PARENT SESSION
Poster Session #25: Mycorrhizal Fungi and Root Processes.
Tuesday, August 6. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Mycorrhizal colonization varies with season in shrubs of the Mojave desert.

Smith-Longozo, Vickie^*,1, Apple, Martha¹, Cogar, Crystal¹, Wells, Christina², Nowak, Robert¹, ¹ Environmental and Resource Sciences, Reno, Nv² Department of Horticulture, Clemson, SC

ABSTRACT- Does mycorrhizal colonization vary with season in shrubs of the Mojave Desert? To explore this question, we examined roots of two co-dominant Mojave Desert shrubs, Larrea tridentata and Ambrosia dumosa, at monthly intervals from January 2001 until December 2001. Fifty-four randomly selected shrubs per species were located near the Mojave Desert FACE (Free-Air CO₂ Enrichment) facility. Nine plants per species were randomly assigned to one of six groups and one group was sampled per month. We collected roots by excavating 25 cm from the bases of L. tridentata and 12.5 cm from the bases of A. dumosa (generally a smaller species). We stained the roots with Trypan Blue and quantified the percentage of mycorrhizal colonization via the line intercept method. Percent colonization varied with season. In L. tridentata, colonization was highest in winter (25%), dropped to a low of (5%) in April, and increased to (18%) by May. In A. dumosa, colonization was the highest in winter (37%), dropped to a low of (9%) in April and increased to (22%) by May. Changes in colonization may reflect soil moisture and phenological events such as flowering and fruiting that influence phosphorus demand.

KEY WORDS: Mycorryzal Colonization, Mojave Desert, Larrea tridenta, Ambrosia dumosa