There were three replicates of each fungal treatment and two harvests, requiring a total of six pots per fungus. Four seedlings were transplanted into each pot through holes in the aluminium foil. A small plug of inoculum (approximately 0-2 g agar and fungal colony) was also placed with the seedling roots at planting to ensure maximum success of the inoculation procedure. Uninoculated control seed- lings received an equivalent quantity of agar without mycorrhizal fungi. Pots were placed on benches in an air-cooled glasshouse (air temperatures ranged from 10 ?C to 30 ?C) and soil moisture maintained by watering to weight. Following establishment, seed- lings were thinned to two per pot. Nitrogen (18 0 mg kg-' sand) was added fortnightly as NH4NO3 in solution so that a total of 126-0 mg N kg-1 sand was applied to each pot.