Thermal sensitivity of grapevine leaves affected by Plasmopara viticola and water stress

Introduction: There has been an increasing interest in using non-destructive thermal imagery to determine leaf temperature of plants. Leaf temperature has been proven as an indicator of plant responses to various stressors (CHAERLE and VAN DER STRAETEN 2000), in particular for plant water availability (JONES 1999). The theory is that a reduced stomatal aperture restricts transpiration and consequently heat dissipation, resulting in an increase in leaf temperature (GATES 1964). The recognition of variations in leaf temperature led to the combined efforts to use infrared thermography and visible imagery to identify plant stress and non-destructively monitoring of plant’s physiological status, particularly for plant water availability in grapevines (JONES et al. 2002, STOLL and JONES 2007) or in response to various pathogen attacks (CHAERLE et al. 2004, OERKE 2006). The research objective was to test whether infrared thermography could be used to distinguish between confined and infected versus non-infected areas upon attack by Plasmopara viticola in grapevine leaves under varying water status conditions.