In its special fall issue of 1992, Time magazine declared the hybridization of corn to be one of mankind’s greatest achievements of the last one thousand years. In 1942, Iowa farmers became the first farmers in the nation to plant their entire acreage with hybrid corn—a huge milestone considering that in 1933 less than 1 percent of the total corn acreage had been planted with hybrid corn.
Before the dawn of hybrid corn, farmers in the Corn Belt planted open-pollinated corn, rarely producing average yields of thirty bushels or more per acre. At the time, Reid’s Yellow Dent was the most widely used variety of open-pollinated corn. The 1940s, the first decade in which double-cross hybrid corn assumed national importance, witnessed the nation’s first major sustained increase in corn production. By the 1950s, hybrids widely used in the 1940s were being replaced by new and superior double-cross hybrids that could produce stronger stalks that stood well throughout the growing and harvest seasons and held heavier ears.
The development of hybrid corn led to major changes in how farming was done. Corn pickers pulled by horses had been tried in earlier years, but had not been successful in fields planted with open pollinated corn, where broken stalks and ears on the ground were too prevalent. The corn had to be picked by hand in order to maximize yields. Double-cross hybrids changed all that. Farm horses gradually disappeared. Tractors became more numerous, and the mechanical harvesting of hybrid corn soon replaced the labor-intensive practice of hand picking. By their nature, double-cross hybrids could also tolerate higher levels of fertility, and soon farmers began using more fertilizer, especially anhydrous ammonia. By the 1960s, the new single-cross hybrids had replaced the earlier double-cross varieties in the top corn-producing states, raising yield potentials even further.
But what is hybrid corn that produces over 400% increase in crop yields per acre? And how does hybrid corn differ from corn that was planted prior to its development?
Hybrid corn was the result of a new system of breeding made possible primarily thanks to two developments. These concerned understanding the physical makeup of the corn plant itself, well beyond that of the native americans, and a new system of breeding consisting of a collective series of discoveries made in the early 1990s in the science of heredity and the degree to which heredity can influence the development and function of plants.
The end result is that today seed corn is “custom built” for particular needs. Hybrids have been developed that have the capacity to produce much greater yields, have a much shorter growing season better suited to more northern climates, are resistant to insects, can withstand drought, and can tolerate glyphosate herbicides. The list of possibilities seems almost endless.