Maize is the most important crop plant on the planet with close to a billion Mt grain produced per year. It carries out the most efficient mode of photosynthesis - C4, which affords high water and nutrient use efficiency, as well as superior efficacy in converting light energy into biomass. However, in intensively managed maize cultures, only approx. 68% of the theoretical (quantum-based) solar use efficiency is achieved, which indicates that a large and currently untapped potential for yield increases exists in this species. To date it is unknown which factors restrict or lower the efficacy of C4 photosynthesis. Further, few studies have investigated natural variance of photosynthesis within C4 plants. Within the FullThrottle project we will investigate what retracts the rate and efficiency of C4 photosynthesis, we will identify natural variance in maize photosynthesis, and elucidate its genetic cause thus providing a scientific basis for further improving the photosynthetic efficiency of maize (and indeed all other C4 crop species).