FEATURES OF THE DURATION INHERITANCE OF THE VEGETATION PERIOD OF HYBRIDS F3-F4 OF SOYBEAN (VEGETABLE) UNDER DIFFERENT GROWING CONDITIONS

Abstract

The article presents the results of a study on the inheritance pattern of the vegetation period duration in hybrid combinations of vegetable soybean (Glycine max L. Merr.) in the F₃-F₄ generations. The aim of the research was to identify forms with various lengths of the period from emergence to full maturity among the studied hybrid combinations of vegetable soybean and to determine the inheritance characteristics of this trait in the F₃-F₄ generations. Methods: the field method was used to record phenological growth stages; the weighing and measuring method – for yield accounting; the laboratory method – for determining yield structure; and statistical and mathematical methods – for conducting analysis of variance and statistical processing of the data to assess the reliability of the obtained results. Various types of dominance were observed, including heterosis (overdominance), partial positive dominance, and negative heterosis (depression). Overdominance in the duration of the vegetation period was recorded in the combinations Karikachi × Fora, Sac × IU031301, L 362-2-13 × Fiskeby V, and Fiskeby V × IU031301. Comparison of variability ranges in F₃ and F₄ showed a narrowing of the variation in F₄ (from 15.2–37.1 to 12.3–24.1 days), indicating the influence of stabilizing selection and agroecological factors. Most hybrid populations in the F₃-F₄ generations were early-maturing (90-105 days), with exceptions such as Sac × IU031301 (ultra-early, 89 days) and Karikachi × Fora (medium-maturing, 113–116 days). The hybrid material under irrigation had a slightly narrower range of vegetation period duration (90-112 days) compared to rainfed conditions (87–109 days). The genotypic variability coefficient (Vg %) under irrigation was 21.8–24.1%, indicating a high breeding potential of the studied lines. The findings confirm the effectiveness of selection in early generations and the feasibility of using heterotic combinations in the development of early-maturing, irrigationadapted vegetable soybean varieties. The study confirmed that in most F₄ hybrid populations, the coefficient of variation for vegetation period duration was lower compared to F₃, indicating reduced selection efficiency for this trait in later generations. The reduction in variability is attributed to the action of stabilizing selection toward betteradapted phenotypes, as well as possible unintended artificial negative selection during harvesting in the phase of mass maturity. Most of the hybrid populations examined in the F₃-F₄ generations were early-maturing, with a vegetation period of 90–105 days. The Sac × IU031301 combination stood out for its ultra-early maturity (89 days) under rainfed conditions, while the Karikachi × Fora combination showed medium maturity – 113 days in non-irrigated and 116 days under irrigation.