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Hybrid corn is created by cross-pollinating inbred lines and accounts for over 90% of US corn production. Traditional corn farming involved selecting desirable traits and inbreeding. Hybrid corn was discovered in 1908 and improved with four-way crosses, but genetic uniformity increased susceptibility to disease. Modern hybrid corn is crossed with open-pollinated corn to retain genetic diversity.
Hybrid corn, also known as hybrid corn, is an agricultural product created by cross-pollinating several inbred lines of corn. It accounts for over 90% of all corn grown in the United States due to its large size and uniform appearance. The processes used to cross plants were first understood and documented by Gregor Mendel in 1860, but were not widely applied to agriculture until the 1930s.
Before the discovery of hybrid corn, traditional corn farming was very simplistic. Farmers would select a group of maize plants that shared a desirable trait, such as disease resistance, large size, height, fast growth, or appearance, and then try to amplify those traits by planting those plants together and allowing them to reproduce. Incidental pollination was very common, so the initial plants in the group were not always just those selected by farmers. Over the course of several generations of inbreeding, this group of plants would have grown into one strain, sharing a similar gene pool and physical traits.
In 1908, a researcher discovered that if he took two inbred lines and crossed them, the resulting hybrid corn was a much larger and hardier plant than either inbred line had ever produced. The agricultural implications were staggering, and farmers could suddenly produce far more corn than they had been able to produce before. Subsequently, another researcher improved the crossing process by suggesting that two hybrids could be further crossed to produce a plant with high production and a high percentage of viable seeds. This type of hybrid became known as a four-way cross. However, four-way crosses were difficult to develop, because for every four inbred strains there were numerous possible ways of combining them, each of which had to be cultivated and compared with the others to select the most productive and viable.
The main disadvantage of growing hybrid corn would only be discovered many years later, when farmers discovered that the uniform appearance brought with it a dangerous genetic uniformity. The more effort farmers put into making sure plants are all the same, the more genetically similar they made them. Double-crossing lines avoided many of the disadvantages created by traditional inbreeding, but greatly increased susceptibility to disease. Without the genetic diversity to protect a hybrid corn crop, a single pathogen could spread across a field, jumping from one plant to another, infecting everything. Modern hybrid corn counteracts this problem by crossing hybrid lines with open-pollinated corn to produce varieties that have specific characteristics but retain some degree of genetic diversity.
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