ABSTRACT
Growth is directly related to plant water potential. The higher the water potential (less negative), the greater is the rate of growth. Figure 7.1 shows this relationship for snap beans (Phaseolus vulgaris L.). As the plant approaches the permanent wilting point [often considered to be about −1.5 MPa or −15 bar (Kirkham 2005, pp. 104-107)], the plant dies due to water de£cit. Growth of most plants stops before the permanent wilting point is reached. The curve in Figure 7.1 has been drawn assuming that factors such as light, CO2, and nutrients are constant (Gardner 1973, p. 223).
