LOW-TEMPERATURE EXOTHERM MEASUREMENT USING INFRARED THERMOGRAPHY

Infrared thermography was used successfully to measure the exotherm te mperatures during freezing of well-watered and drought stressed branch es of jojoba [Simmondsia chinensis (Link) Schneider]. The exotherms we re visualized easily as color changes on the monitor, while computer a nalysis software was used to plot the resulting temperature vs. time c urves, suggesting that freezing sensitivity of jojoba is governed by s upercooling. Each branch froze as a unit, and distinct initiation site s were absent. A second, previously tested method of differential ther mal analysis was used simultaneously and confirmed the accuracy of the infrared technique. The actual freezing temperature for well-watered tissue was higher (-8C) than for tissue subjected to drought (-10C).