Homeostasis in terms of the number of grains in the main ear of soft winter wheat varieties in 2021-2023.

The results of evaluating the adaptive potential and homeostatic stability of modern winter wheat varieties of different ecotypes are presented, based on the number of grains per main spike. The study was conducted during 2021–2023 among varieties of the forest-steppe, steppe, and Western European ecotypes. It was established that the highest homeostatic index (Hom) was characteristic of the forest-steppe ecotype variety Kvitka Poliv (2472) and the Western European breeding genotype Fidelius (1073). Considerable variability in variance (S²) and in the range of grain number limits was revealed depending on genotype and annual growing conditions. The highest main spike productivity was demonstrated by the Western European ecotype varieties Acratos and Fidelius, with mean values of 50.9 and 50.1 grains, respectively. The findings allow for the identification of the most stable genotypes for further breeding work aimed at developing new source material of soft winter wheat (Triticum aestivum L.). Homeostatic ability (Hom) was calculated according to V. V. Khangildyn and M. A. Lytvynenko (1981): Hom = x² / S, where: Hom – homeostatic ability; x² – the mean value of the studied trait squared; S – standard deviation.