NITROGEN FIXATION BY ASSOCIATIVE GRASS - BACTERIA SYSTEMS

EVALUATION CONDUCTED ONSITE AND USING PREVIOUS EVALUATIVE DOCUMENTS; NOTES THAT THE UNIV OF FLORIDA HAS MADE A SYSTEMATIC STUDY OF THE PROBLEM OF GRASS/BACTERIA ASSOCIATIVE SYMBIOSIS FOR BIOLOGICAL NITROGEN FIXATION. THE UNIVERSITY TEAM HAS ESTABLISHED THAT BACTERIA ARE ATTRACTED TO GRASS ROOT HAIRS, AND CAN INVADE BY WAY OF ROOT HAIRS, POINTS OF DAMAGE ON THE ROOTS AND AT THE JUNCTURE OF LATERAL ROOTS. THERE IS SOME INCONSISTENCY IN RESULTS, HOWEVER. TESTS OF 15N DILUTION TO MEASURE THE BIOLOGICAL NITROGEN FIXATION ARE INCOMPLETE, BUT IT IS HOPED THAT THIS WILL GIVE A RELIABLE INDEX OF THE CONTRIBUTION OF BIOLOGICAL NITROGEN FIXATION TO THE GROWTH OF GRASSES. TESTS WITH SOIL CORES DEMONSTRATED A LINEAR ACETYLENE REDUCTION, WHEREAS TESTS WITH EXCISED ROOTS WHICH HAD BEEN WASHED AND PRE-INCUBATED AT A LOW OXYGEN PRESSURE (P02) GAVE NON-LINEAR RATES OF ACETYLENE REDUCTION WITH TIME. RECOMMENDS THAT A SEARCH BE CONTINUED FOR GRASS/NITROGEN FIXATION ASSOCIATIONS AND BROADENED TO INCLUDE A VARIETY OF PLANTS AND BACTERIA IN ADDITION TO THE AZOSPIRILLUM ASSOCIATIONS. CONTINUED CONTACT WITH SIMILAR RESEARCH IN OTHER COUNTRIES IS ENCOURAGED. ALSO RECOMMENDS THAT THE CONTRACT BE EXTENDED 3 YEARS WITH ADDITIONAL FUNDING.