Instrument-based distortions of leaf/air temperature differences and interpretations of bean drought stress resistance

Abstract

Leaf/air temperature differences (?T) were measured for Phaseolus acutifolius Gray and three cultivars of Phaseolus vulgaris L. Two instruments having different measurement principles were used for leaf temperature and two sources of air temperature were used. Values of ? T differed depending on the instrument combination used, in this way affecting the interpretation of the plant's response to drought stress. Proper understanding and explanation of measuring techniques are shown to be an even more important prerequisite for parameters that are not easily observed directly.