Rhizobial Ecology of the Woody Legume Mesquite (Prosopis glandulosa) in the Sonoran Desert.
Soil samples were collected from the surface (0 to 0.6 m) and phreatic (3.9 to 4.5 m) root systems of a Prosopis glandulosa woodland in the Sonoran Desert of southern California. P. glandulosa seedlings were inoculated with these soils, and rhizobia were isolated from nodules. The phreatic soil, characterized by constant moisture and temperature but low nutrient availability, favored slow-growing (SG) isolates as nodule occupants (85%). SG isolates from the surface and phreatic soil were distinct based on differences in colony morphology. Isolates from the surface soil, characterized by high nutrient availability and widely fluctuating water content and temperature, were equally represented by fast-growing and SG rhizobia. Most SG isolates (83%) had nodule relative efficiencies of <0.80, whereas 54% of the fast-growing isolates had relative efficiency values of >0.80.
Jenkins
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Dry Lands Research Institute and Department of Soil and Environmental Sciences, University of California, Riverside, California 92521, and Biology Department and Systems Ecology Research Group, San Diego State University, San Diego, California 92182.
Virginia
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Jarrell
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