Fig. 1. A dendrogram based on cluster analysis of the relatedness coefficient matrix for Serbian winter wheat cultivars using the Information and Analytical System of Wheat Genetic Resources GRIS 3.0 (Martynov and Dobrotvorskaya 1993 ). In summary, breeding of winter common wheat in Serbia is oriented towards the production of noncarriers of hybrid necrosis genes, however, a certain increase in frequencies of the ne1ne1Ne2Ne2 genotype is observed. This tendency is characteristic of many breeding centers in the world, although it is still difficult to explain.