AN ASSESMENT OF EARLY MATURITY OF WINTER WHEAT GERMPLASM MATERIAL OF IWWYT-IR IN THE SEMI-DRY CONDITIONS OF UZBEKISTAN

The article presents research results on the duration of the vegetation and interphase periods of winter wheat germplasm accessions of the 21th, 22th 23th IWWYT-IR (International winter wheat yield trial) for irrigated zones during three consecutive growing seasons from 2018-2020 in the conditions of the Jizzakh region of Uzbekistan. The experimental work was carried out at the Gallaaral Experimental Station of the Grain and Leguminous Research Institute. Field trials were conducted in the evaluation nursery of the starting materials. The samples were sown on plots with a counting area of 10 m2, with two-fold replication. Weather conditions differed sharply during the period of plant growth in April-May. Rainfall amounts in April was 21.9 mm, 172.6 and 91.5 respectivelyfor three consecutive years. Also, the average daily temperature in this month was 13.9°С, 14.1°С and 9.40°С. When assessing the vegetation period from germination to full heading in 2018 season, 40% of the analyzed samples turned out to be relatively early maturing, while in 2019 only 7.5%, and in 2020, 32%. The findings and comparative analysis allowed toassess in detail an investigated wheat germplasm accessions and to select from them donors for further breeding work. The influence of changing weather conditions on the duration of the germination-heading interphase period was determined. It was found that an increase in precipitation in the period from earing to heading slows down the growth of wheat plants.