Thermal image analyser for crops

A thermal image analyser for determining the stomatal conductance of a plant, comprising:

• a thermal imaging device, configured to capture a thermal image of at least a portion of the plant that is in an imaging region of the thermal imaging device, and
• a processor device, configured to analyse the captured thermal image and to determine the stomatal conductance of the plant on the basis of the captured thermal image,
• wherein the thermal image analyser further comprises:
• a reference object, which comprises a reference surface and a thermal sensor, wherein the thermal sensor is connected to the reference surface and configured to emit a temperature sensor signal that is representative for a surface temperature of the reference surface,
• wherein the reference object further comprises a cap, which is formed by a spheroid wall and wherein the reference surface is formed by a spherical outer surface of the spheroid wall,
• wherein the reference object is adapted to be positioned, such that at least a portion of the reference surface is located in the imaging region of the thermal imaging device,
• wherein the temperature sensor signal is adapted to be transmitted to the processor device, and
• wherein the processor device is configured to compensate the stomatal conductance on the basis of the portion of the plant and the reference surface in the imaging region of the thermal imaging device shown in the captured thermal image and the temperature sensor signal.