Differentiation of valuable for breeding sunflower lines by resistance to Phoma rot

Abstract

The purpose of the research is differentiation of valuable for breeding sunflower lines by resistance to Phoma rot. The promising constant sunflower lines were estimated by their resistance to Phoma rot using methods of artificial inoculation in the greenhouse and laboratory conditions. In greenhouse conditions, there were used two methods of artificial inoculation with a fungus Plenodomus lindquistii in the bottom of leaf petiole of a sunflower plant at a stage of the first true leaf pair. Application of the pieces of agar nutrient medium with mycelium, pycnidia and picnospores (unbroken) allowed to identify resistant and mid-resistant sunflower lines (VK 900, L 86 and L 107, L 132). At inoculation with 0.2 ml of a fungus spore suspension (concentration of 1 × 106 spores/ml), five susceptible and one very susceptible sunflower lines (L 2385, L 103, L 136, L 131, L 128, and L 82) were determined. In laboratory conditions, the quick test for estimation of susceptibility to Phoma rot (dose of infection – 12 g) allowed to reveal more than 50 % of plants with healthy root system and two constant sunflower lines L 116 and L 136 with the affection degree of one point. Estimation of susceptibility to Phoma rot infection of the different organs (stem and root system) at artificial inoculation showed a possibility to differentiate sunflower lines by resistance of roots and stems and to select the most promising for the further work in breeding.