Zea mays L., Corn, Corn Breeding, Breeding methods, Recurrent selection
Most maize (Zea mays L.) breeders practice visual selection among lines during inbreeding, but may not be certain of the effectiveness of such selection. Visual selection among and within 1,636 S1 lines of maize derived from 'Lancaster Composite' was used to select 200 S2 lines, and a random set of 200 S2 lines also was developed. Yield trials of the 400 S2 lines in three environments and their testcrosses to (B73 x B84) in four environments were conducted to determine whether visual selection was effective in choosing high-yielding and agronomically desirable lines with superior combining ability. Grain yield of the visually selected S1 lines (3.11 Mg ha-1) was significantly (P<0.05) greater than that of the unselected lines (2.94 Mg ha-1), but there was no difference in testcross means. Visually selected S1 lines had slightly greater mean grain moisture and slightly less mean stalk lodging than unselected lines in individual environments. Testcrosses of visually selected lines had greater grain moisture and less stalk lodging than testcrosses of unselected lines in individual environments. Estimates of genetic variance, heritability, and gain from selection were not consistently affected by visual selection. Many superior S2 lines and testcrosses were unselected lines, showing that visual selection failed to identify many desirable genotypes. Our results suggest that visual selection should not be used to attempt to select the most superior genotypes, but should emphasize discarding of undesirable genotypes before yield testing.
Proceedings of the Iowa Academy of Science
©1986 Iowa Academy of Science, Inc.
Clucas, C. P. and Hallauer, A. R.
"Selection Among and Within S1 Lines of Maize on S2 Line and Testcross Performance,"
Proceedings of the Iowa Academy of Science, 93(4), 178-183.
Available at: https://scholarworks.uni.edu/pias/vol93/iss4/5