Effects of plot type on detection of quantitative-trait-locus effects in barley (Hordeum vulgare L.)

Hill plots offer advantages in testing large germplasm arrays with limited area and seed. However, the relationship of trait expression between hill vs. row plots remains in question. The development of quantitative-trait-locus (QTL) analysis offers alternative methods of testing hypotheses regarding levels of coincident gene effects in divergent plots. The objective of this study was to compare hill and row plots in terms of QTL detection, number of common QTLs and plot-type-specific QTLs for various characters in barley. Assessments were based on sets of 100 F₁-derived doubled haploid progeny from two environments of hill-plot data and two sets of multiple-environment row-plot data. Common large-effect QTLs for height, heading date, and 1000-kernel weight were detected in both plot types. Fewer QTLs were detected in the hill-plot data, with only one QTL detected for grain yield. There were no hill-plot-specific QTL effects. Hill plots appear to be best suited to highly heritable characters such as height, heading date, and 1000-kernel weight. Evaluation of grain yield is best deferred until larger experimental units can be employed.