Growth and phosphorus nutrition of a Paris-type arbuscular mycorrhizal symbiosis.

•  Paris -type arbuscular mycorrhizas (AM) are reportedly the most common morphological type of AM; however, most research has focused on the Arum -type. Asphodelus fistulosus , a common weed in southern Australia, forms Paris -type AM when colonised by Glomus coronatum . It is often found in sites with low nutrient levels, and may therefore be dependent on its AM associations for growth and phosphorus (P) nutrition. •  A. fistulosus was inoculated with G. coronatum and grown in pots containing a soil/sand mixture with P added to give five soil P concentrations. The plants were grown in a glasshouse and harvested 6 and 9 wk after planting, at which times growth, P nutrition and colonisation were measured. •  At low soil P, A. fistulosus showed very marked positive responses to colonisation both in P uptake and growth; both responses decreased with increasing P supply. Colonisation was not greatly reduced by increasing P supply. •  This study appears to be one of the first detailed investigations of P responses in a Paris -type AM, providing insight into what is reportedly the more common but less well studied morphological type of AM.