BARROW, JR1, INEZ FEDERL, H. CURTIS MONGER2.
1 USDA-ARS Jornada Experimental Range, 2 Dept. Agronomy and Horticulture, New Mexico State University. Las Cruces, NM, 88003. USA.
Seeds of Fourwing saltbush, Atriplex canescens (Pursh) Nutt. are naturally inhabited by septate fungi. Upon germination, fungi colonize the emerging radicle forming a mycorrhizal like association. A. canescens plants were grown in root exclusion chambers with zero phosphorus, 30ppm soluble phosphorus, insoluble rock phosphate or tricalcium phosphate. The roots were separated from insoluble phosphorus sources by a 20 u m screen. Plants grown with insoluble phosphate were colonized with a fungus identified as Aspergillus sp. which penetrated the screen, solubilized phosphorus, enhance biomass and increased phosphorus use efficiency. Plants treated insoluble phosphorus took up only 1/3 as much phosphorus as those treated with soluble phosphorus and had equal shoot and greater root biomass. Fungi aggregated sand particles below the screen by physical entanglement and accretion of an amorphous material, suspected to be polysaccharide. Aggregation was greater in insoluble phosphorus treatments. Septate seedborn fungi in A. canescens function similar to mycorrhizal fungi in accessing phosphorus for seedling establishment and survival and in aggregating and stabilizing sand.