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Measuring Plant Stress with an Infrared Thermometer

1990; American Society for Horticultural Science; Volume: 25; Issue: 12 Linguagem: Inglês

10.21273/hortsci.25.12.1535

2327-9834

Jerry L. Hatfield,

Greenhouse Technology and Climate Control

Fig. 1. Influence of IRT distance from the target on the area seen by the IRT when it is positioned perpendicular to the target, for two fields of view (FOV). Infrared thermometers are rapid, reliable instruments for measuring foliage temperature. These instruments are relatively simple to use with only a few considerations, e.g., field of view, target dimensions, and calibration. The foliage temperature can be incorporated into crop water stress indices that have been related to soil water availability and leaf water potential. The number of samples that need to be collected is relatively small. The infrared thermometer provides a technique for the remote detection of stress in all types of plants. Plant stress measurements with the hand-held infrared thermometer (IRT) have become increasingly popular in the last 10 years following the introduction of the portable, battery-powered IRT. Digital displays of foliage temperature allowed for quick and easy measurements. Possible sources of error and potential uses of the IRT to measure water stress will be presented. It is assumed that the reduction of soil water will result in stomata] closure and cause an increase in foliage temperature. In practice, any situation (e.g., disease, fertility, root pruning) that affects transpiration will affect foliage temperature.