Root exudation from Leucaena leucocephala in relation to mycorrhizal colonization.

Lower amounts of root eduxates (13 mg/g dry root) emerged from leucaena plants inoculated with the mycorrhizal fungus, Glomus fasciculatum, than uninoculated plants (21 mg/g dry root). Mycorrhizal plants exuded less K(+), Pi and sugars (mainly glucose) but more protein, nitrogen, phenolics and gibberellins than uninoculated plants. Glycine, alanine, cysteine, arginine, tryptophan and valine occurred only in the root exudates of the former. Uninoculated plants exuded more of a root-elongation inhibitory substance than the uninoculated ones.