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Plant Breeding, Genetics, & Genomics

Plant Breeding

Plant breeding is the process of applying knowledge to plant genetic resources, for the purposeful creation of useful plant varieties for food, fiber, and other essentials, and for beauty. In the early 20th century, plant breeders realized that Mendel's findings on the nonrandom nature of inheritance could be applied to seedling populations produced through deliberate pollinations to predict the frequencies of different types. From then on, progress in plant breeding has been continuous.

By the 1920s, statistical methods were developed to analyze gene action and distinguish heritable variation from variation caused by environment. Hayes and Garber, in their classic 1927 text, could wrote, “A knowledge of laws of heredity, biometrical tools, and field and laboratory technique, together with an understanding of the genetics of the particular crop which is being studied, are an absolute necessity for the trained breeder.”

By the 1930s, these trained breeders had achieved previously unimaginable yield gains with hybrid corn, using a counterintuitive procedure that earlier plant breeders could not have designed. Investment in plant breeding applying the new genetic discoveries was becoming evident in what was to be a sustained rise in on-farm yields. Plant breeders went on to develop methods to concentrate genetic variation so that it could be selected more efficiently, to select for yield stability, and to advance several required traits at once.

At the start of the 21st century, U.S. Americans were accustomed to increasing crop yields, but this was, in fact, historically unprecedented and astonishing to those who first observed it. In the rest of the developed world, most of the yield increases that began in the United States in the 1930s came after WWII; and in developing countries, after the 1960s, with the Green Revolution.

In much of Africa, crop yields have not yet increased or are even decreasing. Over the century, U.S. yields of barley, oats, dry beans, and alfalfa doubled; yields of soybeans, wheat, cotton, and peanuts tripled; and yields of corn, potatoes, and rice increased fourfold, fivefold, or more. In general, the greater the investment in the crop, the greater was the gain.

In most crops, about half of the increased yield was genetic gains from plant breeding (Fehr, 1987 and 1993); the remainder was because of cultivation practices such as increased use of commercial fertilizers and closer spacing between plants in a field that became possible with mechanization. Human population grew during the century, by more than four billion (or a little under 3.5-fold). An adequate daily diet became a possibility for a far greater proportion of the population than in any previous era. In addition, countries that successfully invested in plant breeding could afford to limit land in food production, allowing the conscious preservation of natural habitat.

Researchers at the USDA's Economic Research Service estimated the value of improvement in five crop varieties. The net economic effect from genetic enhancements is an overall increase in U.S. economic welfare of roughly $115 million per year. At the world level, global economic welfare gains in excess of $300 million per year: large effects when compared with the July 24, 2007 mates.

Sources:

  • Hayes, H. K., and R. J. Garber. 1927. Breeding crop plants. McGraw-Hill Book Company, Inc., New York and London. 438 pp.
  • Fehr, W. R. 1987 and 1993. Principles of cultivar development. Vol. 1. Macmillan Publishing Company, New York. 536 pp.
  • Staff of the USDA ERS Resource Economics Division; Resources, Technology, and Productivity Branch.

 

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