Agricultural production is strongly influenced by climate, and any change in climate can reduce crop productivity and put the food security of the world’s growing population at risk. Barley is one of the most important cereal species worldwide in terms of production, being used both in animal and human food as well as in the malting industry. Climate predictions suggest a continuous increase in CO2 in the atmosphere, associated with higher temperatures and an increase in the duration and intensity of droughts.
Climate change supposes an alteration of the main environmental factors that affect the productivity and quality of crops that, together with the increase in food demand by the world’s largest population, puts future food security in risk. The scenarios predict an increase in atmospheric CO2, a higher temperature and an increase in the intensity and duration of droughts, which will imply changes in productivity and quality. An alternative is the search for species more tolerant to these environmental stresses, quinoa being one of the possible species, thanks to its high tolerance to drought and salinity.
The exchange of water for carbon between the vegetation and the atmosphere constitutes the most important feedback mechanism underlying the regulation of water and carbon (C) cycles by the terrestrial biosphere. Water use efficiency (WUE) is the trait that serves to describe this intimate link between the C and water cycles and is a crucial parameter incorporated in many land-surface-models to predict vegetation-climatic feedbacks under future climate change scenario. WUE can be estimated using multiple approaches and methodologies concerning different temporal spatial and temporal scales.