1. © T. M. Whitmore TODAY Maya Corn God READINGS: Plants and Society (reserve) pp 197- 203; 259-260 Omnivore’s Dilemma: 15-64; 85-99 Readings for Next week: Nature’s Metropolis pp 205-259 On line in Contemporary issues… folder: “Power Steer” (M. Pollan) Amber Waves article on Hispanic workers Omnivore’s Dilemma 65084, 185-238 Hungry Planet pp 22-29 (Australia outback); 162-165; 266-275 (USA)

2. © T. M. Whitmore Questions re Last Time “The Green Revolution”

3. © T. M. Whitmore Problems & Successes continued Impacts on large and small holders  Difficult for poor to afford the “package”  Benefits of improved output mostly to the already relatively better off Other criticisms  Genetic loss  Petroleum dependence (fertilizer)  Dependence on irrigation  Does not “solve” the food problemfood

5. © T. M. Whitmore Maize Maize is a grain bearing grass family plant (like all other grains) – but unlike any other Through selection humans have created a plant that no longer has the ability to disperse seeds and produce offspring without human intervention

6. © T. M. Whitmore Controversy in origin of maize The Maya considered corn a gift from the gods and cultivating it was a sacred duty Botanists, however argue: Battle of Titans:  Mangledorf and Beadle Mangledorf and Beadle  1930s through 1970s

7. © T. M. Whitmore Paul Mangledorf: Tripsacum school He argued that:  Domesticated maize was the result of a hybridization event between an unknown wild maize from S America and a species of gamma grass, Tripsacum. Tripsacum  Teosinte (a wild grass found in C. Mexico) was of hybrid origin, the offspring of a cross between another genus of grasses (Tripsacum) and maize. Teosinte

8. Paul Mangelsdorf George Beadle

9. Robert Soreng @ USDA- NRCS PLANTS Database Tripsacum latifolium L. (gamagrass)

10. Immature ears of Zea diploperennis (a variety of teosinte) whole and sectioned with a few mature fruitcases, one of which is cracked open to expose the grain (photo by Hugh Iltis)

11. © T. M. Whitmore Teosinte The accepted wisdom up to the 1970s was that the morphological differences between teosinte and maize were simply too great for maize to have been selected from teosinte by ancient peoples over a few thousand years. Thus teosinte was placed in the genus Euchlaena in the 19th century rather than in Zea with maize (Z. mays)

12. © T. M. Whitmore George Beadle: Teosinte school He argued that  Some teosintes were of the same species as maize, while others belonged to a distinct species  A Mexican annual teosinte (Zea mays ssp. parviglumis) was the direct ancestor of maize.  A small number of major mutations could have converted this teosinte into a useful food plant during the early stages of domestication.

13. © T. M. Whitmore Battle Decided Maize is a direct domesticate of a teosinte (Zea mays ssp. parviglumis), native to the Balsas River Valley area of southern Mexicoteosinte With up to 12% of its genetic material obtained from another teosinte species Zea mays ssp. mexicana through introgression.Zea mays ssp. mexicanaintrogression

14. © T. M. Whitmore Teosinte II The teosintes make up a group of large grasses of the genus Zea found in Mexico, Guatemala and Nicaragua. Virtually all populations of teosinte are either threatened or endangered Much scientific interest in conferring beneficial teosinte traits, such as insect resistance, perennialism and flood tolerance, to cultivated maize lines, although this is very difficult due to linked deleterious teosinte traits. Much scientific interest

15. Teosinte and "reconstructed" primitive maize. (photo by John Doebley) Photos courtesy of the Doebley Lab, Department of Genetics University of Wisconsin-Madison Ears of Zea mays ssp. parviglumis (maize’s teosinte ancester) and maize (photo by Hugh Iltis)

16. Zea mays ssp. mexicana (teosinte) plant (photo by Hugh Iltis)

17. Wild form of Zea mays ssp. mexicana plants growing in a field in Michoacan, Mexico (photo by John Doebley)

18. Geneflow from teosinte (maize wild relative) to maize. Jarvis, Devra I. and Toby Hodgkin

19. Teosinte ear (Zea mays ssp mexicana) on the left, maize ear on the right, and ear of their F1 hybrid in the center (photo by John Doebley)

20. © T. M. Whitmore Maize Domestication Maize development is thought to have started from 7,500 to 12,000 years ago Archaeological remains of the earliest maize cob, found at Guila Naquitz Cave in the Oaxaca Valley of Mexico, date back roughly 6,250 years > 200 varieties in the Americas by 1492 (amazing breeding achievement).

21. © T. M. Whitmore Maize genetics A distinguishing feature of this grass is the separation of the sexes among its flowering structures. Unlike other grasses, which produce perfect (bisexual) flowers, maize produces male inflorescences (tassels) which crown the plant at the stem apex, and female inflorescences (ears) which are borne at the apex of condensed lateral branchestassels

22. The International Institute of Tropical Agriculture (IITA)

23. © T. M. Whitmore Maize genetics II Maize is open pollinated (wind blows copious pollen from stamen to ovaries) most other grains are not Fields of wheat or rice will be more or less homogeneous generation after generation – (when planting saved seed); not so for maize since it can cross breed so easily with other varieties that may be growing nearby  This may be a plus since the new accidental crosses may have better yield or other beneficial traits  But also a negative since the new cross may be worse

24. © T. M. Whitmore Maize genetics III The high productivity of maize is due to its large leaf area and to its C4 photosynthetic pathway C4 trait (shared by other tropical species adapted to survive periods of drought stress)  Is a more efficient means of exchange of water vapor for atmospheric CO 2 C4 species can produce more dry matter per unit of water transpired than can plants endowed with the conventional (C3) photosynthetic pathway.

25. © T. M. Whitmore Maize genetics IV Maize’s cross-pollinating has contributed to its broad morphological variability and geographic adaptability Varieties may range from 0.5 - 5 m height Mature in 60 to 330 days Produce 1 to 4 ears per plant (depends on density planted) 10 to 1,800 kernels per ear (each of which could make a new plant)

26. © T. M. Whitmore Maize genetics V Yield from 0.5 to 23.5 tons of grain per hectare Kernels may be colorless (white) or yellow, red, blue or variegated with these colors in mottled or striated patterns. Produced from 50° latitude N to 40° S, is adapted to desert and high rainfall environments, and to elevations ranging from 0 to 4,000 meters above sea level.

27. © T. M. Whitmore Maize genetics VI There is high genetic biodiversity in the Mexican maize pool, a factor of great importance for the breeding of current and future maize cultivars Mexican maize  at least 42 landraces in 3 groups

28. A sample of the diversity represented in the corn crib of one farmer in the highlands of central Mexico. (photo by Hugh Iltis)

29. © T. M. Whitmore Major maize phenotypes (groups of varieties) Dent corn  Most produced type globally = 73% of commercial production,  Yellow dent = “field corn”  Used as livestock feed and for industrial manufactures (starch, corn sweetening, oil, alcohol)  Some white dents are used for human foods in USA, e.g., breakfast cereals, and grits  Produces higher yields and dominates production in North America

30. © T. M. Whitmore Major maize phenotypes II Flour corn (usually white)  The preferred form for direct human consumption  Soft starch that is easily ground to produce meal that can be consumed directly, or as a flat bread, dumpling or beverage  Currently accounts for 12% of commercial production Popcorn - the original domesticated type Flint corn –produced in areas where cold tolerance is required (e.g., Italy for polenta) and is often preferred for hand grinding Flint corn Sweet corn – AKA corn on the cob Sweet corn

31. Minnesota State University, Mankato White flint on left, modern hybrid dent in middle, and Yellow Northern Flint

33. © T. M. Whitmore Hybrid corn: World’s 1st Biotechnology Windborne pollen effects fertilization of open-pollinated varieties: there is no control of the male parentage Thus the drive to develop inbred lines. These are developed by a combination of inbreeding and selection.  Inbreeding to transfer of pollen from an individual plant to the silks of the same plant.  This process is repeated for several generations until the strain becomes stable, or true breeding.

34. © T. M. Whitmore Hybrid corn II A geneticist, G.H. Shull, in 1906  Noted the reduction in “hybrid vigor” (heterosis) in inbred varieties and  Restoration of vigor upon cross breeding inbred varieties Cross-breeding involves the cross breeding of selected parents  “Single crosses” are produced by crossing two inbred lines.  “Double crosses” are produced by crossing two different single crosses.  Selection is practiced in each generation to maintain only the superior types.

35. © T. M. Whitmore Hybrid corn III Aim of modern hybrids is to produce a plant with reliable characteristics (e,g., yield) and modify the local ecology to fit  This is opposite from traditional breeding that aimed to breed a local variety to fit well with local environmental conditions

36. © T. M. Whitmore The shift to hybrids By 1930s seeds of "double cross" hybrids could be produced at a price US farmers could afford. Farmers could take advantage of the benefits of hybrid corn varieties that resulted in an increase in vigor, yield, and uniformity But until the 1940s most farmers still were growing open-pollinated (OP) varieties But by 1956, all of the Corn Belt and 90 per cent of the U.S. corn land was in hybrids.

37. © T. M. Whitmore The shift to hybrids II The shift from OPs to hybrids occurred because hybrids were  higher yielding (more corn on fewer acres) higher yieldingmore cornfewer acres  Stood up better (i.e., resisted lodging)  Were more tolerant to stresses (drought, diseases, insects)  Had greater uniformity – they were better suited for mechanical corn picking  The grain quality was better But, saved seeds from these hybrids do not necessarily breed true in farmers’ fields

41. © T. M. Whitmore The shift to hybrids III The introduction of hybrids also allowed, for the first time, a cost effective protection of intellectual property in corn breeding intellectual property  First public institutions (ag schools such as NCSU) but later private firms did the costly work to produce these hybrid seeds Farmers buying the seed could not maintain or recreate the hybrid themselves and thus needed to buy seed each year if they wanted to maintain the yield advantage the corn hybrids provided.

42. © T. M. Whitmore Consequences of the shift to hybrids Hybrid corn was and is a huge scientific and commercial success. There were, however, unforeseen consequences of this technology.  Existing (and genetically diverse) open- pollinated varieties throughout the Corn Belt quickly disappeared and consequently uniformity in the cornfields greatly increased.  This increased the potential for genetic vulnerability e.g., Southern Corn Leaf Blight, a fungal disease, in 1970

43. © T. M. Whitmore The shift to hybrids II Unforeseen consequences of this technology…  Farmers were “tied” to the seed companies – costs went up but production went up faster!seed companies Current opposition to genetic engineering (the new hybrid technology)  Potential risks of introducing genetically engineered varieties to the environment  Greed of companies, etc There was a lot less opposition and little if any discussion about the potential risks for traditional hybrids

45. © T. M. Whitmore New Maize hybrids Newest push is for open pollinated maize varieties with commercial hybrid-like good qualities Apomixis (recent patents of a kind of cloning): to produce corn, wheat, and other cereal grains able to reproduce by themselves (saved seed) without losing hybrid vigor, desirable agronomic traits, or useful disease- or insect- resistance.

46. © T. M. Whitmore Maize Ecology Grows in more eco-zones than any other major crop Needs sufficient water especially during a 1- month period of tasseling  If too dry => significantly lower yields  Also need rain in later period when grain is filling  Thus drought is a problem: not total annual rain but need sufficient in these key growth periods Traditional farmers plant multiple varieties with different maturities (with different dates of tasseling) so if rains are inconsistent they get better yields – less risk than monocrop

47. © T. M. Whitmore Maize Production Produces more food per hectare and per labor than any other grain  2x the yield of wheat; 7 m calories/ha (~ rice); wheat 4m calories/ha;  more efficient than most grains in converting sunlight due to C4 pathway  much of the plant can be used: eg stalks for fuel and fodder A greater weight of maize is produced each year than any other grain

48. © T. M. Whitmore Maize Production II In 2000, all maize in world = 140 m ha; 96 m in 3rd world (thus 2/3 of all maize land is in developing world)  But only 46% of total production is in 3 rd world since hybrid (yellow field) maize in 1st world is more productive Worldwide production was over 600 million metric tons in 2003  World average yield = 4,255 kg per hectare  Average yield in the USA was 8,600 kg per hectare  sub-Saharan Africa average yield = 1,316 kg per hectare

49. © T. M. Whitmore Maize Production IV World maize production  USA 43%  China 18%  European Union 7%  Brazil 6%  Mexico 3% (only!) Maize consumption (by people directly)consumption  Note Sub-Saharan Africa!

50. © T. M. Whitmore US Maize Uses The “Corn Belt”Corn Belt In North America, fields are often planted in a two-crop rotation with a nitrogen-fixing crop, often soybeans USA production uses USA production  56% animal feed  18% export (much for animal feed)  13% ethanol (alcohol for fuel)  5% High Fructose Corn Syrup  8% all other industrial and food uses  only 4% of corn grown in 1st world goes to human food directly

51. © T. M. Whitmore Maize Uses II “Invisible” food uses  Production of corn sweeteners: corn syrup  keeps foods moist and prevents them from quickly spoiling.  Less expensive than table sugar in United States due to subsidizing corn syrup production while taxing sugar imports  High fructose corn syrup (HFCS) is a modified form of corn syrup that has an increased level of fructose.  Most all soft drinks sold in USA

52. © T. M. Whitmore Maize Uses III Production of ethanol in USA  Ethanol, a type of alcohol, is mostly used as an additive in gasoline to increase the octane rating Increasingly as major fuel source:  Argued to be “greener”greener  E85 (85% ethanol/15% gasoline) E85  flexible fuel vehicles  Tax breaks Ethanol is a significant market for U.S. corn, consuming more than 1.2 billion bushels in 2004

58. From J.C. McCann Maize and Grace © Harvard University Press

59. © T. M. Whitmore Maize as food Tasty and edible in many stages of development:  immature as corn on the cob  mature as dried and ground as grain Nutrition  Process of soaking maize in water with lime (from wood ash) to soften for grinding (using a metate y mano) - changes chemical composition (nixtamalization) metate y mano  Makes some amino acids (needed to make protein) more available (especially lysine)  Increases availability of B vitamins especially niacin (cultures that rely on corn without this process suffer from nutrition deficiencies)

60. © T. M. Whitmore