A conceptual method for value determination of the contrast between common winter wheat genotypes in terms of their productivity

One of the most important aspects of any breeding program is to ensure genetic diversity among the studied genotypes. However, the larger it is, the harder it is to cover in breeding point of view. The presence of very different or so-called contrasting genotypes in multienvironmental trials (MET), especially in crops such as common winter wheat, is the cause of obtaining unclear information and the impossibility of determining and ranking the superior genotypes. This affects in a negative aspect even the interaction between the genotype and the environments, which does not make it possible to correctly determine the phenotypic stability. In order to overcome these shortcomings, an attempt was made to construct a conceptual method for empiric determination of the contrast between individual genotypes, which would serve as a corrective in the statistical processing of the data from the METs. In order to investigate the applicability of this methodology, the results for the grain yield of 16 genotypes of common winter wheat in three contrasting growing periods were used. On the basis of the formed concept and the obtained results, an empiric methodology was created and justified for determining a contrast between genotypes according to their productivity in different growing conditions. Its application on real data exhibit that the studied set has a harmonious character and the majority of lines and cultivars do not differ significantly in their productivity compared to the others. Only four genotypes (Dragana, G4, G7 and G11) show higher contrast values, which suggests that the evaluation of their stability should be approached with particular care. The created methodology allows the assessment of stability and adaptability to be adjusted depending on the obtained value contrast, which would enable a more adequate assessment of the phenotypic stability of the yield.