The root morphology of some legume spp. in the south-western Cape and the relationship of vesicular-arbuscular mycorrhizas with dry mass and phosphorus content of Acacia saligna seedlings

Abstract

The root systems of Acacia saligna (Labill.) Wendl. have more extensive laterals than those examples of the Fabaceae indigenous to the Cape. Aspalathus flexuosa Thunb. and Rafnia angulata Thunb. had lateral roots infected with vesicular-arbuscular (VA) mycorrhizal fungi whereas those of Aspalathus albens L. were non-mycorrhizal. VA mycorrhizal fungi were found in the roots of seedlings of A. saligna. Chlamydospores of the genus Glomus and three types of Gigaspora auxiliary cells were identified. VA mycorrhizal colonization was correlated with the dry mass and phosphorus content of A. saligna seedlings. Seedling dry mass, phosphorus content, nodule production and VA mycorrhizal colonization decreased with increased sowing density. The more extensive root system and abundance of root nodules and VA mycorrhizas apparently contribute to the success of A. saligna as an invasive weed of the fynbos vegetation.