Bureau of Plant
Industry-Bulletin No. 191 (October 22, 1910)
The Value of First-Generation Hybrids in Corn
G. N. Collins
PREVIOUS EXPERIMENTS WITH FIRST-GENERATION HYBRIDS
EXPERIMENTS IN MICHIGAN.
That the immediate result of crossing two varieties is to increase the yield was shown by definite experiments as early as 1878 by Dr. W. J. Beal, of the Michigan Agricultural Experiment Station. The plan for such experiments had been outlined two years before, in 1876, the same year that Darwin published his classical work on self and cross fertilization in plants, but without knowledge of Darwin's results. Doctor Beal's first statement was as follows:
|b Beal, W. J. Report, Michigan
Board of Agriculture, 1876, p. 206.
To improve or infuse new vigor into varieties (or races I should more properly call them) I propose in case of corn and some other seeds to get seeds from remote parts where it has been grown for some years, and plant near each other and mix them.b
Even at this early date Doctor Beal appreciated the fact that the benefits were largely confined to the first generation.
|c Loc. cit.|
The good results of such crossing will last for several years, though most apparent the first year.c
The nature of the first experiment and its relation to the similar experiments of Darwin are shown in the following quotation:
From several different sources in remote parts of our State I obtained white dent corn and yellow dent corn for seed. So far as possible I obtained good seed from men who had raised the corn for ten or more years in succession on the same farm.
|a Beal, W.
I. Report, Michigan
Board of Agriculture, 1877, p. 56.
I crossed some white dent from one locality with pollen from white dent obtained in a remote locality. This may add vigor to the race, though it will probably not otherwise change the race. The plan was conceived by me about a year ago, and several months afterwards the same kind of experiments were reported on many species of plants by Mr. Charles Darwin, of England. The favorable results of many experiments there given are quite remarkable.a
In 1880 the representatives of five different agricultural schools entered into an agreement to test by a uniform experiment at their several stations this method of corn improvement. Each experimenter was to report his experiment to the other parties to the agreement.
The details of this agreement are given as follows:
Each man in his own State shall select two lots of seed corn which are essentially alike in all respects. One should have been grown at least for five years (better ten years or more) in one neighborhood and the other in another neighborhood about 100 miles distant. In alternate rows plant the kernels taken from one or two ears of each lot. Before plowing, thin out all poor or inferior stalks. As soon as the tassels begin to show themselves in all the rows of one lot, pull them out, that all the kernels on the ears of those rows may certainly be crossed by pollen from the other rows. Save seed thus crossed to plant the next year by the side of seeds of each parent. Seeds of one parent can be obtained from the rows not topped. Seeds of the other parent should be planted by themselves to get pure seeds of the same year.
For the second year, select two pieces of ground, each as even as possible, about 4 by 8 rods in extent. Manure it evenly as possible with barnyard manure if any fertilizer is employed. Plow the ground without bed or ridge furrows or, if either occur, plant so that a row of each comes at equal distance from the ridge or bed furrow. Take no unusual pains to make the ground very rich or to cultivate better than usual. Keep the cultivation alike on all parts of the plate as nearly as possible.
On one of these plats plant some of the crow seeds in alternate rows with seeds of one of the parents. On the other plat plant the crossed seeds in alternate rows with the other parent. Seeds of each parent raised the previous year will thus be tested with seeds of the same age from the cross. Take notes of the time in which the plants in each row come up and of the appearance from time to time. Make plats of the corn and be careful to keep everything straight. Take notes of the time of maturing, and when matured cut near the ground the hills of each row and shock separately. After it is cured, husk and weigh the ears and the stalks separately of each row. It would be well to weigh the dried shell corn of each row separately. In the report give the weight of corn and stalks of each row separately, then a summary of the weights of each parent and the crossed stalk. Each experimenter shall report his experiments thus made to each of the other persons entering into this arrangement.
|b Ibid., 1880, pp. 287-288.|
A similar experiment was made at the agricultural college in 1878. In this the advantage shown by crossing of corn over that not crossed was as 151 exceeds 100, and in the case of black wax beans it was as 236 exceeds 100. In a similar experiment made during the past two years at the agricultural college, the corn from seed of crossed stock exceeded that not so crossed as 109 67/100 exceeds 100, or nearly 10 per cent in favor of crossed stock. The experiment was quite carefully made and I do not consider this result as purely accidental.b
Alter a lapse of more than thirty years it is hardly possible to improve or refine the method of experimentation as outlined by this pioneer. His method of comparing yields by alternate-row plantings was also more perfect than that of his successors and is again coining into use as the best that has yet been devised.
In 1881 Doctor Beal made another cross, between two varieties from Oakland and Allegan counties, respectively, and reported the results of the cross as follows:
The Oakland County seed corn was the better of the two. Owing to an accident we failed to raise any pure Allegan County seed in 1881. The "crossed corn" was only compared with pure Oakland County seed raised last year at the college.
|a Beal, W. J. Report, Michigan
Board of Agriculture, 1881-2, p. 136.
In the spring of 1882, on good soil in a portion of the vegetable garden, three rows of "crossed seed" were planted in rows alternating with three other rows of pure Oakland County seed of 1881. By an oversight each row of each lot was not kept separate. The pure seed yielded 57 1/2 pounds in the ear; the "crossed seed" yielded 69 1/2 pounds in the ear. In other words, the crossed stock exceeded the pure stock as 121 exceeds 100, nearly.a