Water-use efficiency

Water-use efficiency is the amount of carbon gained or biomass produced per unit of water used. Its value depends on the organism, scale, and measurement period.

Stomata: Microscopic pores in plant surfaces that regulate gas exchange and water vapor loss. Their opening admits carbon dioxide while allowing water vapor to escape.
Carbon assimilation: The incorporation of inorganic carbon, chiefly carbon dioxide, into organic molecules. It is a common carbon-gain numerator in plant water-use measurements.
Crop yield: The harvested output of a crop per unit of land, often reported as mass or energy. Yield per water supplied is a practical agricultural form of efficiency.
Water productivity: The amount of useful output produced per unit of water consumed or supplied. It often emphasizes economic or harvested output rather than physiological carbon gain.
Transpiration: The movement of water through a plant and its evaporation from aerial surfaces, especially leaves. It is the main water loss paired with leaf carbon uptake.
Biomass: The mass of living or recently living biological material in a specified area, volume, or organism. Biomass gain is an alternative numerator to carbon assimilation.
Deficit irrigation: An irrigation strategy that applies less water than crops could use under full irrigation. It seeks greater production per unit water, sometimes at the cost of yield.
Transpiration efficiency: Plant dry matter produced per unit of water transpired, typically assessed over a defined period. It restricts water loss to transpiration, unlike measures that include soil evaporation.
Photosynthesis: The process by which organisms use light energy to convert carbon dioxide and water into organic compounds. Carbon gain in plants is largely generated by this process.
Evapotranspiration: The combined transfer of water to the atmosphere by evaporation and plant transpiration. It often supplies the water-use denominator at ecosystem or field scale.

Linked from 21 pages