SOME MEASUREMENTS OF MICRO-CLIMATE IN A GLASSHOUSE WITH A TOMATO CROP

The literature suggests that the incidence of fungus diseases is closely related to leaf wetness and atmospheric relative humidity. In a glasshouse tomato crop the effect of automatic humidity control on the incidence of Cladosporium fulvum and Botrytis cinerea has been investigated, but clear evidence of the extent of changes in the crop micro-climate was not obtained. This paper describes an investigation of the differences of temperature and r.h. in the path, within the foliage and at the canopy of a glasshouse tomato crop, in particular during conditions likely to produce near saturation of the atmosphere and the deposition of moisture on the plants. Leaf, fruit and glass temperatures were also measured. Fairly extensive differences of temperature and humidity between the various positions were found, the biggest differences occurring between the open path position and the crop canopy, where radiation losses to the glass produced temperature depressions and higher r.h. During slow cooling with the glasshouse ventilators closed, r.h. at the canopy approached 100%. © 1969.