Influence of seed sowing rates on height, development and yield of the Russian varieties of oil-type sunflower in the Tashkent region of the Uzbekistan republic

To obtain high yields of good quality of sunflower seeds, it is necessary to strictly observe scientifically justified cultivation technology, which combines techniques accounting both the biological features of the crop and the natural and climatic condi tions of the region. But the role of varietal agricultural technology is also great, which takes into account the properties of a new variety and ensures the fullest realization of its productivity potential under these conditions. Research and development data are very important when introducing crops or varieties into new regions. In this regard, it became necessary to study and scientifically substantiate the optimal seed sowing rates of Russian sunflower varieties in irrigated conditions of the Uzbekistan Republic. The effect of seed sowing rates on the growth, development and yield of Russian oil sunflower varieties was studied in 20202021 at the experimental station of the Tashkent State Agrarian University of Uzbekistan. The objects of the research were promising varieties Irtysh, Skormas (Russia) and the local variety Dilbar (Uzbekistan), which were cultivated at different seed sowing rates, providing a plant population of 40, 50, 60 and 70 thousand plants per ha. As a result of the studies, we found out, according to the complex of economically valuable traits, the best varieties of oil sunflower in the conditions of the Tashkent region are the middle maturing variety Dilbar of the local selection and the ultra-early maturing variety Skormas of the Russian selection, they formed the highest yield in the main crops on irrigation with a seed sowing rate of 50 thousand plant per ha - 4.35 and 4.09 t per ha, respectively. The Russian variety Irtysh is ultra-early maturing, the growing season is 86-88 days, it is less productive and can be considered as promising for repeated crops.