Yield stability and adaptive potential of winter wheat cultivars under climate variability in the Right-Bank Forest-Steppe of Ukraine

Abstract. Climate variability has become a major constraint to stable winter wheat production in Eastern Europe, making the identification of cultivars with strong adaptive capacity a priority for both breeding and practice. This study aimed to determine how contrasting hydrothermal conditions affect yield formation in winter wheat and to identify cultivars with favorable combinations of productivity, ecological plasticity, and homeostasis in the Right-Bank Forest-Steppe of Ukraine. The research was based on a multiyear field experiment with winter wheat cultivars grown under a uniform agronomic background. Air temperature, precipitation, and the Selyaninov’s hydrothermal coefficient were used to characterize the growing seasons, while cultivar performance was evaluated through yield analysis, ecological plasticity, homeostasis, correlation analysis, and analysis of variance. The results showed a pronounced interannual variation in thermal and moisture regimes, with a general tendency toward warmer vegetation periods and uneven precipitation distribution. These fluctuations created contrasting environments for crop growth and substantially influenced cultivar performance. Yield formation was closely associated with hydrothermal conditions, and reduced moisture availability during critical developmental stages was accompanied by lower productivity, whereas more favorable moisture supply supported improved yield expression. The analysis demonstrated that environmental conditions and genotype × environment interaction played a dominant role in explaining yield variability, while the direct contribution of genotype alone was less pronounced. At the same time, cultivars differed markedly in their adaptive response patterns. Some genotypes displayed an intensive response type and realized their productivity more effectively under improved growing conditions, whereas other genotypes combined moderate productivity with greater stability across contrasting years. A distinct group of cultivars was characterized by high homeostasis, indicating better buffering capacity under climatic stress. Correlation analysis further showed that hydrothermal conditions during the early reproductive period and autumn establishment were especially important for subsequent yield formation, confirming the critical role of weather patterns at these stages in shaping crop performance. Overall, the integrated assessment of yield, ecological plasticity, and homeostasis proved effective for distinguishing cultivars adapted to climate variability and can be used to improve breeding and cultivar selection for unstable hydrothermal environments.