New early ripe variety of fiber flax Strizh for the conditions of the North-West of Russia

The purpose of the research is a comprehensive assessment of the main breeding valuable traits and properties of a new fiber flax variety Strizh on the basis of breeding variety testing. The studies were carried out on sod-weakly podzolic well-cultivated soil in the conditions of the North-West of Russia (Pskov region) in 2018-2020. The most favorable hydrothermal conditions of the growing season for the growth and development of fiber flax were in 2019 (HTC = 1.53; Ij = +1.57), unfavorable – in 2018 (HTC = 0.95; Ij = -0.80). The Strizh variety is a high-yielding in flax fiber early-ripening type (the growing season is 69 days) matures 2-3 days earlier than Dobrynya standard variety. The average yield of flax fiber over the years of the research is 18.6 c/ha, which significantly exceeds the standard variety by 2.3 c/ha or 14.1 % (LSD05 - 0.90 c/ha), maximum yield is 20.3 c/ha. In terms of seed yield, it was inferior to the standard (9.9 c/ha) by 1.8 c/ha or 18.2 %. The new variety is highly resistant to lodging (5 points) and fusarium wilt (85 %). It has a very high flax fiber content in the stems (40.0...40.6 %), which is 3.1...4.8 % (abs.) higher than the standard, and its better quality (strength and flexibility). In production conditions, it provided the production of 19.5 c/ha of flax fiber, that is 2.3 c/ha or 13.4 % higher than the standard (LSD05 = 0.96 c/ha). It has the highest yield under contrasting conditions (genetic flexibility) – 19.3 c/ha and higher stress resistance (-2.0). The Strizh variety and the standard are characterized by low variability of fiber flax yield (CV = 9.8-9.6 %), they are also distinguished by high plasticity (bi = 1.12-1.17), which indicates a good responsiveness of these varieties to improved environmental conditions. The Strizh variety has been in the state variety testing since 2021.