The identification of drought tolerant maize accessions by two-step cluster analysis

Water deficit is one of the main limiting factors leading to maize yield reduction in the temperate zone. Global environmental changes additionally put breeding for drought tolerance in the focus of research programmes. In improving drought tolerance of elite hybrids, the first step is identification of drought tolerance sources within the existing gene bank collections. The complete gene bank collection of the Maize Research Institute, Zemun Polje, Serbia, was field tested under extreme water deficit in Egypt, with the aim of identifying tolerant genotypes. Six quantitative traits and a general estimation of the plant habitus during the growing season were estimated. Genotypes were classified by two-step cluster analysis. In the first phase of data analysis the classification was done with four quantitative and one qualitative trait, genotypes being classified into two clusters. In the second phase when the analysis included the duration of the growing season, genotypes were classified into three clusters. The first phase of data analysis pointed out to 231 drought tolerant genotypes, while the second phase data analysis further added a certain number of early and medium early genotypes, giving a total of 558 accessions. Further work on the selected accessions will be continued for the formation of the core collection and direct use in breeding.