Nitrogen fixation by associative grass - bacteria systems; annual report, 1980

Research has progressed as scheduled. Inoculation of field plots of grasses and grains with Azospirillum failed to consistently increase dry matter yield. A search throughout Florida netted numerous highly active plant species in natural soil-plant systems from which several hundred strains of N-fixing bacteria were isolated and characterized by physiological and morphological traits. Plant roots were microscopically analyzed to detect the mode of bacterial association and infection. Suspension tissue cultures from selected strains were established and used to maintain N-fixing activity for long periods of time. A simple, quick method of screening plant genotypes, evaluating plant bacteria, and studying P-B interactions was developed. Lastly, in addition to the project"s research thrust, significant training took place (e.g., of 25 students from eight countries participating in training programs, four received M.A."s and seven received Ph.D."s).