Formation of Vesicular-Arbuscular Mycorrhizae in Atriplex Gardneri (Chenopodiaceae): Seasonal Response in a Cold Desert

Arbuscules and total VA mycorrhizal colonization in Atriplex gardneri were observed during the spring and summer of 1982. Arbuscules were observed in April (25% of secondary and tertiary root length intercepts) but were not found in June. Total VA mycorrhizal colonization was 78% of fine root length intercepts in April, 28% in June, and 3% by July. The phenology of the fungus was correlated with that of the plant; rainfall and temperature dictated periods of active growth, nutrient uptake, and senescence in the symbionts.