EVALUATION OF POPULATIONS FOR THEIR POTENTIAL TO IMPROVE 3 MAIZE HYBRIDS

Identification of sources of favorable alleles to improve existing hyb rids is one of the most important problems facing a maize (Zea mays L. ) breeder. Previous work has demonstrated the effectiveness of a proce dure developed by Dudley for identifying populations containing favora ble alleles not present in an elite hybrid. However, previously report ed work involved at most two elite hybrids. The objective of this stud y was to evaluate the potential of 20 improved populations to improve the three hybrids made from three inbreds in commercial use. Each of t he populations was crossed to LH195, LH212, and LH216. The population x inbred crosses, the three hybrids among the inbreds, and the three i nbreds were evaluated in seven U.S. midwestern environments in 1993 an d four in 1994. Traits measured were grain yield, grain moisture, plan t height, ear height, and concentration of protein, oil, and starch in the grain. For grain yield, 15 of the 20 populations had significant estimates of dominant favorable alleles not present in the highest yie lding target hybrid (LH195 x LH212). None of the populations showed po tential for reducing ear height. However, seven populations had more f avorable recessive alleles than unfavorable dominants for plant height when LH195 x LH212 was the target hybrid. None of the populations tes ted appeared to have potential for increasing starch concentration in any of the target hybrids. Eight populations showed potential for incr easing protein concentration in all three target hybrids. Assumptions required to identify parents were not met for grain moisture, oil conc entration, and stalk and root lodging.