FACTORS INFLUENCING DISEASE RESISTANCE IN HIGH AND LOW TANNIN VICIA-FABA

The in vitro resistance of five white and four coloured-flowered lines and cultivars of Vicia faba to seed and root inoculation with spore s uspensions of the pathogenic soil-borne fungi, Fusarium culmorum and P ythium debaryanum, was investigated under aseptic conditions in the UK . The presence of foliar diseases was also assessed in the field in 19 89/90. White-flowered lines were more susceptible than coloured genoty pes to fungal infection during germination but equally resistant durin g seedling growth. High-tannin containing seed coats had chemical and physical properties which protected seeds against fungal infection dur ing germination. Frequent cracking of the seed coat in a zero-tannin l ine was associated with a greater fungal contamination of seeds. Resis tance to the foliar diseases Uromyces viciae-fabae and Botrytis fabae was not related to flower colour. The results are discussed in relatio n to emergence in white-flowered types.