XVI International Botanical Congess

M. excelsa and M. robusta seedlings were harvested after 12 weeks of growth in the presence and absence of fungal inoculum, recieving 5 different P treatments. Inoculum and P availability increased total biomass and leaf area in M. excelsa in a linear manner, but not significantly so in M. robusta. In both species, leaf area was positively correlated with biomass, 70-80 % of which was contributed by leaves. M. robusta performed 50-60 % less than M. excelsa. None of the seedlings showed arbuscular mycorrhizal infection at the time of harvest. However, cessation of nutrient input into the remaining plants resulted in fungal infection within 12 weeks, suggesting that P availability is not the only limiting factor for arbuscular fungal infection in these plant species, but the net availability of other nutrients as well.