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A comparison of selfed lines of corn and first generation crosses between them

Jorgenson, L., Brewbaker, H.E.
Agronomy journal 1927 v.19 no.9 pp. 819-830
crossing, Zea mays, inbred lines, self-pollination
An investigation has been made of 10 selfed lines of maize within a variety and the F1 hybrids between them. These lines had been selfed from three to four generations but appeared to be relatively homozygous on the basis of a comparison of the selfed and sib-pollinated lines. 2. Both high and low yielders were obtained among the hybrids of each of the selfed lines, but some are distinctly superior as parents of crosses. 3. Positive and significant correlations were obtained between the following characters of the parents and the same characters of the F1 hybrids. All of these characters, with the possible exception of number of kernel rows per ear, are expressions of vigor. The more important correlation coefficients are as follows (...). 4. A multiple correlation was calculated with yield of the F1 as the dependent variable and the characters of length of ear, diameter of ear, number of kernel rows per ear, height of plants, and yield in grams per hill of the parents as the independent factors. The correlation was 0.6074. These characters of the parental lines were found to account for about 20% of the variability of yield of the F1 hybrids. 5. It is concluded that the selection of the most vigorous selfed lines for the production of single and double crosses or synthetic varieties is the proper procedure for practical corn breeding. All combinations of selfed lines may be studied in order to determine which ones will perform best in double crosses or synthetic varieties.