Evaluation of the effects of cool night temperatures (10°C) and cool day/night temperatures (15°C/10°C) during reproductive development of soybeans on photosynthetic and respiratory gas-exchange, chlorophyll fluorescence, day/night carbon partitioning and export with respect to the feedback induced limitations of photosynthesis, flowering, seed filling and yield in existing soybean germplasm suggested adaptation for northern expansion. The influence of temperature on soybean respiration and photosynthesis needs to be characterized at three key growth stages: mid vegetative development; flowering; and mid seed filling. Soybean germplasm will be provided by Dr. Elroy Cober who, through Eastern Cereals and Oilseeds Research Centre select of new adapted soybean germplasm in Manitoba and Saskatchewan through CFCRA Cluster supported projects. Physiological traits following a cool temperature stress, such as photosynthetic tolerance to the feedback limitations, photosynthesis recovery and capacity for starch mobilization and carbon export, will be studied with an emphasis on developing a quicker and simpler screening procedure for cool stress tolerance. Improving the capacity for soybeans to function at cooler temperatures may dramatically increase seed yield in the cool season regions.