Date of Award
Doctor of Philosophy
Zygote selection in two maize (Zea mays L.) synthetics, BS4 and OhS3, was compared with a modified gamete selection method. Inbreds A619 and A632 were crossed with BS4 and OhS3, respectively, to form the breeding populations (A619/BS4 and A632/OhS3) for the modified gamete selection method. Thirty-one lines derived by the two methods from both synthetics were crossed with three single-cross testers. The testcrosses were evaluated at four locations in 1981 and 1982. The inbreds were also grown as separate experiments at two locations for agronomic evaluation;Nine A619/BS4 and six BS4 lines were significantly greater than A619, the sampler inbred, in testcross grain yield averaged across testers and environments. Of these lines, however, three A619/BS4 lines and five BS4 lines were significantly higher than A619 in grain moisture at harvest. In total, 10 A619/BS4 and 15 BS4 lines were considered superior to A619 in yield for maturity (i.e., superior to A619 in yield and equivalent in moisture or equivalent in yield and significantly lower in moisture). However, of the 10 A619/BS4 and 15 BS4 lines, five A619/BS4 and 13 BS4 lines were higher than A619 in percent stalk lodging in testcrosses. In addition, one A619/BS4 line and eight BS4 lines were significantly lower in grain yield as inbreds per se compared with A619;None of the A632/OhS3 lines and OhS3 lines was significantly greater than A632, the sampler inbred, in testcross grain yield averaged across testers and environments. Seven A632/OhS3 lines and nine OhS3 lines were equivalent to A632 in yield, but all of these lines were significantly higher in grain moisture compared with A632. Twenty A632/OhS3 lines and 13 OhS3 lines were greater than 90 q/ha in testcross yield compared with 97.9 for A632. Of these lines, 5 A632/OhS3 lines were not different from A632 in grain moisture, but all OhS3 lines were significantly greater than A632 in moisture. There was little difference between the two groups in the performance of the lines per se. One A632/OhS3 line and two OhS3 lines were significantly lower in inbred yield compared with A632;The correlation coefficients between inbred traits and hybrid grain yield were low, indicating no useful value of the inbred data in predicting hybrid grain yield.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Richard Duane Muckler
Muckler, Richard Duane, "Modified gamete selection versus zygote selection in two maize (Zea mays L.) synthetics " (1984). Retrospective Theses and Dissertations. 9014.