Permanent wilting point (PWP) or wilting point (WP) is defined as the minimum amount of water in the soil that the plant requires not to wilt. If the soil water content decreases to this or any lower point a plant wilts and can no longer recover its

turgid Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall. It is also called ''hydrostatic pressure'', and is defined as the pressure in a fluid measured at a certain point within itself when at equilibriu ...

ity when placed in a saturated atmosphere for 12 hours. The physical definition of the wilting point, symbolically expressed as or , is said by convention as the

water content Water content or moisture content is the quantity of water contained in a material, such as soil (called soil moisture), rock, ceramics, crops, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as ...

at of suction pressure, or negative

hydraulic head Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22. It is usually measured as a liquid surface elevation, expressed in units of length, ...

History

The concept was introduced in the early 1910s.

Lyman Briggs Lyman James Briggs (May 7, 1874 – March 25, 1963) was an American engineer, physicist and administrator. He was a director of the National Bureau of Standards during the Great Depression and chairman of the Uranium Committee before America e ...

and Homer LeRoy Shantz (1912) proposed the wilting coefficient, which is defined as ''the percentage water content of a soil when the plants growing in that soil are first reduced to a wilted condition from which they cannot recover in approximately saturated atmosphere without the addition of water to the soil''. See

pedotransfer function In soil science, pedotransfer functions (PTF) are predictive functions of certain soil properties using data from soil surveys. The term ''pedotransfer function'' was coined by Johan Bouma as ''translating data we have into what we need''. The mo ...

for wilting coefficient by Briggs. Frank Veihmeyer and Arthur Hendrickson from University of California-Davis found that it is a constant (characteristic) of the soil and is independent of environmental conditions.

Lorenzo A. Richards Lorenzo Adolph Richards (April 24, 1904 – March 12, 1993) or known as ''Ren'' was one of the 20th century's most influential minds in the field of soil physics. Biography Early life Lorenzo A. Richards was born on April 24, 1904, in the town of ...

proposed it is taken as the soil water content when the soil is under a pressure of −15 bar.{{cite journal, author1=Veihmeyer, F.J. , author2=Hendrickson, A.H. , name-list-style=amp , year=1928, title=Soil moisture at permanent wilting of plants , journal=Plant Physiol. , volume=3 , pages=355–357, doi=10.1104/pp.3.3.355, pmid=16652577, issue=3, pmc=440017

References

Soil physics Hydrology Forest pathology

History

See also

References