the glaring conflict of interestbetween Henry A Wallace’s financial interest in thePioneer Hi-Bred Company and his use of thegovernment agency he controlled to advertise andadvocate for hybrid corn would be consideredoutrageous.All the promotion by the USDA and privateindustry might not have been able to overcomefarmer reservations about hybrids without twoother factors.Conflict of interest????????
    • Tipping pointThe key factor which convinced large #s offarmers of the value of hybrids was extremeweather - catastrophic droughts across theCorn Belt in 1934 and 1936.The superior drought tolerance of a fewspecific hybrids relative to open pollinatedcorn in 1934 and 1936 was a tipping point formany farmers.
    • The relative advantage of early hybrids over open-pollinated corn was greatest when environmentalconditions were unfavorable for corn yield
    • The relative yield advantage of hybrids overinbred parents has actually decreased over time.Experiments clearly demonstrate that yield gainsin hybrid corn are primarily due toimprovements in abiotic and biotic stresstolerance (healthier plants that tolerate higherpopulations) and that these improvements haveoccurred in both inbred parents and hybridprogeny.
    • http://www.agry.purdue.edu/ext/corn/news/timeless/images/PltPop-Indiana.gifAverage harvest population for corn in IN1986-2012
    • Is a commercialcorn breederlikely to searchfor genetics thatperform well atlow populations?Recent population studies in IAhttp://www.extension.iastate.edu/NR/rdonlyres/8D20C318-7854-4BE4-A1A1-A6C767D36734/100322/rsz0423PltPopgraphics1.jpg
    • Have you ever counted the pods on a soybean plant?What happens when moderncorn hybrids are planted at lowpopulations?
    • “I include three of the top OPVs for Iowa (from the1920s and 1930s) in my trials and find that althoughthey differ from each other in yielding ability, all threeof them are on the bottom for yield and also for stressresistance at modern planting rates, but are equal inyield to hybrids at the super-low rate (1 plant/squaremeter)”.Don Duvick
    • Breeders have dramaticallyimproved corn yield potential forthe conditions under which theywere testing…Don Duvick
    • 41 years with Pioneer!Central participant in most of modern corn breeding
    • (1) Precise genotype identification and multiplication. Instead of a randomcollection of hybrid and/or inbred plants in an OPV, the most superiorhybrid combinations can be identified and reproduced in unlimitedquantity.(2) Breeders of hybrid crops can react faster and with more options tomeet changing times and changing demands, as compared to breeders ofeither inbred crops or OPVs. New hybrids with needed new traits can bemade and put out to test within one or two seasons, given a broad-basedpool of inbred lines.(3) Hybrids facilitate combination of multiple traits into one cultivar, e.g.,one hybrid can carry several dominant genes for disease resistance, somecoming from one parent, some from the other, or one hybrid may deriveits drought tolerance from one parent and its lodging resistance from theother parent.Hybridization is a process that fits very wellwith the industrialization of agriculture
    • In the early 1960s, seed corncompanies began to use male sterilecytoplasm to eliminate the need forhand detassling.Texas male sterile cytoplasm (Tcms)was rapidly bred into ~ 90% of allhybrids!
    • The disease, which first appeared in the UnitedStates in 1968, reached epidemic status in 1970 anddestroyed about 15% of the corn crop.Southern Corn Leaf Blight Epidemic (1970)It is estimated that Illinois suffered aloss of 250 million bushels!
    • “At current market prices of about $1.50 per bushel,losses amount to approximately 1 billion dollars,attributable primarily to a new race of fungus that ishighly virulent on corn with T-type cytoplasm, which isextensively used in hybrid seed production”
    • Amazingly SCLB disappeared just as fast as itswept across the Corn Belt. Contributingfactors include the aggressive burial of infectedresidues in fall 1970, early planting and lessconducive weather in 1971, and a rapid returnto normal cytoplasm genetics.The hybrid system allowed corn seedproduction to turn on a dime and return toparent lines that did not include T-cytoplasm.Mechanical detasseling continues to this day.
    • “Every ag economist knows the story of hybrid corn.Z. Griliches an economist at IA State used theadoption of hybrid corn in the United States as themain example for his model oftechnological diffusion.This classic article is taught in every graduateprogram and is a major reason why the adoption ofhybrid corn is so widely viewed as the perfectillustration of how farmers respond to theavailability of superior technology.”As discussed, the real story is more complex.
    • Technological ReinforcementAs hybrid seed corn became a profitableindustry, R&D by industry and public scientistsrapidly increased corn yield potential creating aself-reinforcing momentum away from openpollinated breeding efforts. The profitability ofhybrid corn attracted private capital that helpedto advance seed production and distributiontechnologies/infrastructure. Lastly, theuniformity of hybrid corn made it a good fitwith early mechanical harvesting equipment.
    • What is a technology treadmill?
    • What is “technology lock-in”?
    • Most farmers are using methods which do notallow production flexibility. American agricultureof the conventional type "works" only when thethrottle governing energy and input flows ispulled all the way out. Farmers lack the option ofswitching-either permanently or temporarily-toan alternate system that performs well whenconventional production is not profitable.Paraphrased Robert Rodale quote that caught my attention back in the 80s