Potato physiology determines how genetically-encoded developmental attributes interact with local environmental conditions, as modified through agricultural practice, to produce the final crop. This chapter highlights how physiological responses of potato to management choices made by growers and environmental conditions during growth and post-harvest storage determine yield, quality and sustainability. The development of the potato plant is described and special emphasis is given to the interdependence of tuber growth and canopy development. Key aspects of the root system architecture are reviewed. The chapter discusses research assessing the sensitivity of potato yield to water and nutrient availability, highlighting the adverse effects of water deficits and high temperatures on tuber growth, quality and overall sustainability.