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Mycorrhizal infection and its consequences were assessed for Agave deserti Engelm., Ferocactus acanthodes (Lem.) Britton & Rose, and Opuntia ficus-indica (L.) Miller. For A. deserti and F. acanthodes in the field, mycorrhizal infection varied from 2 to 11%; the higher infection in May than in March 1991 was probably associated with improved soil water conditions. Using field-collected fungi, mycorrhizal infection for glasshouse-grown A. deserti , F. acanthodes and O. ficus-indica varied from 8 to 64%, with the highest infection occurring for lateral roots of A. deserti . Five months after inoculation, root P was significantly higher (P < 0 01) for inoculated A. deserti and shoot P and Zn were significantly higher (P< 0 02) for inoculated A. deserti and F. acanthodes compared with uninoculated plants. Root hydraulic conductivity (Lp) of lateral roots of A. deserti was 24% higher for inoculated than for noninoculated plants (P < 0 1). The increase in Lp was caused by a higher radial conductivity, which could be due to increased root cell membrane permeability and more hyphal entry points. Dailey net CO2 uptake was 19% higher for inoculated than uninoculated A. deserti . Mycorrhizal infection apparently enhances water and nutrient uptake in dry environments for these three desert succulents.
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