Flax genotypes with horizontal resistance to pasmo (septoria) for breeding purposes

Abstract

Relevance. Flax pasmo currently belongs to the most common diseases in the flax-growing regions of the Russian Federation. In the years of epiphytotics, losses from the disease can increase up to 25–30%. Purposeful breeding work for resistance to pasmo is restrained, first of all, by the absence of highly resistant to the disease of the initial forms of long-lived flax. The purpose of our research was to search for genotypes with horizontal resistance to flax pasmo for use in breeding programs for disease resistance.Methods. The total assessment of the harmfulness of the disease was the criterion «area under the disease development curve», the stability index of each sample was calculated.Results. In the conditions of Tver region (2019–2021) in an infectious nursery on an artificially provocative background to pasmo in the field, the stability of the collection and breeding material of long-lived flax was determined in dynamics. During the years of research, 731 flax genotypes were analyzed, the level of horizontal stability of each genotype was calculated. During the study, 61 genotypes with different levels of protection were identified, characterized by a delayed type of pasmo development. The stability index was 0.26–1.8 cu. The greatest breeding and immunological value is represented by 29 genotypes (L-2815-7-1, L-2808-8-5, L-2633-8-1, 0-15157-6-4, 0-15157-6-14, 0-15157-6-4, 0-13606-8-7, L-2815-7-1, L-3003-6-4, r-311-538-9, r-61-523-9, L-2947-6-3 etc.) in view of the high stability index. Тhe highlighted Selected samples with a horizontal type of stability should be used for flax breeding programs. These samples for two to three years showed a high and average index (0.26–0.6 cu) of stability.