Homeostasis in terms of the length of the main ear of soft winter wheat varieties in 2021-2023

The results of three-year research (2021–2023) are presented on the evaluation of homeostatic indices based on main spike length in 12 winter wheat varieties of different ecotypes: forest-steppe, steppe, and Western European. Based on the calculation of the mean value (x̄), variation limits (Lim), variance (S²), and the homeostatic index (Hom), considerable variability of the trait was revealed depending on genotype and annual growing conditions. A higher level of homeostatic stability was established in the forest-steppe ecotype variety Zoреpad Bilotserkivskyi (Hom = 423) with minimal variance (0.02). Among the Western European ecotype varieties, Moulan (Hom = 147) and Fidelius (Hom = 146) proved to be more stable. The greatest spike length was recorded in the varieties Acratos (10.5 cm) and Actor (10.0 cm); however, these varieties were characterized by low homeostatic index values and high sensitivity to environmental factors. The data obtained allow for the identification of the most adaptive genotypes for further breeding work. 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.