Use of Pressure Bomb Measurements to Estimate Root Water Potentials1

Abstract

AbstractPressure bomb measurements were used to estimate root water potentials of soil‐grown pepper (Capsicum annum L. cv. ‘California Wonder’) plants. Bomb measurements taken on roots of wilted pepper plants in dry soil overestimated the water potential by as much as 8 bars when roots were known to be damaged. When plants were equilibrated at low water potentials (‐10 to ‐14 bars) and the roots were undisturbed, differences between water potentials in the plant roots and top were 0.4 bars or less.Increases in water potential with time were observed in both stressed and well‐watered plants where roots were not damaged but where there was no attempt to equilibrate the water potential gradient. Root resistance, root pressure and unsaturated conductivity of the soil all influence the tune dependence of root water potential.