Genotype x Environment Effects on The Productivity Traits of Common Wheat (Triticum aestivum L.) II. Analysis of Genotype Reaction

Abstract

Situation and purpose: Twenty-seven genotypes were investigated, including four standard cultivars. The aim was to identify the most stable ones among them with regard to productivity under the conditions of both north and south Bulgaria, and to clarify the behavior of the cultivar with regard to grain yield according to the expression of its productivity components. Methods: To achieve the above aim, various statistical methods and approaches were applied to investigate the correlations of the traits, their variation and effect on grain yield. A method for spatial visualization of the cultivar’s behavior was used according to each of the traits depending on the environment of the respective investigated location over a three-year period. An Integral Breeding Assessment was made attempting to explain in detail the effect of the traits on grain yield (its level and stability). Key results: Each cultivar demonstrated unique behavior with regard to productivity (traits) and to grain yield itself. Their interaction with the environment was significant although there was no direct effect of the year on any of the traits. The year conditions, however, affected the expression of the traits through their interaction with the genotype, which was significant at the highest statistical level. The interactions between the productivity traits and the environment are complex and non-linear which makes the objective evaluation of the cultivar difficult. Conclusions: The traits varied by degree and direction which caused variation in the interactions both among themselves and with regard to yield. A correct evaluation of the plasticity and stability in relation to productivity can be made by applying an Integral Breeding Assessment (IBA) for each cultivar. The used model cultivars (Aglika, Sadovo 1 and Pryaspa) proved yet again that they have been correctly chosen as criterion for enhancing productivity and its stability