I wonder if anyone has done any work with temperatures and tropical fruit trees. Can be accomplished using any good infrared temperature meter. May be a good way to control irrigation quick and inexpensive, if it works
Noncontact infra-red heat sensors measure plant stress by comparing temperature variances between ambient air & plant foliage
Professional laser thermometer with advanced temperature processing; built-in socket accepts commercially available K-type thermocouple (not included)
Measurement temperature range: -76F to 1157F
Accuracy: +/- 1.8F
Response time: 1 Second
Distance:Spots: 16:1 (scroll down for explanation)
Plant Stress Monitoring Directions
Note: The USDA has researched the stress level in plants as a function of temperature rise above ambient air temperature. The IR gun provides a simple, fast and accurate means of testing the differential temperature (Δ T).
Conditions required for testing:
Plant leaf surface must be dry.
Use only when wind is blowing at less than 10 mph.
Keep the sunlight at your back.
Use a sheet of plain white paper for determining ambient air temperature.
Take I.R. readings from foliage only during the peak sunlit hours of the day, when stress is most likely to occur. Therefore, take readings from 11 AM to 4 PM during the summer and from 1 PM to 3 PM during the winter.
If air temperature is much cooler than normal, then I.R. plant stress will not be measurable with this instrument.
You must have at least 2 minutes of sunlight immediately following an interruption by clouds.
Directions for taking differential temperature readings between ambient air and plant leaf surfaces:
More Here:
http://www.pikeagri.com/component/virtuemart/plant-testing-meters/infra-red-plant-stress-monitors/infrared-heat-sensor-plant-stress-detail?Itemid=0