Biological nitrogen fixation (BNF) is the biological process by which nitrogen (N2) in the atmosphere is converted to ammonia by an enzyme called nitrogenase. The screening of plant genotypes for their enhanced ability to acquire nitrogen by BNF can reduce the use of expensive nitrogen fertilizers in several important crops like sugarcane, rice, wheat and corn. It can greatly benefit particularly the poor farmers of developing countries.
In a recent study aimed to quantify the symbiotic biological nitrogen fixing activity of a range of commercial corn cultivars, Montanez et al. (2009) demonstrated that corn cultivars obtain significant nitrogen from BNF, the level of which varied with corn cultivar and nitrogen fertilization level. The study showed that some cultivars were more sensitive than others to nitrogen application and that 15N isotope dilution method is a useful tool to screen and select corn cultivars with any potential BNF.