Submitted to: Plant Roots The Hidden Half
Publication Type: Book / Chapter
Publication Acceptance Date: March 18, 1996
Publication Date: N/A
Technical Abstract: Legume importance in agricultural systems will continue to expand. They replenish and stabilize soils, thus reducing erosion by wind and water. Nitrogen fixed by legume root nodules helps to reduce costly inputs by encouraging reduced application of fertilizer nitrogen to subsequent crops. Nitrogen derived from biological nitrogen fixation can contribute up to 70% %of nitrogen required for a non fixing species grown in rotations. Since nitrogen fertilizer production requires large inputs of nonrenewable resources, prices in the future will undoubtedly rise. Expansion of the use of legumes in cropping systems may buffer against potentially unsettling and limited energy supply. Fixed nitrogen from legumes appears to be less susceptible to leaching and may be useful in reducing groundwater contamination by nitrate fertilizers. Legume root nodules are model systems for studying genes important for nitrogen assimilation. The genes encoding the primary enzymes involved in ammonia assimilation have been isolated from legume species. At least 50 plant genes are involved in the development of an effective root nodule. Root nodule symbiosis will be improved through both traditional plant breeding and new molecular approaches. Improvements in transformation and transgenic technology will result in legumes having improved nitrogen acquisition and assimilation traits.