The Free Air Carbon dioxide Enrichment facility of the JKI (JKI-FACE) is located in Braunschweig, Germany and it is used to study genotype x environment interactions under field conditions with a range of environmental conditions (elevated CO2, ambient CO2, well-watered, rainfed, drought, biotic stress etc.). The facility consists of four FACE rings (octagons) with a diameter of 15.5 m, in which plants are grown under elevated CO2 in the field. Two Rainout-Shelters with an area of each 12 x 25 m are also available at the experimental field. The Rainout-Shelters automatically move over the plants only during rain events, while maintaining normal microclimatic conditions most of the time.