Practice-Oriented Leaf Temperature Measurements in Heated Greenhouses

Abstract

The use of different techniques of leaf temperature measurement in greenhouses was studied in a practice-oriented trial with ornamental plants. Measurements with contact thermocouples, injection sensors, in- frared sensors, and thermographical methods were carried out and com- pared in a conventional greenhouse with convection heating pipes and in a greenhouse with a special radiation heating system. It was shown that leaf temperature distribution within the greenhouse is very important, especially if radiation heating systems are used. Furthermore, it was demonstrated that injection temperature sensors can be employed for greenhouse climate control. The use of infrared sensors proved difficult, though possible in principle. In contrast to this, temperature measure- ment through image-based thermography did not provide satisfactory results.