Articles
CONTROL AND OPTIMIZATION OF THE GREENHOUSE ENVIRONMENT USING INFRA-RED SENSORS
Article number
633_17
Pages
145 – 152
Language
English
Abstract
Wide-angle, infra-red (IR) sensors were linked directly to a greenhouse climate control computer, and were used successfully both to monitor plant canopy temperature (CT), and to control greenhouse heating and cooling on the basis of CT. Summer trials used pot chrysanthemums and dieffenbachias, and relationships between CT and air temperature (AT) under the trial conditions are given.
Flowering crops typically showed high CT values in summer.
IR monitoring on a commercial begonia nursery showed that CT at night was generally about 2°C below AT in summer, but that CT exceeded AT during the day by up to 7°C. Differences between CT and AT were found to mirror changes in photosynthetic photon flux density (PPFD). Allowing AT to fall at dawn to give compact plants (DROP) did not always result in comparable reductions in CT. This was because increasing irradiance at the start of day tended to nullify the effect of lowered AT on CT. Potential benefits of controlling greenhouse operation on the basis of CT include avoidance of plant stress in summer, improved environmental optimization, more precise crop scheduling and, possibly, energy savings.
Control based on CT is an example of the speaking plant approach to crop management, and commercial activity in the Netherlands suggests that this is at last becoming a reality.
Flowering crops typically showed high CT values in summer.
IR monitoring on a commercial begonia nursery showed that CT at night was generally about 2°C below AT in summer, but that CT exceeded AT during the day by up to 7°C. Differences between CT and AT were found to mirror changes in photosynthetic photon flux density (PPFD). Allowing AT to fall at dawn to give compact plants (DROP) did not always result in comparable reductions in CT. This was because increasing irradiance at the start of day tended to nullify the effect of lowered AT on CT. Potential benefits of controlling greenhouse operation on the basis of CT include avoidance of plant stress in summer, improved environmental optimization, more precise crop scheduling and, possibly, energy savings.
Control based on CT is an example of the speaking plant approach to crop management, and commercial activity in the Netherlands suggests that this is at last becoming a reality.
Authors
F.A. Langton, J.S. Horridge, M.D. Holdsworth, P.J.C. Hamer
Keywords
speaking plant, canopy temperature, plant stress, environmental optimization, chrysanthemum, dieffenbachia, begonia
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