Biplot analysis of forage combining ability in maize landraces

In Argentina, maize (Zea mays L.) hybrids selected for silage production and local adaptation are not available for most temperate regions where silage maize can be produced. This study sought maize landraces that could be used as germplasm sources to enhance forage yield and quality in warm temperate areas and emphasized eight landraces not previously selected for grain yield. These were crossed in a diallel mating design and the 28 F1 population hybrids, the eight parental populations, and four commercial hybrids were evaluated in four environments in Argentina for combining abilities and to determine heterotic patterns among germplasm sources, using a biplot diallel analysis. Significant midparent heterosis (MPH) was observed for ear yield (EY), stover yield (SY), and whole plant yield (WY). General combining ability (GCA) effects were significant for EY, SY, and WY. Specific combining ability (SCA) effects were not significant for any trait. The graphical representation offered by biplot analysis allowed a rapid and effective overview of GCA and SCA effects of the populations, their performance in crosses, as well as grouping patterns of similar genotypes. Significant variation among checks was observed for EY and SY. On average, commercial hybrids had greater EY, but lower SY, than landraces and population hybrids. Some landrace crosses showed superior or similar WY than commercial checks, indicating the breeding potential of the evaluated germplasm.