Irrigation scheduling: advantages and pitfalls of plant-based methods
Hamlyn G. Jones*
Plant Research Unit, Division of Environmental and Applied Biology, School of Life Sciences, University of Dundee at SCRI, Invergowrie, Dundee DD2 5DA, UK
* Fax: +44 1382 34275. E-mail: [email protected]
Received 12 November 2003; Accepted 27 May 2004
This paper reviews the various methods available for irrigation scheduling, contrasting traditional water-balance and soil moisture-based approaches with those based on sensing of the plant response to water deficits. The main plant-based methods for irrigation scheduling, including those based on direct or indirect measurement of plant water status and those based on plant physiological responses to drought, are outlined and evaluated. Specific plant-based methods include the use of dendrometry, fruit gauges, and other tissue water content sensors, while measurements of growth, sap flow, and stomatal conductance are also outlined. Recent advances, especially in the use of infrared thermometry and thermography for the study of stomatal conductance changes, are highlighted. The relative suitabilities of different approaches for specific crop and climatic situations are discussed, with the aim of indicating the strengths and weaknesses of different approaches, and highlighting their suitability over different spatial and temporal scales. The potential of soil- and plant-based systems for automated irrigation control using various scheduling techniques is also discussed.
Key words: Dendrometry, sap-flow, stomatal conductance, thermography, water balance
Source: Journal of Experimental Botany 2004 55(407):2427-2436