MOLECULAR-MARKER-MEDIATED CHARACTERIZATION OF FAVORABLE EXOTIC ALLELES AT QUANTITATIVE TRAIT LOCI IN MAIZE

Exotic maize (Zea mays L.) germplasm, shown to be useful for developing improved temperate cultivars, has remained little used partly because of many inherent shortcomings. Five Fz populations, developed from South American and U.S, germplasm, were used to detect favorable factors of exotic origin at quantitative trait loci (QTL) with isozymes and RFLPs. A number of traits of agronomic importance, including grain yield, were measured on Pt individuals and/or F-3 families grown in several environments. Many QTLs, mostly with small effects, were identified. Major QTLs for grain yield and number of ears per plant were located on chromosomes 3 and 6. Stability of QTLs across environments was high. Favorable alleles of exotic origin were found at QTLs for several traits including grain yield and number of ears per plant. Most of these alleles also showed undesirable effects on other traits, however. Nevertheless, the superiority of exotic alleles over adapted alleles was demonstrated clearly al a few QTLs, reaffirming the usefulness of exotic germplasm for temperate maize breeding.