Relation of selfed strains of corn to F1 crosses between them
1927
Nilsson-Leissner, G.
The relation between 22 selfed lines of corn and 100 F1 generations of crosses between them has been investigated. The lines had been selfed from 4 to 17 generations and from a comparison with brother-sister mated strains of the same descendance they appeared to be fairly homozygous. Certain lines, when mated with any one of the other strains, on an average, gave high-yielding F1's, while others gave low-yielding F1's. Correlations between the average expressions of certain characters in the two parental lines and the expressions of the same characters in the F1 generations have been computed as indicated below. (...) Multiple correlations of yield of F1 crosses in relation to the yield, length of ear, number of kernel rows, percentage of second ears, and height of plant of the average of each two parental lines were calculated in series I for dent and flint corn strains separately. In the dent corn the coefficient was +0.6687, in the flint corn +0.8240. These multiple correlations account for about 25% of the variability in yield of the dent corn crosses and about 43% of that of the flint corn crosses. If soil heterogeneity had been eliminated, still higher percentages could have been expected. The results presented here have demonstrated that in material of this nature selection among the selfed lines for the characters desired is of value and that crosses between the more vigorous selfed lines yield better, on the average, than crosses between less vigorous lines. It is concluded, therefore, that selection of the most vigorous selfed lines for the production of F1 single or double crosses and synthesized varieties is desirable. The only method of learning the better F1 combinations is by actual trial.
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