Original article | Helia 2023, Vol. 46(78) 61-75
Kristina Levitskaya Anatoliy Soroka Viktor Lyakh
pp. 61 - 75
Published online: June 01, 2023 | Number of Views: 26 | Number of Download: 42
Abstract
The foliar fungal disease Septoria leaf spot is economically important for sunflowers. It develops most intensively during the wet and warm season. However the genetic nature of sunflower resistance to Septoria leaf spot is still not clear. The purpose of our work was to identify some inheritance patterns of sunflower resistance to this disease based on the assessment of lines and hybrids of the first and second generations. The studied material was sown in 2020 and 2021 and subsequently grown on a stationary artificial infectious plot enriched with Septoria helianthi pathogen. The frequency of infection and the severity of infection of each sample were taken into account. The two-factor variance analysis revealed a significant influence of genotype on the frequency of infection in six sunflower lines and confirmed the effect of individuality of the response of individual genotypes to disease damage. It was shown that about 65 % of the total variation of the trait is due to the genetic nature of the line and only a little more than 20 % and about 11 % – to the influence of the environment and the “genotype × environment” interaction respectively. Based on disease damage data in 2020 and 2021 the lines were classified as susceptible moderately susceptible moderately resistant and resistant. Differentiation of lines according to sensitivity to Septoria leaf spot made it possible to obtain hybrids with different manifestations of the trait in their parents. The nature of inheritance of infection frequency in F 1 sunflower hybrids was determined by the degree of dominance. As a result it was revealed intermediate inheritance as well as positive and negative overdominance of the trait. The severity of infection by S. helianthi pathogen in F 1 hybrids was inherited according to the type of parental form with greater resistance to the disease. F 2 populations were found to inherit infection frequency from the more resistant parent showing a proportion of infected plants similar to that of the more resistant line from a given cross combination. It has been shown that the frequency of infection of the F 2 population with Septoria leaf spot can be affected by the severity of infection of F 1 plant with the pathogen S. helianthi.
Keywords: frequency of infection; inheritance pattern; lines, F1 and F2 hybrids; Septoria leaf spot; severity of infection; sunflower
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