This article describes a method for processing the results of environmental tests, which allows not only to compare varieties by their average yield, but also to determine their response to changing conditions, assess their potential and select the best varieties for their cultivation in terms of environmental plasticity. The proposed method will make it possible to evaluate cotton varieties by stability in response to changes in cultivation conditions, an assessment of their potential capabilities and selection by their ecological stability (plasticity) in various regions of the Republic of Uzbekistan. The regression coefficients, characterizing the reaction of varieties to changes in the level of yield, turned out to be different, if there is a full correspondence of the yield of a variety to changes in test conditions, the regression coefficient is 1.00. Condition indices varied from point to point by 0.5-4.7 centners / ha. Exactly the same variability is observed in cultivar C -6550, the regression coefficient of this cultivar is 0.9. The yield of “the Khamkor” cotton variety, despite significant fluctuations in the test points, on average changed by 1.3 (bi = 1.3). The yield of the cotton variety UzFA-707 in the test points changed on average by 1.1 (bi = 1.1). It was revealed that the cotton variety C-6545 was more stable in comparison with other studied varieties. Although the yield of this cotton variety is neither maximum nor minimum, it gives a more stable yield.