Maize Essay ⋆ Environment Essay Examples ⋆ EssayEmpire

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Maize (zea mays ), also known as corn, is one of world’s major cereal grains along with wheat and rice. It was domesticated as long ago as 12000 B.C.E. from a tropical grass in the Americas, where it became the foundation of agriculture for the Mayans, Incans, Aztecs, and other American indigenous groups. After European contact with the Americas, maize spread throughout the world, becoming extensively grown in former European colonies from Africa to Asia and in eastern Europe. Today the United States remains by far the top producer of corn, followed by China, Brazil, Mexico, and Argentina. Maize is still a staple in subsistence communities in Mesoamerica.

Maize is a tall grass-like plant that grows from six to twenty feet tall and produces two to six ears of corn per plant. From the top of the maize plant emerges a tassel-like inflorescence of male flowers. Along the stalk several ears emerge with the silk, the elongated stigma of a female flower. Maize is an allogamous (cross-pollinating) plant; each individual fruit on an ear of corn is formed when wind-blown pollen from the tassel lands on the silks. Maize is a C4 plant, meaning that its photosynthetic pathway is different from most crop plants, which are typically C3. This allows a corn plant to produce more dry matter per unit of water.

There are several hypotheses about the origins of maize domestication, which is often cited as one of the greatest achievements in human ingenuity. One theory suggests that indigenous populations domesticated maize from a wild, sexually compatible relative called teosinte. Another argues that it was a cross of teosinte with another wild relative of maize, either Zea diploperennis or Zea luxurians.

The development of hybrid corn at the beginning of the twentieth century was a watershed event for plant breeding. Employing the principles of the newly rediscovered Mendelian genetics, George Shull coined the term heterosis in 1914. Also known as hybrid vigor, heterosis happens when the cross of two inbred lines yields more than either of the individual parent lines. In 1917 Donald Jones discovered that a cross of two hybrids exhibited even more hybrid vigor.

While hybrid seed yielded significantly more, hybrid seed does not breed true, so farmers must return to the seed producer instead of saving seed, an age-old practice of farmers. As pointed out by Jack Kloppenburg, Jr., this hastened the process of seed commodification. Before the advent of hybrid seed, commercial enterprises in seed production were less profitable because once an initial sale was made, the farmer only had to save some seed from his crop to grow the next generation. But hybrid seed decoupled the grain from the seed and by the 1930s hybrid seed production was controlled by a handful of large seed companies including U.S. Secretary of Agriculture Henry Wallace’s Pioneer Hi-bred. By 1965 95 percent of corn was grown with hybrid seed produced in the private sector. By this time public sector research in plant breeding was seen as redundant and unnecessary, and research was subordinated to private companies.

This had several unanticipated consequences. To effectively mechanize the harvest, maize ear should fall in approximately the same place on each stalk in a field. Plant breeders turned to making uniform plants that were suitable for mechanization. This led to a reduction in the genetic diversity of the plants being grown, making them susceptible to disease and pest outbreaks, often necessitating the application of pesticides. The significant quantities of agro-chemical fertilizers and pesticides applied to corn grown in the Midwest have been cited as part of the cause of a large dead zone off the Mississippi River Delta.

The massive increases in maize yields in the 20th century have turned the crop into the foundation of the industrial food system. Maize is used to produce citric acid, xanthum gum, lecithin, high fructose corn syrup, and many other foodstuffs that comprise the modern industrial food system. A significant portion of the corn grown in the United States is used as feed at the top of the cattle commodity chain. Another significant amount is used in ethanol production.

Much of the maize grown today is grown through advances in genetic engineering, where it has been the subject of considerable controversy. The StarLink™ controversy happened when a genetically engineered variety of maize not approved for human consumption made its way into several brands of processed tortillas. Even though StarLink™ has not been grown since 2001, it is still found by inspectors of Japanese imports of corn. Corn engineered with the DNA segment that expresses endotoxins from the soil organism Bacillus thuringiensis (Bt) was at the center of the monarch butterfly controversy when it was asserted that milkweed dusted with Bt caused higher mortality rates when fed to monarch butterfly larvae.

Perhaps one of the most serious of the concerns about genetically engineered maize regards gene flow to wild relatives and landraces in Mexico, the center of crop-wild diversity. In 2001 a study by two Berkeley scientists found that transgenic traits were found in Mexican landraces grown by indigenous farmers despite a moratorium on genetically engineered maize in that country.

Bibliography:

Jack Kloppenburg, Jr., First the Seed: A Political Economy of Plant Biotechnology 1492-2000 (Wisconsin, 2004);
Arturo Warman, Corn and Capitalism: How a Botanical Bastard Grew to Global Dominance (University of North Carolina Press, 2006).