Ecological Plasticity and Stability of Spring Bread Wheat Varieties by Yield Level in Agro-Ecological Zones of the Forest-Steppe and Polissia of Ukraine

The weather conditions in the two ecological zones Forest-Steppe and Polissia of Ukraine differed considerably in temperature regime and rainfed environments both during growing season as a whole and during particular phases of plant development. This made it possible to estimate spring bread wheat varieties by the levels of realizing their plant productivity potential. The productivity of spring wheat plants mainly depends on the growing zone (29.2%), hydrothermal vegetation conditions (16.3%), as well as their interaction (27.1%). There have been identified the varieties of spring bread wheat Simkoda myronivs’ka, Struna myronivs’ka, MIP Zlata (UKR), Koksa (POL), Leguan (CZE) with increased yield level that were recommended to be grown in ecological zones Forest-Steppe and Polissia. The calculation of ecological plasticity and stability allowed differentiating the varieties of spring bread wheat in accordance with their responsiveness to variatione of growing conditions as well as with adaptive potential. High plasticity by yield level under growing conditions of the Forest-Steppe and Polissia zones was determined in the varieties: Koksa (POL) (bi = 1.02), Simkoda myronivs’ka (UKR) (bi = 1.02), Granny (AUT) (bi = 1, 03), Heroinia (UKR) (bi = 1.01), Etiud (UKR) (bi = 1.02). These varieties may be characterized by adaptive properties as intensive ones with a pronounced response to the environment, i.e. relatively high grain yields may be resulted from a specific response to more favorable growing conditions. There were identified the most stable varieties for terms of yield in two ecological zones Yasna (POL), Siuita, Panianka, Kharkivs’ka 26, Elehiia myronivs’ka (UKR).