Genotype effects can result in recommendation mistakes in corn (Zea mays) competition trials. The objective was to verify if corn genotypes were well arranged and their consequences to mean comparisons. Six experiments were carried out at the experimental area of the Federal University of Santa Maria with early, medium and late cycle corn genotypes during 2000/2001 grown season. The experimental design was a factorial (genotype in main plots and plant density in sub-plots) in a randomized complete block with three replications. The mathematical model assumptions were adequate in most cases. Genotype arrangements were not adequate for cycle and plant height, increasing experimental errors and reducing statistical power of mean comparisons. Corn genotypes with different cycle and/or plant height should not be compared in the same plant density and trial.
plant population; competition trials; Zea mays
