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New research may reduce need for nitrogen fertilizers


March 31, 2008
By Fruit & Vegetable

Topics

Research published recently in the
journal Nature reveals how scientists at the John Innes Centre (JIC) in
England and Washington State University have managed to trigger
nodulation in legumes, a key element of the nitrogen fixing process,
without the bacteria normally necessary.

pea_nodules_nitrogen
whiteclover_nitrogen

Research published recently in the journal Nature reveals how scientists at the John Innes Centre (JIC) in England and Washington State University have managed to trigger nodulation in legumes, a key element of the nitrogen fixing process, without the bacteria normally necessary.
This discovery is an important step towards transferring nodulation, and possibly nitrogen fixation, to non-legume crops, a discovery that could reduce the need for inorganic fertilizers.
The researchers used a key gene that legumes require to establish an interaction with the nitrogen-fixing bacteria and trigger the growth of root nodules, even in the absence of
the bacteria.
The fixation of nitrogen by some plants is critical to maintaining the health of soil as it converts the inert atmospheric form of nitrogen into compounds usable by plants. Legumes, as used in this study, are an important group of plants as they have the ability to fix nitrogen – which they owe to a symbiotic relationship with nitrogen-fixing bacteria in root nodules. Scientists have been working to understand the symbiosis between legumes and rhizobial bacteria, with the hope that one day they can transfer this trait to crop plants, the majority of which cannot fix nitrogen.
Intensive crop agriculture depends heavily on inorganic fertilizers that are often used to provide nutrients particularly nitrogen that are critical for plant growth. The production of nitrogen fertilizers requires a large amount of energy and is estimated to constitute approximately 50 per cent of the fossil fuel usage of the modern agricultural process. Inorganic fertilizers also cause environmental problems associated with leeching into our water systems.
“We now have a good understanding of the processes required to activate nodule development,” said Dr. Giles Oldroyd, research leader at JIC. “The nodule is an essential component of this nitrogen fixing interaction as it provides the conditions required for the bacteria. Nodules are normally only formed when the plant perceives the presence of the bacteria. The fact that we can induce the formation of nodules in the plant in the absence of the bacteria is an important first step in transferring this process to non-legumes. However, we still have a lot of work before we can generate nodulation in non-legumes.”¶

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