INSTRUMENT TO MEASURE N2 FIXING AND NITROGENASE ACTION IN FIELD-GROWN LEGUMES

EXTENSIVE RESEARCH IS BEING CONDUCTED TO OPTIMIZE NITROGEN (N2) FIXATION RATE IN LEGUMINOUS CROPS, AND TO INTRODUCE N2-FIXING ABILITY INTO NONE-LEGUMINEOUS CROPS. THIS RESEARCH REQUIRES A METHOD TO CONDUCT CONTINUOUS, NININVASIVE MEASUREMENTS OF NITROGENASE ACTIVITY IN INTACT NODULATED ROOTS, PARTICULARLY IN FIELD STUDIES. CURRENTLY AVAILABLE METHODS ARE EITHER INHIBITORY OR ONLY PROVIDE MEASUREMENTS INTEGRATED OVER A GROWING SEASON. THIS SOLICITATION PRESENTS RESEARCH DIRECTED TOWARD THE DEVELOPMENT OF A FIELD-BASED INSTRUMENT TO ANLYZE HYDROGEN (H2) EVOLUTION FROM HUP LEGUME SYMBIOSES. THE DEVICE WILL PROVIDE MEASUREMENTS OF N2 FIXATION RATE AND NITROGENASE ACTIVITY. PHASE I WORK WILL INVOLVE RIGOROUS CHARACTERIZATION AND TESTING OF AN H2 SENSOR UNDER FIELD CONDITIONS. IN PARTICULAR, SENSOR SENSITIVITY TO TEMPERATURE AND OTHER BACKGROUND CONDITIONS WILL BE ASSESSED. A RELIABLE METHOD FOR CALIBRATION OF THE H2 SENSOR SHALL THEN BE DEVISED. ALSO, A PROTOTYPE, NOVEL OPEN-FLOW GAS EXCHANGE SYSTEM WILL BE CONSTRUCTED, WHICH IS CAPABLE OF FLUSHING THE LEGUME RHIZOSPHERE WITH DIFFERENT GASES WHILE ANALYZING H2 EVOLUTION. THE FINAL RESEARCH STAGE SHALL ASSESS THE EFFECTIVENESS OF MONITORING NITROGENASE ACTIVITY USING THIS H2 METHOD, AND IDENTIFY POTENTIAL PROBLEMS (IF ANY) ARISING FROM H2 OXIDATION IN THE SOIL BY BACTERIA.