ISHS Acta Horticulturae 278: Symposium on Scheduling of Irrigation for Vegetable Crops under Field Condition
PLANT WATER RELATIONS AND IMPLICATIONS FOR IRRIGATION SCHEDULING |
| Author: | H.G. Jones |
| Abstract:
This paper reviews the ways in which plants sense soil water deficits and the relevance of this information to irrigation scheduling. Recent evidence suggests that leaf water status is not the most useful indicator of plant water stress, and cannot therefore be used as the primary indicator of irrigation need as has sometimes been suggested. In fact leaf water status depends in a complex manner on soil water availability and on environmental and physiological factors. It is now clear that in some situations soil water status is sensed by the roots and this information is signalled to the shoots, perhaps by means of chemical messengers such as abscisic acid (ABA). As alternatives to direct estimates of plant and soil water status, it is possible to base irrigation scheduling on indirect measures that depend on the plant response to water status. These approaches, include the use of plant growth or dimension changes, and stomatal aperture or leaf temperature. One particular indirect measure that is discussed and evaluated in this paper is the use of xylem cavitation. The potential merits of direct and indirect measures of water status are compared, with particular emphasis on the estimation of root water potential and the use of xylem cavitation. | |
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