CBGG

In this paper is reviewed some aspects of the research conducted in sub-Saharan Africa in which the genotype main effect plus genotype by environment interaction (GGE) biplot was employed for the analysis and interpretation of the data. GGE biplot has been found quite effective in analyzing genotype × environment interaction, genotype × trait (GT) interaction, interpretation of diallel and line × tester data, and evaluation of the efficiency of testers in hybrid production. Application of GGE biplot to genotype by environment data from several studies has helped to identify outstanding varieties, inbreds and hybrids of early and extra-early maize in terms of yield performance and stability under stress and non-stress environments. The use of GT biplot analysis has resulted in the identification of ear aspect (EASP), plant aspect (PASP), anthesis-silking interval (ASI), and number of ears per plant (EPP) as the most reliable traits for selection for yield under drought, low-N, high-N and well-watered environments. Studies comparing GT with path-coefficient analyses revealed that both methods identified EASP, plant height (PLHT), and ASI as the most important traits directly contributing to yield under drought stress. GT biplot identified EASP, EPP, and Striga damage as the most reliable traits for indirect selection for improved grain yield under Striga infestation. The biplot graphical analysis allowed visual display of the general combining ability (GCA) of the parental inbreds and specific combining ability (SCA) of the hybrids used in Griffings diallel mating design. In addition, information on the best mating partners, identification of proven testers and tester groups, and heterotic groups have been provided graphically. The disadvantages of the GGE biplot include limited number of entries, only two heterotic groups are handled by the method, and only fixed statistical model can be used. More attention needs to be focused on test of hypothesis and QTL analyses.

biplot; genotype; genotype by environment interaction; maize; stability; sub-Saharan Africa