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Selection of donor lines to improve parents of single crosses and the relationship between inbred per se and hybrid performance are major concerns of corn ( Zea mays L.) breeders. We attempted to use molecular marker technology to address these concerns. Our specific objectives were to evaluate methods of using molecular marker data to (i) identify parents useful for improving single cross hybrid and (ii) compare marker genotypic means measured at the inbred level to those measured at the hybrid level. Performance data from a diallel cross among 14 corn inbreds were used. Molecular marker data were obtained on the 14 inbreds for 14 allozyme and 52 restriction fragment length polymorphism loci. Number of unique marker alleles in a donor inbred was not a good measure of the value of the donor for improving a single cross. A donor value calculated using genotypic means for loci that showed significant associations with grain yield was highly correlated with μG, a measure of the value of a donor. Means of homozygous marker genotypes measured at the inbred level were significantly correlated with means measured at the hybrid level. These correlations (0.71 for yield, 0.75 for plant height, 0.51 for ear height, and 0.82 for flowering date) were generally higher than those between midparent and F 1 means, but not high enough to accurately predict hybrid performance if selection were based on inbred genotypic means.
Dudley et al. (Sun,) studied this question.