The effect of the level of arbuscular mycorrhizal fungi (AMF) colonisation on the growth of Pterocarpus angolensis was studied. Mycorrhizal infected seedlings, showing either good or poor growth, under the same environmental conditions (temperature, humidity, light level) were analyzed for above and below ground biomass and N and P concentration. The grouping was based on the number of leaves and seedling size. All plants had AMF infection, with poor growth plants having a 75% infection and good growth plants 45%. The highly infected poor growth plants had fewer leaves, smaller total leaf area and total plant mass. The below ground plant component N and P concentration of good growth plants was higher than in poor growth plants. There was however no difference in N and P concentrations of above ground components between the two groups. No nodules were recorded for good growth plants while plants in the poor growth group had nodules. There was no difference in the specific leaf mass and shoot:root ratio of the two groups, although the leaf area ratio was higher in good growth plants. The high AMF infection had a negative effect on the growth and development of plants. This study highlighted the presence of AMF in nursery grown Pterocarpus angolensis and the host benefits from various colonisation levels. A long-term field trial is needed to study the effects of different AMF colonization levels on tree vigour under different environmental conditions.
Key Words: Pterocarpus angolensis; Arbuscular mycorrhizae; Nitrogen; Phosphate; Growth
Southern African Forestry Journal Issue 202 2004: 13-20