(PWP, permanent wilting percentage, wilting coefficient, wilting point)
As moisture is lost from the soil, the point at which the force with which the remaining moisture adheres to soil particles exceeds that exerted by plant roots. Plants are therefore unable to absorb moisture and wilting results. Since this condition arises from the amount of water present in the soil, plants will not recover unless water is added to the soil, i.e. the wilting is permanent. The permanent wilting point usually occurs when soil moisture is held with a force of about 15 MPa (15 bar). It is also measured as the percentage of moisture remaining in the soil after a specified test plant has wilted under defined conditions and will not recover unless water is added to the soil. Compare temporary wilting.
Subjects: Plant Sciences and Forestry — Ecology and Conservation.