Influence of irrigation and weather conditions on the duration of interphase periods of winter wheat varieties

The autumn growth and development of plants depend on a complex of external factors: the average daily air temperature, the amount of precipitation, the humidity of the seed layer of the soil, nutrients, light, etc. If winter wheat is sown at a later date, there are risks that the plants will enter the winter not well developed. It is possible to accelerate the passage of interphase periods with the help of irrigation, which is a necessary agrotechnical measure in the Southern Steppe of Ukraine. The purpose of the research is to establish the influence of varietal characteristics, irrigation and weather conditions on the duration of interphase periods of winter wheat in the autumn period on an international scale. Experimental research was carried out during 2020-2021 on southern chernozem, on the basis of the Educational Scientific and Practical Center of the Mykolaiv NAU with two varieties of winter wheat. Field, laboratory and comparative calculation methods were used during the research. The establishment and conduct of experiments were carried out according to the methodology of the research case. Soil moisture was determined by the thermogravimetric method, and phenophases were determined simultaneously throughout the experiment. It was determined that irrigation for 1-2 days reduces the duration of the interphase period of BBCH 00-09; for 3 days – BBCH 10-12; for 11 days – BBCH 13-19; for 5-7 days – BBCH 20-22. In natural conditions (without irrigation), the duration of the interphase periods (from BBCH 00-09 to 20-22) of the growth and development of plants of the studied varieties of winter wheat in 2020 was 93-96 days, which is 23-25 days more than in 2021. In plants of the Ovid variety under conditions of natural moisture (without irrigation), the interphase periods came 1-3 days later than in the Duma Odeska variety, while under irrigation conditions there was no significant difference. The obtained scientific results of the research will contribute to the wider implementation of irrigation, which will ensure the rapid and full growth and development of winter wheat plants in the autumn period, which will further contribute to increasing the yield and gross harvest of grain