ABSTRACT
Permanent wilting point (PWP) is defined as the largest water content of a soil at which indicator plants, growing in that soil, wilt and fail to recover when placed in a humid chamber. It is often estimated by the water content at 1.5MPa soil matric potential.[1] The water content is typically expressed on a weight (gm3) or volume (m3m3) basis. As the lower boundary, PWP, along with the upper boundary determined at field capacity, establishes the size of the reservoir of water held in the soil that may be withdrawn by plants, known as plant available water. Field capacity is primarily a function of soil characteristics, while PWP is the product of a combination of plant, soil, and atmosphere factors.
