Pesticides reduce symbiotic efficiency of nitrogen-fixing rhizobia and host plants

Fox, J. E. and Gulledge, J. and Engelhaupt, E. and et al, . (2007) Pesticides reduce symbiotic efficiency of nitrogen-fixing rhizobia and host plants. Proceedings of the National Academy of Sciences of the United States of America, 104 (24). pp. 10282-10287.

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Unprecedented agricultural intensification and increased crop yield will be necessary to feed the burgeoning world population, whose global food demand is projected to double in the next 50 years. Although grain production has doubled in the past four decades, largely because of the widespread use of synthetic nitrogenous fertilizers, pesticides, and irrigation promoted by the "Green Revolution," this rate of increased agricultural output is unsustainable because of declining crop yields and environmental impacts of modern agricultural practices. The last 20 years have seen diminishing returns in crop yield in response to increased application of fertilizers, which cannot be completely explained by current ecological models. A common strategy to reduce dependence on nitrogenous fertilizers is the production of leguminous crops, which fix atmospheric nitrogen via symbiosis with nitrogen-fixing rhizobia bacteria, in rotation with nonleguminous crops. Here we show previously undescribed in vivo evidence that a subset of organochlorine pesticides, agrichemicals, and environmental contaminants induces a symbiotic phenotype of inhibited or delayed recruitment of rhizobia bacteria to host plant roots, fewer root nodules produced, lower rates of nitrogenase activity, and a reduction in overall plant yield at time of harvest. The environmental consequences of synthetic chemicals compromising symbiotic nitrogen fixation are increased dependence on synthetic nitrogenous fertilizer, reduced soil fertility, and unsustainable long-term crop yields.

Item Type: Article
Additional Information: SNNigam Collection
Uncontrolled Keywords: Legume, Nitrogen fixation, Symbiosis, Sinorhizobium meliloti
Author Affiliation: Center for Ecology and Evolutionary Biology, University of Oregon, USA.
Subjects: Plant Protection
Crop Improvement
Divisions: Chickpea
Common Bean
Depositing User: Mr Arbind Seth
Date Deposited: 03 Apr 2013 10:20
Last Modified: 03 Apr 2013 10:20
Official URL:

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