Relationships between agronomic traits of maize (Zea mays L.) parental lines and traiits of hybrid progenies are important for breeders. If significant improvements in source populations are made by such procedures as recurrent selection, a breeder should know how such changes affect relationships between traits of parental lines and hybrid progenies. Correlations between agronomic traits and grain yield among random S1 lines and S1 line testcrosses from the original Iowa Stiff Stalk Synthetic (BSSSC0) maize (Zea mays L.) population, two improved strains of BSSS [BS13(S)C3 and BSSS(R )C9], and the intermated cross between the two improved populations [BS13(S)C3 x BSSS(R)C9], were calculated to determine changes that occurred with recurrent selection in BSSS. Previous evaluations of these populations showed significant changes for agronomic traits and for genetic variances among S1 lines and hybrid progenies. Both S1 lines and S1-line testcrosses showed significant correlations between agronomic traits and grain yield in etch population. No consistent trend in phenotypic correlations between the unimproved and improved populations were observed. Phenotypic correlations between S1-line traits and testcross yield were too small to he of predictive value in a selection program.
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This article is published as Walters, S. P., W. A. Russell, and K. R. Lamkey. 1991. Comparisons of phenotypic correlations among S1 lines, and their testcrosses, from four Iowa Stiff Stalk populations of maize. Maydica 36:39-44.