The point at which the amount of water in the soil has dropped to such a level that the plants begin to wilt and will not recover, even if moved to a cool and dark place, unless more water is added to the soil. It occurs when the water potential of the soil is the same as, or lower (more negative) than, the water potential of the plant. The amount of water retained in the soil when the permanent wilting point is reached varies depending on the plant species and the type of soil. See also field capacity. |
