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Genetic analysis of crosses among maize populations representing different heterotic patterns

Misevic, D.
Crop science 1990 v.30 no.5 pp. 997-1001
crossing, height, plant characteristics, Zea mays, plant breeding, provenance, genetic techniques and protocols, heterosis, loci, heterozygosity, homozygosity, crop yield, grains, population, Corn Belt region, Latin America, Yugoslavia
Maize (Zea mays L.) breeders are concerned with the narrowing germplasm base and the wide-spread usage of a single heterotic pattern. The primary objective of this study was to estimate genetic parameters for a set of seven elite maize populations from the USA, Yugoslavia, and Latin America for selection of base populations in recurrent selection programs. Populations per se, population crosses, populations per se selfed, crosses selfed, and the hybrid check B73 X Mo17 were grown in a randomized complete-block design experiment with four replications at three locations in 1987 and 1988. Contributions of homozygous (ak) and heterozygous (dk) loci to population means, mean of random homozygous inbred lines (micro), and heterosis effect (hkj) with its subdivisions (average heterosis, population heterosis, and specific heterosis) were estimated. Contributions of heterozygous and homozygous loci to population means accounted for the largest and smallest portions of variation among diallel entries, respectively, for both grain yield and plant height. Heterosis accounted for 11.3 and 8.7% of the total among diallel entries sum of squares for grain yield and plant height, respectively. BS11(FR)C7 had the highest population per se yield due to its large contribution of both homozygous and heterozygous loci, and the highest estimate of inbreeding depression for grain yield. BSSS(R)C7 had the highest estimate of heterosis effect, but lowest per se yield due to low ak and dk estimates. The highest yield and the highest specific heterosis estimates were found for crosses BS11(FR)C7 X BS16(S2)C3 and BSSS(R)C7 X ZPEP. BSSS(R)C7 X ZPEP had the highest overall heterosis effect.