Water Availability to Plants

Abstract

Water is essential for plant growth, and modeling of water availability to plants, root water uptake and actual transpiration rates is important to support hydrological, meteorological and crop growth modeling. Soil texture, soil structure and plant rootability are the crucial factors in determining the amount of soil water available for plants. In a simple approximation, available and non-available water is often defined in terms of concepts like field capacity and permanent wilting point. In this chapter these concepts are discussed, together with more advanced approaches. Topics include the water potentials in the soil-plant-atmosphere system, the relation between transpiration and dry matter accumulation, zones of soil water availability to plants, the limiting water content for optimum plant transpiration and growth, the role of the matric flux potential, a composite soil hydraulic property, and aspects of root system geometry and how they affect crop water availability.