** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** INCREASING THE YIELD OF SOYBEAN ALLOWS FARMERS TO MAXIMIZE PROFIT AND HAS THE POTENTIAL TO INCREASE OUTPUT WITHOUT EXPANDING THE AREA OF LAND UNDER CULTIVATION. THIS IS IMPORTANT FOR EFFORTS DIRECTED AT THE SUSTAINABLE INTENSIFICATION OF AGRICULTURE. IT IS COMMONLY ASSUMED THAT SOYBEAN YIELD IS LIMITED BY THE AMOUNT OF CARBON FIXED THROUGH PHOTOSYNTHESIS, WHICH IS SEEN IN HIGH RATES OF FLOWER ABORTION DURING SEED PRODUCTION. IT FOLLOWS THAT PLANTS BRED TO HAVE GREATER RATES OF PHOTOSYNTHESIS MAY HAVE INCREASED YIELD. HOWEVER, THERE IS NO CONSENSUS OVER THE EXTENT TO WHICH THIS ASSUMPTION IS VALID, AND THE GENETIC BASIS OF VARIATION IN PHOTOSYNTHESIS IS POORLY UNDERSTOOD. THEREFORE, WE AIM TO TEST WHETHER A SPECIFIC ASPECT OF PHOTOSYNTHESIS - THE RATE AT WHICH IT IS TURNED ON DURING SUNFLECKS - HAS A SIGNIFICANT IMPACT ON SOYBEAN YIELD, AND GAIN INSIGHT INTO THE GENETIC CAUSE OF VARIATION IN THIS TRAIT. THIS WILL BE ACHIEVED BY (1) GENERATING SOYBEAN LINES WITH VARIABLE RATES OF PHOTOSYNTHESIS THROUGH EDITING OF A GENE KNOWN TO BE RELATED TO THIS PROCESS, (2) COMPARING RATES OF PHOTOSYNTHESIS UNDER FIELD CONDITIONS OF TWO LINES OF SOYBEAN FOR WHICH YIELD DATA IS AVAILABLE AND (3) DEVELOPMENT OF A HIGH-THROUGHPUT METHOD TO TEST RATES OF ACTIVATION OF PHOTOSYNTHESIS FOR FUTURE GENETIC MAPPING STUDIES.THE RESOURCES, INFORMATION AND METHODS DEVELOPED DURING THIS PROPOSAL WILL PROVIDE FUNDAMENTAL UNDERSTANDING OF THE LINK BETWEEN AN ASPECT OF PHOTOSYNTHESIS AND YIELD THAT CAN INFORM FUTURE EFFORTS TO IMPROVE SOYBEAN.