An Exotherm Sensor for Measuring the Cold Hardiness of Deep-supercooled Flower Buds by Differential Thermal Analysis1

Abstract

Abstract The low temperature exotherms of deep-supercooled flower buds have been found to be associated with freezing injury of the primordia. Differential thermal analysis of small buds with copper-constantan thermocouples often results in insufficient sensitivity, making it difficult to distinguish exotherms from background interference. The signal produced by the exotherm was significantly increased by utilizing a heat flux plate made from a thermoelectric module and thermal conducting paste. Differences in exotherms between nodes with one bud and with 2 buds could be detected with the thermoelectric module. More exotherms were detected from a given number of flower buds with the thermoelectric module than with thermocouples.