The Historical Development of High-Yield Crops (Genetics & Inherited Conditions)
No one knows for certain when the first crops were cultivated, but by six thousand years ago, humans had discovered that seeds from certain plants could be collected, planted, and later gathered for food. As human populations continued to grow, it was necessary to select and produce higher-yielding crops. The Green Revolution of the twentieth century helped to make this possible. Agricultural scientists developed new, higher-yielding varieties, particularly grains that supply most of the world’s calories. In addition to greatly increased yields, the new crop varieties also led to an increased reliance on monoculture, the practice of growing only one crop over a vast number of acres. Current production of high-yield crops is extremely mechanized and highly reliant on agricultural chemicals such as fertilizers and pesticides. It also requires less human power, and encourages extensive monocropping.
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Methods of Developing High-Yield Crops (Genetics & Inherited Conditions)
The major high-yield crops are wheat, corn, soybeans, rice, potatoes, and cotton. Each of these crops originated from a low-yield native plant. The two major ways to improve yield in agricultural plants is to produce a larger number of harvestable parts (such as fruits or leaves) per plant or to produce plants with larger harvestable parts. For example, to increase yield in corn, the grower must either produce more ears of corn per plant or produce larger ears on each plant. Numerous agricultural practices are required to produce higher yields, but one of the most important is the selection and breeding of genetically superior cultivars.
Throughout most of history, any improvement in yield was primarily based on the propagation of genetically favorable mutants. When a grower observed a plant with a potentially desirable gene mutation that produced a change that improved some yield characteristic such as more or bigger fruit, the grower would collect seeds or take cuttings (if the plant could be propagated vegetatively) and propagate them. This selection process is still one of the major means of improving yields. Sometimes a high-yield cultivar is developed that has other undesirable traits, such as poor flavor or undesirable appearance. Another closely related cultivar may have good flavor or desirable appearance, but low yield. Traditional breeding techniques can be used to form hybrids between two...
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Genetic Modification (Genetics & Inherited Conditions)
The advent of recombinant DNA technology has brought greater precision into the process of producing high-yield cultivars and has made it possible to transfer genetic characteristics between any two plants, regardless of how closely related. The first step generally involves the insertion of a gene or genes that might increase yield into a piece of circular DNA called a plasmid. The plasmid is then inserted into a bacteria, and the bacteria is then used as a vector to transfer the gene into the DNA of another plant. This technology has resulted in genetically modified crops such as “golden rice” (fortified with vitamin A), herbicide-resistant soybeans, and new strains such as triticale, which promise to ameliorate world hunger at the same time that they threaten to reduce biodiversity and alter other plants through genetic drift.
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Impact and Applications (Genetics & Inherited Conditions)
As the human population grows, pressure on the world’s food supply will increase. Consequently, researchers are continually seeking better ways to increase food production. In order to accomplish this goal, advances in the production of high-yield crops will have to continue at a rapid rate to keep pace. New technologies will have to be developed, and many of these new technologies will center on advances in genetic engineering. It is hoped that such advances will lead to the development of new high-yield crop varieties that require less water, fertilizer, and chemical pesticides.
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Further Reading (Genetics & Inherited Conditions)
Acquaah, George. Principles of Crop Production: Theory, Techniques, and Technology. 2d ed. Upper Saddle River, N.J.: Pearson Prentice Hall, 2005. Includes chapters on crop improvement and transgenics in crop production, as well as specific information about ten crops.
Avery, Dennis T. Saving the Planet with Pesticides and Plastic: The Environmental Triumph of High-Yield Farming. 2d ed. Indianapolis: Hudson Institute, 2000. Argues that high-yield agriculture using chemical pesticides, fertilizers, and biotechnology is the solution to environmental problems, not a cause of them, as environmental activists have averred.
Bailey, L. H., ed. The Standard Cyclopedia of Horticulture. 2d ed. 3 vols. New York: Macmillan, 1963. Since the 1920’s, a standard reference that still offers basic information; its original subtitle reads: “a discussion, for the amateur, and the professional and commercial grower, of the kinds, characteristics and methods of cultivation of the species of plants grown in the regions of the United States and Canada for ornament, for fancy, for fruit and for vegetables; with keys to the natural families and genera, descriptions of the horticultural capabilities of the states and provinces and dependent islands, and sketches of eminent horticulturists.”
Chrispeels, Maarten J., and David E. Sadava. Plants, Genes, and Crop Biotechnology. 2d ed. Boston: Jones and...
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Web Sites of Interest (Genetics & Inherited Conditions)
Center for Global Food Issues. http://www.cgfi.org. An American organization that advocates high-yield farming and conservation; contains additional information about high-yield farming and conservation.
Center for Global Food Issues, Growing More Per Acre Leaves More Land for Nature. http://www.highyieldconservation.org. In 2002, a group of food, environmental, farming, and forestry experts signed a declaration in favor of high-yield conservation, arguing that intensive, high-yield farming and forestry play a critical role in wildlife habitat conservation. This site contains the declaration, biographies of its signers, and background information on high-yield conservation.
Food and Agriculture Organization of the United Nations. Biotechnology in Food and Agriculture. http://www.fao.org. Addresses the role of biotechnology in worldwide food production.
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