Pesticides Reduce Symbiotic Efficiency of Nitrogen-Fixing Rhizobia and Host Plants
Pesticides reduce symbiotic efficiency of nitrogen-fixing rhizobia and host plants Jennifer E. Fox*†, Jay Gulledge‡, Erika Engelhaupt§, Matthew E. Burow†¶, and John A. McLachlan†ʈ *Center for Ecology and Evolutionary Biology, University of Oregon, 335 Pacific Hall, Eugene, OR 97403; †Center for Bioenvironmental Research, Environmental Endocrinology Laboratory, Tulane University, 1430 Tulane Avenue, New Orleans, LA 70112-2699; ‡Department of Biology, University of Louisville, Louisville, KY 40292 ; §University of Colorado, Boulder, CO 80309; and ¶Department of Medicine and Surgery, Hematology and Medical Oncology Section, Tulane University Medical School, 1430 Tulane Avenue, New Orleans, LA 70112-2699 Edited by Christopher B. Field, Carnegie Institution of Washington, Stanford, CA, and approved May 8, 2007 (received for review January 8, 2007) Unprecedented agricultural intensification and increased crop by plants, in rotation with non-N-fixing crops (8, 15). The yield will be necessary to feed the burgeoning world population, effectiveness of this strategy relies on maximizing symbiotic N whose global food demand is projected to double in the next 50 fixation (SNF) and plant yield to resupply organic and inorganic years. Although grain production has doubled in the past four N and nutrients to the soil. The vast majority of biologically fixed decades, largely because of the widespread use of synthetic N is attributable to symbioses between leguminous plants (soy- nitrogenous fertilizers, pesticides, and irrigation promoted by the bean, alfalfa, etc.) and species of Rhizobium bacteria; replacing ‘‘Green Revolution,’’ this rate of increased agricultural output is this natural fertilizer source with synthetic N fertilizer would cost unsustainable because of declining crop yields and environmental Ϸ$10 billion annually (16, 17).
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