The Conundrum Of Corn


The great scientific era of corn breeding did not begin until late in the century. In 1871 Charles Darwin, working with corn, found that inbreeding a strain of corn would weaken it, but crossbreeding an inbred with another variety would revive it. William James Beal, at Michigan Agricultural College, who corresponded with Darwin, began the first controlled crossbreeding of corn and produced strong hybrid strains.

Thirty years later, George Harrison Shull, working in a Long Island laboratory, developed Darwin’s thesis. Setting out to study the workings of heredity, he chose to work with corn because it is such a handy evolutionary tool. Its chromosomes are large, easily observed and manipulated; its tassel-ear separation makes pollenization-control simple; and it carries a multitude of characteristics in its genes. In fact, next to the salivary glands of the fruit fly, corn is the favorite subject of genetic experiments. To isolate the characteristics he wanted to study, Shull inbred varieties and found, as Darwin had, that the more he refined them, the more he weakened them. However, when he crossed the puny inbred of one line to the puny inbred of another line, a procedure known as a single cross, he attained what he described as “an extraordinarily powerful hybrid … more vigorous than the best of the inbred races.” He called the phenomenon heterosis, or hybrid vigor.

Shull’s work was more or less duplicated by Edward Murray East in Connecticut, but neither pushed their results to practical use. (East went off to teach at Harvard while Shull returned to work on his first botanical love, the evening primrose.) Their hybrid did not, it turned out, produce seed in profitable amounts, but a student of East’s, Donald Jones, overcame this. He took a single-cross hybrid produced by crossing two inbreds, and crossed it with another single cross. This was a double cross, and the result was splendid—large, vigorous plants and ears that produced seed in profitable quantities. Like Robert Reid, Jones had luck on his side. There were only two single-cross strains available in the laboratory, so he had to use them. Later experimenters found that double crosses fail ninety-nine times out of one hundred. Jones happened to have the one in a hundred that would work.

It remained for a politician who has been looked on largely as an idealist and a dreamer to make practical use—and a great deal of money—out of hybrid vigor. Henry Agard Wallace’s grandfather, always called Uncle Henry, had been a Presbyterian minister who settled in Iowa after the Civil War and grew rich from intelligent farming and shrewd land buying. Eventually he became editor of Wallaces’ Farmer and preached, as his masthead proclaimed, “Good Farming, Clear Thinking, Right Living.” In 1902 he met a man whose philosophy matched his own: Perry Greeley Holden, always known as P.G. There must have been some atavistic Indian reverence for corn in P.G. Better corn would not only make men better farmers, he believed; it would also make them better men. A student of Beal’s, he had given up a professor’s post to help develop and distribute improved strains of Reid’s Yellow Dent. When he came through Iowa promoting his seed, Uncle Henry decided Iowa needed a man like him and, putting up part of the salary himself, he got the state college at Ames to take him on the faculty.

P.G. had a vision of an ideal corn: uniform ears, nine and one-half to ten and one-half inches long, with even rows and deep kernels shaped like a keystone. To help his evangelist, Uncle Henry coaxed the railroads to set up corn trains to carry P.G.’s corn and message to all farmers. Corn-growing competitions, called corn shows, became an annual event in the Midwest. Farmers would enter their best, most uniform ears. Judges, all trained to follow P. G.’s precepts, would lay them out, compare them, feel the kernels, run fingers over the ear, heft them. The best ear got ten points, the poorest only one. Winners gained cash prizes and great prestige. Getting ready for the contest, a farmer would pore over bushels of corn to match his best ears, carry them to the shows as if they were ingots of gold, and often when he got there, he would swap with other farmers to get more exactly matching ears. Sometimes he would paste kernels into the cob for evenness, soak an ear in water to make it fuller, or poke a metal rod into the cob to make it heavier.

All this made farmers more discriminating about the corn they grew. But one day in 1904, Uncle Henry’s sixteen-year-old grandson, Henry Agard Wallace, heard P.G. hold forth on show corn. Young Henry knew a good deal about plants—George Washington Carver, the famous black scientist who went to college at Ames and was a family friend, used to take him on botanical field trips. Henry asked P.G.: Would a ten-point ear of corn produce more corn than any other? Of course, P.G. replied, though he had never really looked into yield. When the boy persisted, P.G. and Henry’s father (later Warren Harding’s Secretary of Agriculture) decided he should find out for himself. They collected twenty-five ears of the best show corn and twenty-five of the poorest. On a three-acre piece of land, Henry spent a diligent summer planting and tending his fifty specimens. The harvest justified his skepticism: the highest yield came from an ear no corn-show judge would look at twice. And as a whole, the highest-ranked show ears produced less than those that ranked lowest.