Pathogenicity of Pythium spp. to lucerne seedlings and relationships between seed weight, seedling vigour, and infection by Pythium

摘要

Abstract The pathogenicity of Pythium spp. to ?Wairau? lucerne (Medicago sativa L. cv. Wairau) was demonstrated under glasshouse conditions in a steamed potting mix soil and in two cultivated field soils. Positive relationships were demonstrated between seed weight and seedling growth, and between seed weight and resistance to attack by Pythium spp. in the three soils. A curvilinear relationship existed between propagule density of Pythium spp. and the number of healthy seedlings with little, or no, decrease in seedling numbers at densities greater than 900 propagules per g ovendried soil.