The influence of weather conditions on duration of particular vegetation periods and yield of bread winter wheat in Forest-Steppe and Polissia

Purpose. To analyze weather conditions in Forest-Steppe and Polissia and identify their effect on duration of particular vegetation periods and yield of bread winter wheat in these areas. Methods. Field trials were established in 2015-2018 in the zones V. M. Remeslo Myronivka Institute of Wheat of NAAS (Forest-Steppe) and Nosivka Plant Breeding and Experimental Station (Polissia). Sowing, phenological observations, and counting were conducted in accordance with conventional methods and guidelines for bread winter wheat breeding. To analyze hydrothermal regime, there were used data of meteorological observations and normal annual indicators (NAI) for the 1980-2015 from the Agrometeorological Station Myronivka and Nizhyn Meteorological Station. Results. During the years of the research, average annual air temperature in Forest-Steppe exceeded NAI (8.3 °С) by 0.6–1.3 °С, in Polissia it exceeded NAI (7.3 °С) by 0.5–2.1 °С. Annual precipitation in Forest-Steppe ranged from 74 to 101 % of NAI (613 mm), in Polissia did from 82 to 110 % of NAI (649 mm). Under optimal sowing terms (the third decade of September), depending on the year conditions the emergence date was noted within 12 days (2015-16, Forest-Steppe) to 30 days (2017-18, Polissia). Total mean temperature during sowing-emergence varied from 161.9 °С (2015-16 in Polissia) to 253.9 °С (2017-18 in Forest-Steppe). Autumn vegetation in different years continued 22–55 days in both climatic zones, period of winter dormancy did from 85 to112 days in Forest-Steppe and from 92 to 110 days in Polissia; period from spring vegetation resumption to heading was from 85 days in Forest-Steppe to 110 days in Polissia. Duration of interphase period from heading to full ripeness averaged 64 days in both zones. In 2015-16, in Forest-Steppe unlike Polissia all the varieties studied exceeded the standard Podolianka in yield. In 2016-17, winter wheat yield in Forest-Steppe zone was significantly lower as compared to Polissia because of prolonged soil-air drought. In 2017-18, higher yield was observed in Forest-Steppe, as optimal weather conditions in the zone were more favorable than waterlogging in Polissia. Conclusions. The weather conditions in the years of the research reflected the climate instability of Forest-Steppe and Polissia regions of Ukraine. Differentiation of promising varieties of bread winter wheat in duration of particular vegetation periods and yield depending on weather conditions was revealed. Yield reliably depended on the climatic zone, year of the research, and on their interaction. During three years of the research, higher yields were obtained in Polissia area, where weather conditions were more favorable for grain productivity formation.