POTENCIAL SIMBIOTICO Y EFECTIVIDAD DE HONGOS MICORRIZO ARBUSCULARES DE TRES SUELOS SOMETIDOS A DIFERENTES USOS

an experiment was conducted under greenhouse conditions to evaluate the mycorrizal symbiotic potential and mycorrizal effectiveness of three soils of colombia exposed to different uses. germinated seeds of leucaena leucocephala were transplanted in a growth substrate consisting of a soil-quartz (1:1 ratio) mixture. the substrate was inoculated with a crude inoculum of glomus aggregatum, a mycorrhizal fungus of known effectiveness. mycorrhizal effectiveness was evaluated by monitoring p pinnule content of the leucaena seedlings at regular intervals of time during the growth period of 49 days. at harvest, shoot dry mass, shoot p content, and mycorrhizal colonization were determined. plant growth and p uptake were significantly higher in plants growing in the substrate inoculated with g. aggregatum than those plants grown in either non-inoculated substrate or substrate inoculated with aliquots of tested soils. mycorrhizal colonization was very high in the g. aggregtaum inoculated-substrate and virtually absent in the other treatments. results suggest that in the tested soils there were a low mycorrhizal effectiveness and/or low content of mycorrizal infective propagules, which was confirmed by the most-probable-number method and mycorrhizal spore counting.