Water-use efficiency

Water use efficiency (English water -use efficiency, abbreviation WUE ) is defined as the ratio of fixed carbon to water transpired in plants. Plants fix the so-called dark reaction of photosynthesis carbon dioxide. This CO2 is thereby taken through the open stomata, but which water vapor escapes. In particular, plants in arid regions must therefore fix as much CO2 in a short time, in order not to lose too much water. Such plants, such as C4 plants or plants with Crassulacean acid metabolism, have a high water use efficiency.

Under drought stress (water stress) the stomata in the leaves of the plants to be closed on the induced abscisic acid and water use efficiency increased.

Depending on the determination of water use efficiency, a distinction is made ​​between:

  • Water use efficiency of production (English water -use efficiency of productivity or integrated water -use efficiency ): it is the ratio of recovered biomass to the water loss in biomass production.
  • Water use efficiency of photosynthesis (English photosynthetic efficiency of water -use ): it is determined by means of gas exchange measurements. If it represents the ratio of the recovered during photosynthesis carbon to water loss through transpiration, it is referred to as "instantaneous water -use efficiency". If instead of the transpiration of water vapor conductance of the stomata used, they are called " intrinsic water -use efficiency".


  • Botany
  • Plant Physiology
  • Ecosystem Research