Lining Tian
Southern Crop Protection and Food Research Center, AAFC

Nitrogen is an essential nutrient for attaining high yields for various crops, especially cereal crops. Shortfalls in available nitrogen in soil are usually provided by the use of industrial fertilizers. Nitrogen fertilizers are costly and are the highest operation cost to grow various crops. Nitrogen fertilizers are based on ammonia, which is largely produced from natural gas. Sharp increase of natural gas price has significantly increased nitrogen fertilizer prices. This has further increased the crop production cost. In addition, nitrogen fertilizer uptake by crops is often low and sometimes as low as one quarter of applied nitrogen fertilizers is actually taken by crops. Unused fertilizers are deposited to soil and underground water systems and cause major environmental pollution problems. Heavy nitrogen fertilizer usage has been a central theme and issue of plant agriculture. Gluconacetobacter diazotrophicus is bacterium freely lives in the intercellular spaces of the sugarcane plant. The bacterium can actively fix atmosphere nitrogen and provides significantly amounts of nitrogen to sugarcane plants. G. diazotrophicus has a wide range of growth conditions, does not form specific structure with plants (like nodules in legume plants), and is not species specific. We have conducted research to introduce G. diazotrophicus into corn varieties grown in Canada. The research showed that G. diazotrophicus can be introduced into a large number of corn varieties. The bacterium can move to other organs including stems and leaves from the roots where the plants were inoculated with the bacterium. This indicates that the bacterium can positively adapt to a new plant species. The bacterial population in colonized plants varied depending on the varieties. Sugar contents stem tissues are positively related to bacterium colonization efficiency. Recently, we also introduced G. diazotrophicus bacterium into sorghum plants. The research is an important step for use of this bacterium for nitrogen fixation in different cereals plants. Achieving nitrogen fixation in cereal crops can significantly reduce crop production cost.