A parameter of thermographic difference used in sunny summer midday and its significance

摘要

A large number of thermo-image measurements are useful in determining the water and energy status of ornamental tree or shrubs, especially when using certain improved parameters and methods. With these parameters and proper methods, data comparability in thermo-image analyses of ornamental tree/shrubs have been improved. In a large number of thermographic measurements, we found a significantly high-image temperature or ''fever" status in stressed tree or shrubs in sunny summer midday because of their transpiration cooling failure. Leaf withering, scorching, reddening, shedding and green losing can be the typical symptom patterns after persistent "fever" which is a dangerous signal unadapted to local environment and originate from persistent water and energy imbalance. The utilization of parameter of thermo-difference between leaf and finger of observer (TDlf) supports this idea.