XVI International Botanical Congess

A set of M. excelsa and M. robusta seedlings were harvested after 12 weeks of growth under five different p levels in the presence and absence of fungal inoculum. The treatments increased biomass and leaf area in M. excelsa in a linear manner. This was not significant in M. robusta. About 70-80% of the biomass was contributed by leaves. Biomass was positively correlated with leaf area in both species. M. robusta performed 60% less than M. excelsa. None of the seedlings showed any mycorrhizal infection, although cessation of nutrient input into the remaining plants resulted in infection within 12 weeks. Results indicate that P availability is not the only limiting factor for arbuscular fungal infection, but she net availability of other nutrients as well.