Effect of Magnum herbicide on productivity and quality of modern fiber flax cultivars

The aim of the research was to evaluate the response of 20 modern cultivars of fiber flax of different maturity groups of domestic and foreign breeding to treatment with the herbicide Magnum, VDG (metsulfuron-methyl, 60 g/kg) and to identify stress­resistant forms for use in breeding programs. Field studies (hole nursery) were carried out in 2021-2023 in the Tver region. Flax crops were treated with herbicide at the recommended consumption rate of 0.01 kg / ha in the "herringbone" phase. The test revealed a decrease in the productivity and quality of flax fiber against a selective background compared to the control without treatment, which in the most sensitive variety ‘Levit 1' (Republic of Belarus) was as follows: plant height - 22.9 %, weight of the technical part of the stem - 41.6 %, fiber weight - 47.1 %, technical length - 28 % and rippleness of the stem - 23.1 %. A decrease in seed productivity under the influence of the herbicide Magnum was found only in early and mid-ripening cultivars. Thus, in the early-ripening cultivar ‘Tomich 2' (Russia) in the variant with herbicide treatment, the number of bolls and seeds per 1 plant compared to the control was lower by 54.9 and 57.7 %, respectively. Late-ripening cultivars ‘S-108', ‘Soyuz' and ‘Krepysh' (Russia) showed high resistance to herbicide stress (over 90 %) by the productivity parameters. According to flax fiber quality, the level of herbicide resistance of the mid-ripening cultivar ‘Surskiy' (Russia) corresponded to the standard - the ‘Atlant' (Russia). The mid-ripening cultivar ‘Grant' (Republic of Belarus) combined resistance to herbicide stress both in terms of flax fiber produc­tivity and its quality. The stress-resistant cultivars that stood out against the selective background exceeded the average varietal values for the analyzed characteristics, which indicates their adaptability to growing conditions.