Effect of Growth-Stimulating Preparations on a New Fiber Flax Variety, Phoenix

This paper discusses the effectiveness of two plant-growth regulators, Med’Agro and Epin, in fiber flax cultivation. Med’Agro is a new-generation preparation containing a copper–ammonia–carbonate complex. The experiment was conducted in 2019–2021 at the experimental field of the Smolensk Research Institute of Agriculture, Federal Research Center for Bast–Fiber Crops against an optimal mineral background (Azophoska (a nitrogen–phosphorus–potassium fertilizer) 16 : 16 : 16 applied at a rate of 300 kg/ha). The experimental site features a sod–podzolic medium loamy low-humic slightly acidic soil with an elevated phosphorus content and medium potassium content. The subject of this study was a new promising fiber flax variety of Smolensk selection: Phoenix. Flax plants were treated with growth regulators twice: at the herringbone and budding stages. It was found that the fertilizer and growth-stimulating preparations have a positive effect on the formation of structural elements of the fiber flax yield. In plants treated twice with a mixture of Epin and Med’Agro at a concentration of 0.8% against the Azophoska background, 1000-seed weight increased by 39% and number of bolls by 145%. As a result, the flaxseed yield increased to 7.2 c/ha (105% relative to the control). Correlation analysis made it possible to identify a strong relationship between 1000-seed weight and fiber flax yield (r = 0.80). Additional treatment of fiber flax plants with a mixture of growth-stimulating preparations increased the flax straw yield by 114–148%, long fiber yield by 102–181%, and specific long fiber yield by 19–22%. The application of growth-stimulating preparations increased the strength of flax fibers by 10–61% but reduced their flexibility.