PLANT UPTAKE OF SOLUBLE ORGANIC MOLECULES AS N SOURCE

Summary

Plants take up nitrogen principally in the form of nitrate and ammonium; however, evidence is growing that they can also utilize organic nitrogen in the form of amino acids and soluble proteins. We are conducting research to determine whether wheat grown in soil fertilized with organic N utilizes more organic N directly than wheat grown with inorganic N. We are also testing for differences in uptake of amino acids between pre 1930s varieties and modern varieties of wheat to determine whether this trait has been selected for or against by breeding under high inorganic N input. Preliminary results show both wheat varieties Arco and Madsen take up 14C labeled glycine under sterile conditions. Further experiments to determine the role of microbial competition are underway. Selecting varieties well adapted to competing for organic N could be an important means of maximizing productivity in organic and low input agricultural systems as plants gain more effective access to a wider pool of available nutrients in any given time.