To come

Climate change is expected to reduce global food production in part due to low crop resilience. The greatest threats to crop production are those related to changes in temperature and water availability. Low resilience has been attributed to selection under high-input environments, but in the case of heat and drought tolerance this attribution relies on a pedagogic model that is difficult to support empirically. Three challenges to increasing resilience include modifying selection criteria to focus on stress adaptation mechanisms that maintain or stabilize yield, ensuring the presence and efficiency of stress- tolerance genes, and expanding the use of minor crops which may have better qualities for resilience than major crops. Progress has been made in stress adaptation through improvement of yield components under water-limited environments. These include transpiration efficiency (TE), drought escape, and harvest index. Scope remains for further improving TE. Progress in stress adaption is threatened, however, by effects of rising temperature. Higher temperatures increase vapor pressure deficit, which lowers water-use efficiency, and affects crop development and its synchrony with soil water availability. Other environmental stresses indirectly related to climate change also threaten food security, such as competition for water and a prevalence of nutrient-depleted soils in developing countries, particularly in Africa. Genetic and environmental (including management) approaches exist for adaption and mitigation to these stresses, but research is underfunded. Social changes also place stresses on our capacity to sustainably produce sufficient food for the planet. These include dietary changes and urbanization, which may limit consumption of minor crops, as well as public perception of agriculture and an associated dearth of youth entering agricultural fields. The role and limits of crop physiology in addressing these challenges are discussed.