CHAPTER ONE
- OVERVIEW OF MAIZE
- ORIGIN
Maize is known in many English speaking countries as Corn. It is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times (Green,1999). The leafy stalk produces ears which contain seeds called kernels, though technically a grain. The Olmee and Mayons cultivated it in numerous varieties throughout central southern Mexico between 1700 and 1750, the crop spread through America (Boyd et al.,2006). The region developed a trade network based on surplus and varieties of maize crops. After the European contact with the America in the late 15th and early 16th centuries, explorers and traders carried maize back to Europe and introduced it to other countries. Maize spread to the rest of the world due to its ability to grow in diverse climates (Piperno et al., 2009).The term “Maize” was derived from the Spanish form of the indigenous Taino word for the plant, Maiz. It is known by other names around the world. The term “Maize” was used in the United Kingdom and Ireland, where it is now usually called “sweetcorn”, a common crop known to people there (Cudderford,1995). Corn was originally the English term for any cereal crop. In North America, its meaning has been restricted since the 19th century to maize as it was shortened from “Indian corn”. The term Indian corn now refers specifically to multi-coloured “field corn” (flint corn) cultivars (Herman and Larkins,1999). In scientific and formal usage, “maize” is normally used in a global content. In English speaking countries, the word corn is often used in culinary contexts, particularly in naming products such as popcorn, cornflakes and baby corn. In Southern Africa, maize is commonly referred to as mielle or mealie, from the portugese millo. It is called Masara in Hausa, Oka. In Igbo, and Agbadoin Yoruba. Maize is used in agricultural and scientific references (Fernandez-Armisto, 2001). Maize is the most widely grown grain in the world with 800 million metric tons produced annually. Maize is domesticated variant of teosinte. The two plants have dissimilar appearance, maize having a single tall stalk with multiple leaves and teosinte being a short, bushy plant. The difference between the two is largely controlled by differences in just two genes. Several theories had been proposed about the specific origin of maize in Mesoamerica (Ranere et al., 2009)
- It is a direct domestication of a Mexican annual teosinte Zea mays, spp. parviglumis, native to the Balsas River valley in South-Eastern Mexico, with up to 12% of its genetic material obtained from Zea mays spp. mexicana through introgression (Dunn, 2005).
- It has been derived from hybridization between a small domesticated maize (a slightly changed form of a wild maize) and a teosinte of section Luxuriantes, either Z. luxurians or Z.diploperennis (Sluyter et al., 2006)
- It has undergone two or more domestications either of a wild maize or of a teosinte. (The term “teosinte” describes all species and subspecies in the genus Zea, excluding Zea mays ssp. mays.)
- It has evolved from a hybridization of Z. diploperennis by Tripsacum dactyloides (Kriz, 2009).
In the late 1930s, Paul Manglesdorf suggested that domesticated maize was the result of a hybridization event between an unknown wild maize and a species of Tripsacum, a related genius. This theory about the origin of maize has been refuted by modern genetic testing, which refutes Mangelsdorf’s model and the fourth theory listed above (Wilkes and Garrison, 2004). The teosinte origin theory was proposed by the Russian botanist Nikolai Ivanovich Vavilov in 1931 and later the American Nobel Prize winner, George Beadle in 1932. It is supported experimentally and by recent studies of the plant genomes (MacNeish et al.,2000). Teosinte and maize are able to cross breed and produce fertile offspring. The domestication of maize is of particular interest to researchers, archaeologists, geneticists, ethnobotanists, geographers, etc. The process is thought by some to have started 7,500 to 12,000 years ago.
