Improving Understanding of Microclimate Heterogeneity within a Contemporary Plant Growth Facility to Advance Climate Control and Plant Productivity

Abstract

Greenhouse crop production is maximized by maintaining optimal growing conditions. Accurate management of climate conditioning equipment based on measurements of the internal greenhouse microclimate is necessary to optimize crop production. Traditionally, greenhouse microclimate is monitored by a single suite of sensors located at a fixed (often central) location that is considered representative of the entire greenhouse climate. To advance greenhouse crop production additional sensors may better represent greenhouse microclimate heterogeneity and improve performance of climate conditioning equipment. However, elucidating the proper number and distribution of additional sensors requires investigation. Distributed high resolution air temperature (n = 63), relative humidity (n=63), and incoming solar radiation data were collected between May 9th, 2012 and September 5th, 2012 to test the efficacy of conventional centrally located sensors to characterize the spatial and temporal climate variability inside three contemporary greenhouse facilities. Results indicate substantial microclimate heterogeneity with mean horizontal temperature gradients of as much as 5.0°C/m, and mean horizontal VPD gradients of 1.5 kPa/m. Most substantially, the maximum vertical temperature gradient was 11.65°C/m. Results indicate that as few as five properly deployed sensor assemblages (e.g. temperature, humidity, solar radiation) may be necessary to more accurately monitor horizontal and vertical microclimate heterogeneity in a typical greenhouse room. This would improve climate conditioning accuracy and improve the homogeneity of the internal greenhouse climate, which may result in increased productivity and profits for greenhouse managers.