Partial and adult-plant-resistence to powdery mildew in winter barley cultivars

Ross-White, Catherine Mary (1988) Partial and adult-plant-resistence to powdery mildew in winter barley cultivars. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

Partial and adult-plant-resistance was studied using the host-pathogen interaction between barley (Hordeum vulgare L.ssp. vulgare) and powdery mildew (Erysiphe graminis DC f.sp.hordei Marchal). Winter barely cultivars Sonja, Igri, Gerbel, Athene, Halcyon and Maris Otter were inoculated in the laboratory and glasshouse with two races of powdery mildew. The typical `partial resistance' characters; latent period, infection efficiency and sporulation capacity were assessed. The process of infection was also followed, up to 72 hours after inoculation. The characters which distinguished the greater adult-plant-resistance in cultivars Athene and Sonja were sporulation capacity, size of colony and hypersensitivity to infection and in cultivar Athene, the length of latent period. Cultivars Sonja, Igri, Gerbel and Athene were crossed in a diallel and the F1 and F2 progeny were inoculated with mildew. The characters' sporulation capacity, size of colony and hypersensitivity appeared to be additively inherited. The differentially longer latent period in cultivar Athene had a `major-gene' pattern of expression. In two seasons, small field plots of the cultivars were inoculated with mildew and disease progress was followed. Resistance in the cultivars in the laboratory, glasshouse and field was correlated. A comparison of the infection cycle was made using leaves in detached leaf culture and leaves still attached to the plants. A range of concentrations of benzimidazole in the agar medium of the detached leaf culture was used. Resistance to infection was increased in the detached leaves and with increasing concentration of benzimidazole. (DX86652)

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