Graphical techniques have become important tools to show
results of maize (
Zea mays
L.) breeding experiments in
current literature. The present study compared different
graphical techniques to determine the best parental lines
and cross combinations for yield and kernel quality traits
in maize breeding experiments. We measured single plant
yield, protein content, oil content, carotenoid content,
oleic acid, and linoleic acid in a 5 × 2 line × tester design.
Genotype + genotype × environment (GE) biplot, principal
component analysis (PCA) biplot, and polar plot were used
to analyze data and compare them with conventional line ×
tester analysis. In the conventional analysis, parents with
high means and positive general combining ability (GCA)
values were A680 and HYA for single plant yield, IHP for
protein content, IHO and HYA for oil content, A680 and Q2
for carotenoid content, IHP for oleic acid content, and A680
for linoleic acid content. The B73 tester exhibited positive
GCA values for most investigated traits. The HYA × B73
combination was the best cross in terms of single plant yield,
protein, and oil contents. Results showed that biplot methods
had both advantages and disadvantages. The PCA biplots
can be used alone while the GGE biplot and polar plots
are both useful for combining ability, heterosis, and gene
action analysis in a line × tester design. Overall, graphical
analysis results were very similar to conventional analysis.
Consequently, it was assumed that the graphical methods
used could be useful to analyze/present data from maize
breeding experiments carried out with a line × tester design.
