The heritability of tolerance to pathogenic fungi <i>Alternaria dauci</i> and <i>Fusarium oxysporum</i> by carrot hybrids

Relevance. Alternaria dauci, Alternaria radicina and Fusarium oxysporumare wide spread and harmful fungal diseases of carrot (Daucus carota L.) in the Russian Federation and in the world. Total losses of roots from these diseases are 35-70%. Obtaining of new varieties and hybrids resistant to these pathogens is complicated by the fact of polygenic control resistance traits to fungal diseases of Alternaria and Fusarium genus. Interaction of polygenic resistance traits with environmental factors causes the soft character of changing these traits: effects of interactions between alleles and genes are changed, the dominant effect become weaker, additive effect become stronger. So, we can say about of the tolerance to complex pathogens for that case.The goal of our study is to determine the heritability of tolerance to fungal pathogens Alternaria dauci and Fusarium oxysporum by hybrids F1 of carrot.Materials and methods. Materials of studies were 7 basic lines with different types of roots; 7 prospective hybrids F1 and mycelium of Alternaria dauci and Fusarium oxysporum with spores (for inoculation). Methods of studies were: evaluation resistance of lines and hybrids F1 (seedlings, adult plants and roots) at different types of infection backgrounds; dispersion and correlation analysis. Resistance the basic lines of carrot to fungi of Alternaria and Fusarium genus was evaluated step-by-step, using several types of artificial and natural infection backhybrids F1. Tolerant samples were selected and they were used in crossings. F1 – hybrids have been obtained and they have been evaluated at artificial and natural backgrounds.Results: 1. One tolerant male form № 1268 and 6 female forms with weak sensitivity to fungi of Alternaria and Fusarium genus were selected from basic material. They were used in crossings. hybrids F1 have been obtained. 2. Analysis the heritability of carrot resistance to fungal pathogens Alternaria dauci and Fusarium oxysporum identified, that such type of resistance inherited by father’s type. 3. Using tolerant carrot line № 1268 in crossings as the male form and 6 female forms with weak sensitivity to fungal pathogens Alternaria dauci and Fusarium oxysporum increased significantly the percent of tolerant plant in 3 F1 – hybrid population under artificial infection on provocative infection background.