Relationships Between Enzyme Marker Loci and Morphological Traits in Two Mass Selected Maize Populations 1

Although enzyme loci have been shownto be associated (either directly or through linkage) with quantitative traits in several specific maize ( Zea mays L.) populations, it is not known whether these associations occur in all maize populations. If they do occur generally in maize, it is not known whether the associations can be exploited for maize improvement. for the purpose of determining whether plants with different enzyme genotypes also had different morphologicacl haracteristics, 20 morphological traits were measured on individual field‐grown plants in two maize populations, one of which was mass selected for prolificacy [NHG(M)PI7] and the other for grain yield [NHG(M)C22]. Genotypes at eight and nine enzyme loci, respectively, were determined for the same individual plants. Discriminant analysis was used to discriminate between enzyme genotypes at a particular locus using as discriminating variables the morphological traits remaining after stepwise selection. if discrimination was achieved,t he associations between genotypes and morphological traits were determined. Discriminant functions were associated with yield, maturity, and leaf variables at the acid phosphatasel ( Acpl ) locus in both populations. Total grain yield, the selection criterion in C‐22, was correlated with the first discriminant function which accounted for 61.1% of the variance in the discriminating variables. In P‐17, the second discriminant function was correlated with yield of the top ear on the mains talk relative to number of ears and plant size. In total, in these particular populations in one specific environment, 15 of the 17 pairs of genotypes or groups of genotypes at a particular locus could be discriminated using morphological traits at a probability level less than 0.05. Information from more populations and environments is necessary before the feasibility of using enzyme loci in plant improvement is known.