Enhancing Nitrogen Use Efficiency in Corn through Introgression of Low N Tolerance from Eastern Gamagrass.

U.S. corn growers apply extremely high rates of nitrogen fertilizer to boost grain yield. This is a key contributor to non-point source water pollution in the Mississippi River drainage system. This project utilizes natural genetic resources and conventional plant breeding techniques to achieve a non-GMO, sustainable agriculture approach to help alleviate this serious environmental problem. The objective is to select and develop hybrid corn that will maintain high yields when grown under reduced nitrogen levels. Reduction in nitrogen applications to corn will in turn help alleviate water pollution, the growing dead zone in the Gulf of Mexico, and nitrous oxide emissions from fertilizer that are a significant contributor to global warming.
Corn lines introgressed with genes from Eastern gamagrass (Tripsacum dactyloides L.) are being evaluated in field experiments to identify low nitrogen tolerant lines. Plants are being grown at three nitrogen levels in a split plot design. The synthetic nitrogen rates were 100 lbs N/ac and 200 lbs N/ac. The third rate was 50 lbs organic N/ac. Analysis of an extensive data set on leaf nitrogen, grain yield, plant height, ear number, 100 kernel weight, grain protein, and other relevant plant parameters identifies the most promising nitrogen use efficient lines to move forward in a breeding program. The first year's field test identified gamagrass-introgressed genotypes with up to 25% greater leaf chlorophyll. This translates to 37.5% increase in grain yield. Initial results indicate good feasibility for developing hybrid corn with reduced fertilizer requirements that could in turn help achieve the Mississippi River/Gulf of Mexico Task Force goal of 30% reduction in N runoff by 2015.