Abstract. In ecological field experiment involving common wheat varieties, several quality parameters were analyzed, which express different aspects of grain quality. Objective of the study was to establish in detail the main relations about the influence of the conditions (location and year) and their interaction with the genotype on each of the parameters, separately. The accepted hypothesis was that the growing conditions have a different strength and direction of effect on each parameter, which should ultimately be reflected in a unique way on the performance of each variety of the studied group. In four locations, which represent a sample of the main grain-producing regions of the country, twenty-four varieties of common winter wheat were investigated. Five indexes of grain quality were analyzed as follows: Sedimentation index (Zeleny); Deformation energy (W); P/L alveograph configuration ratio (P/L); Swelling index (G); Dough stability time (Dstab). All possible aspects of the interaction of genotype (GEN), environment (ENV) as well as the interaction between them (GEN*ENV) were investigated. Statistical approaches and methods that are specialized for this purpose were used. Each of the three main factors – “location”, “year” and “genotype” influenced the variation of the group of varieties through the changes of the conditions, independently and in combination with each other. In this combination of effects expressed as (GEN*ENV) the most essential role was the “location”. The established significant interaction caused an adequate (linear) and inadequate (non-linear) change of the varieties, relative to those of the conditions. For the majority of parameters, this change was mostly linear (PC1=70%), with the exception of the P/L (alveograph configuration ratio), where both effects had parity (PC1≈PC2-4). The environments in the locations during individual seasons had high degree of repeatability (H2=0.75 – 0.94), which allows a high degree of prediction of the values of each single parameter. All parameters were affected to varying degrees by the studied factors and the interaction between them. The influence of the conditions was relatively the strongest on the Dough stability time index (Dstab), and the Swelling index (G) was most closely related to the genetic predisposition of the variety. The effects of the interaction of the genotype with the environments (GEN*ENV) made up about 20-30% of the total variation of three of the parameters, for Deformation energy index (W) the effect reached 40%, and for the Dough stability time index (Dstab) it was only about 13%. The environments during the seasons were the cause of a dynamic change of the correlations between the yield and some of the parameters, in some of the locations studied. Probably, this was directly dependent on the specific combination between the levels of extraction and the level of a given parameter.
