University of Minnesota, Agr. Exp. Station
Bulletin No. 11, 89-93 (June, 1890)

Improving Corn — Cross Fertilization and Selection
Willet M. Hays

During the past two seasons the writer has studied and performed experiments, with a view to finding the best methods of growing, cross-fertilizing, and selecting corn, looking to the development of definite good varieties for each locality, and each particular use, as grain, fodder, etc. Progress in this kind of work is necessarily slow. Some interesting notes have been made upon crosses produced, some of which, together with a few facts suggested, and also hints regarding methods of raising corn for seed, are here given. I cannot refrain from repeating that along the northern edge of the corn belt no such clearly defined varieties are found as farmers have developed in sections farther south, where corn is King. Here the small patches grown are often of several varieties planted together, where they naturally mix, and the seed is selected without regard to any definite type. Where corn receives more attention many farmers have learned, from long experience, that care in selecting and preserving seed is of great importance. Here there is even more need of thorough work in developing varieties, since we have so little seed which will really ripen, and is adapted to producing the best crop of ears and fodder.

In 1888, ears of numerous varieties were fertilized with pollen from other varieties, bags being placed over the ears to prevent the introduction of other pollen. As an example, pollen from a plant of an eight rowed white or yellowish Flint variety (No. 22, Squaw Corn) was placed on the silks of an ear of twelve rowed white Sweet corn (No. 35, Crosby's Early). The resulting ear had, of course, the general form of the Sweet variety, since the pollen from another plant affects only the grains the first season, the cob being merely a receptacle for the kernels. The grains, however, on this ear, are three-fourths like the male parent, resembling Flint grains, while the remaining one-fourth look like Sweet grains. There is no distinct gradation between the two kinds of grains, each one being in appearance either like Sweet corn or like kernels of Flint; Some of the latter showing only a slight tendency to wrinkle on the top.

A dozen or more of each of the two kinds of grains from this ear were planted the past season in separate, isolated places. The sweet kernels produced ears in form and size closely resembling Crosby's Early; a few showing no Flint grains; while most of them had a few, or several grains, in appearance like Flint corn. Most of them had twelve rows, like the female parent, while a few had eight, like the Flint, and one stood between the two in this respect, having ten rows of grains on the cob. The Flint like kernels produced ears much more slender, and longer, resembling the Flint parent. A few, however, were in form nearly like the Sweet corn, and with ten rows; or, with the two added rows reaching only part way from the butt. While the Sweet grains produced ears nearly all Sweet, the kernels of Flint produced ears with about the same proportion of the two kinds as were on the parent ear produced by the cross, viz.: one-fourth Sweet and three-fourths Flint.

Another example is had in an ear of a small yellow Dent variety (No. 13 Pride of the North), fertilized in '88 with pollen from a single plant of medium sized white Dent (No. 5, Rustler). The resulting ear had yellow and white grains in the proportion of one of yellow to two of white; though, in this case, the colors seemed to be more or less mixed in the same kernel. A dozen of the yellow kernels planted in an isolated place, produced ears resembling Pride of the North, excepting one ear, which closely resembled the white parent, both in form and in color. Several of the lighter colored grains were also planted in an isolated place. Most of the dozen resulting ears were nearly white, one nearly all yellow, while the light colored ears had several, or even a few dozen, yellowish grains. Both in form of ear and grain, the characteristics of the white parent predominated.

These results most clearly show how easily variations in corn can be made and “fixed.” Radical results like these, in influencing the form of ear, kind of grain, etc., from the first season, illustrates that only a few years of careful selection are necessary to develop and fix a type of corn.

AN INTERESTING CASE OF CROSS-FERTILIZING CORN.

The engraving of corn here with, represents a very interesting case of reversion to previous more or less remote ancestors. In a field in the northeast part of the Station Farm, was planted in 1888, Mercer Yellow Flint corn (Fig. 1). Thirty rods south, across a field planted to small grains and root crops, were planted a few rows of Black Mexican Sweet corn (Fig.2).

When husking the field of Flint corn, the laborers were told to save any ears having black grains, as it was thought some of the pollen from the Black Mexican would be carried across the field, and cross-fertilize grains of the Flint. Several ears of Mercer Flint were found, each with one or a few black grains. In no case had the Sweet variety given these grains the rough form of Sweet corn, but merely the color, while in form and hardness they resembled the Flint grains. A dozen of these dark colored grains were planted in the vineyard in 1889, far enough away from other growing corn so that no foreign pollen reached the plants. Three or four dozen ears were produced, every one of which was a proof that the pollen from the Black Mexican corn was the male parent which had fertilized the dark colored grains on the ears of Flint the previous year. Every ear had a few or many grains exactly similar in appearance to grains of Black Mexican Sweet. These grains are shown in Fig. 3, a few of which are marked B. S. The yellow Flint corn impressed its characteristics of form and color on some grains, a few of which are marked Y. F. The smooth yellow grains all have the appearance of Yellow Flint corn, and the form of the ear and cob also seemed to resemble this parent, though a few had twelve rows of grains. The Flint parent had eight rows, while the Sweet parent had, as a rule, twelve rows. Besides the Yellow Flint grains and the Black Sweet grains, above mentioned, there are Yellow Sweet, Y. S., grains, and Black Flint, B. F., grains, Even more surprising is it to find a few white Sweet grains, W. S., and a few white Flint grains, W. F., on nearly every ear. The color of the black Flint grains can be explained by assuming that the Flint parents form was predominant, while the color of the Sweet prevailed. And in case of the yellow Sweet grains we can assume that the form of the Sweet grains and the color of the Flint predominated. But in the case of the white Sweet grains, no such assumptions can be made, and no better presumption appears than that the black Sweet corn had, in no distant generation, been mixed with a very light colored variety of Sweet corn; and, in case of the white Flint grains, the form is after the form of the yellow Flint parental stock, and the color may have come from a previous ancestor of white Flint, or even of white Sweet. A still further, and even stronger proof of this “breeding back,” or taking the qualities of ancestors more or less remote, is the fact that on several of the ears were grains of Sweet corn showing a reddish, or flesh colored tinge. This reddish color is peculiar to a class of Sweet corn called Early Narragansett, and the color here may be from some reversion to previous ancestors of this kind of corn, with which the Black Mexican grand-parent may have been mixed.

The practical lesson taught by the example of an ear with six or seven kinds of corn shown, is that we must “breed" our corn for a number of years pure, and carefully select the seed, according to some type, if we would have distinct varieties. The principles of heredity may find as practical application in breeding corn as in breeding cattle. This is a good illustration of the value of pedigrees, and also plainly and forcibly illustrates the value of thoroughbred ancestry in raising animals. Here both parents probably had recently been crossed with different varieties, and the different ancestral characteristics reappeared, and determined the form or color, or both, of some of these kernels. Further, we have illustrated here the effect of making radical crosses. Some of the young grains resemble one parent, and some the other, while yet others resemble parents more remote. The same thing occurs here as when Jerseys and Short Horns of other especially beefy type are bred together. In that case, some veritable Jerseys for performance at the pail, are produced, and others, like the Short Horns, are adapted for beef. Others revert to remote ancestors, or in some way manifest a combination of the inherited qualities of their ancestors, and are in appearance quite unlike either parent. So, in corn growing, it pays to keep seed pure. Retain one intelligently selected type, and by cultivation and selection, and even by cross-fertilization, improve and “fix” the desired type.

Plate showing two parent ears. Fig. 1, Yellow Flint; Fig. 2, Black Sweet; and the result of the cross, Fig. 3.