Ecological plasticity and stability of promising lines of spring wheat (Triticum aestivum L.) in terms of yield

Purpose. To analyze lines of competitive testing of soft spring wheat in terms of ecological plasticity and stability using statistical methods of analysis and identify lines with high stability of grain yield. Methods. The studies were carried out during 2018–2020, on the basis of the V. M. Remeslo Myronivka Institute of Wheat NAAS of Ukraine. When considering the results obtained, generally accepted methods of genetic and statistical analysis were used. Results. Evaluation of breeding material in different years makes it possible to obtain information about the characteristics of the reaction of genotypes to changes in environmental conditions. As a result of the studies, it was found that the lines Lutescens 14-32 (bi = 0.59), Erythrospermum 15-32 (bi = 0.44), Lutescens 14-47 (bi = 0.22) were of high plasticity. Calculations of ecological stability indicate that lines are considered stable, the variance of stability is zero or close to zero. From a practical point of view, lines with a combined manifestation of high ecological plasticity and stability are considered valuable. This was the line Erythro­spermum 15-32 (bi = 0.44; S2di = 0.01) that indicates its low reaction rate and the ability to provide a consistently high level of yield under any growing conditions. The most valuable are the genotypes that combine a low level of the coefficient of variation, high homeostaticity and bree­ding value, which include the lines Erythrospermum 15-32 (Hom = 206.42, Sc = 4.11), Lutescens 14-47 (Hom = 98.41, Sc = 3.91), Erythrospermum 17-08 (Hom = 78.57, Sc = 3.76), Erythrospermum 14-65 (Hom = 54.84, Sc = 3.75), Lutescens 14-32 (Hom = 54.60, Sc = 4.17), Lutescens 14-13 (Hom = 35.60, Sc = 3.78), Lutescens 14-48 (Hom = 46.66, Sc = 3.58). Conclusions. The evaluation of breeding material is of great importance when creating new high-performance varieties with adaptive potential. The method for assessing ecological plasticity and variants of its stability made it possible to differentiate wheat lines of soft spring competitive testing by their response to changes in gro­wing conditions. For a more optimal selection of breeding material in terms of ecological plasticity and stability, breeding programs should take into account ranked estimates of genotypes