Genetic mapping of quantitative trait loci in maize in stress and nonstress environments .1. Grain yield and yield components

The utility of restriction fragment length polymorphisms (RFLPs) in detecting quantitative trait loci (QTL) in maize (Zea mays L.) populations has been established. Conflicting results have been reported on the ability to consistently detect the same QTL across environments. Grain yield is considered to be highly polygenic and strongly influenced by the environment. QTL mapping studies conducted in contrasting environments might increase our understanding genotype x environment interactions and improve selection response in maize breeding. Our objectives were to compare the QTL for grain yield and yield components detected in two diverse environments in an elite, adapted maize population and to investigate the relationship among the genetic factors controlling these traits. A population of 150 F-2:3 lines was produced from the cross of elite inbreds Mo17 and H99. The lines per se were evaluated for 2 yr at the same location. The first year had relatively average growing conditions, but the second year with cool, wet growing conditions provided a stress environment. Grain yield and yield components were measured on replicated progeny each year. By using a linkage map of 111 loci, QTL determinations were made in the two environments and in the mean of the two environments. About 50% of all QTL detected across environments were detected in both environments. These QTL were consistent in the magnitude of their effects and parental contribution. Determinations of QTL in the mean of the two environments were most informative in that 74% of all QTL and 82% of the QTL detected in each of the individual environments were identified in the mean environment. Most QTL identified regions associated with two or more yield components in a manner consistent with correlations among traits and parents phenotypes.