MULTI-SCALE EVALUATION OF LAND USE MANAGEMENT SYSTEMS IN THE UPPER MIDWEST
Location: Soil Management Research
Title: Phenotypic structures and breeding value of open-pollinated corn varietal hybrids
Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 29, 2010
Publication Date: November 24, 2010
Citation: Jaradat, A.A., Goldstein, W., Dashiell, K.E. 2010. Phenotypic structures and breeding value of open-pollinated corn varietal hybrids. International Journal of Plant Breeding. 4(1):37-46.
Interpretive Summary: There is some renewed interest in open-pollinated varieties and open-pollinated varietal hybrids of corn, especially among organic and low-input farmers, due to their stable yield and broad adaptation as compared with hybrid corn. In addition, open-pollinated varietal hybrids may have better drought tolerance, prolificacy, superior quality, and nutritious value as livestock feed and human food. We estimated and partitioned total phenotypic variance into its components, quantified population structure, and estimated phenotypic diversity and broad-sense heritability of 35 plant, ear, and kernel traits in 46 open-pollinated varietal hybrids grown under four environments. Large differences were found between varietal hybrids for phenotypic traits (especially reproductive traits), phenotypic diversity indices, and for the frequency of variants for desirable traits. We identified varietal hybrids with large grain-yield potential associated with small variability across environments, along with the phenotypic traits contributing to this large and stable yield. The information on the variability available in these varietal hybrids and their breeding potential is of value for corn breeders in pursuing breeding and selection objectives for organic and low-input farming and for farmers to stabilize yield through increased diversity on the farm.
The growing interest in using open-pollinated varieties (OPVs) and varietal hybrids (OPVhs) of corn (Zea mays L.) especially in breeding programs for organic and low-input farming reflects the value of large plasticity levels available in their plant, ear, and kernel traits. We estimated and partitioned total phenotypic variance into its components, quantified population structure and estimated phenotypic diversity and broad sense heritability (H2) for 35 traits measured on the 46 OPVhs grown under four environments (E). A large portion (68%) of total variation in all phenotypic and yield traits of the 46 OPVhs was partitioned among heterotic groups of their maternal parents (HGs), and was associated with large levels of mean population differentiation (GST; 0.53-0.80) of traits across HGs. Significant levels of variation, whether based on a matrix of phenotypic traits (P1) or grain yield (P2), were found among HGs and among OPVhs(HGs). Most traits were significantly correlated (r=|0.22-0.83|) with grain yield per plant (GY); however, a few traits displayed significant OPVhs(HGs) x E interaction. Average GY across environments was inversely related to its variance; nevertheless, we identified OPVhs with large GY associated with small variance along with the traits contributing to this large and stable GY. Estimates of H2 ranged from 0.35 to 0.85, with decreasing average values for kernel (0.69), ear (0.62), and plant (0.53) traits and a concomitant increasing level of OPVhs(HGs) x E interaction. Pairwise phenotypic distances among OPVhs indicate that most OPVhs(HGs) have different P matrices; and, therefore, will have different breeding potential.