ISHS Acta Horticulturae 801: International Symposium on High Technology for Greenhouse System Management: Greensys2007
EFFECTS OF TEMPERATURE INTEGRATION REGIMES WITH LOW PRE-NIGHT TEMPERATURES ON ENERGY CONSUMPTION, MICROCLIMATE, AND FRUIT YIELD IN EARLY GREENHOUSE TOMATO PRODUCTION |
| Authors: | Xiuming Hao, M.S. Borhan, Jingming Zheng |
| Keywords: | Lycopersicon esculentum, pre-night temperature, temperature integration, energy, microclimate, energy use efficiency |
| Abstract:
The effects of two temperature integration regimes (TI) with low pre-night temperatures on greenhouse microclimate, energy consumption, fruit yield and quality were investigated in a winter tomato crop to develop new temperature control strategy for improving energy use efficiency and early fruit yield. The two TI regimes were applied in 6 greenhouse compartments: Control TI – temperature integration with a pre-night temperature of 17°C, and New TI - temperature integration with a pre-night temperature of 13°C. The pre-night temperatures were applied from 6 to 9 pm for 3 hours. Same 24-h mean heating temperature for both TI regimes was set by adjusting the temperature set points in other periods during a day. Temperature integration was implemented using past/actual air temperatures with an integration period of 3 days. With both TI regimes, air temperature, leaf and fruit temperatures started to decline sharply in late afternoon and reached their lowest points around the end of pre-night period (9 pm). The change in fruit temperature always lagged behind that of leaf temperature. With the control TI, the lowest temperature and long term average temperature were similar between fruits and leaves. However, with the new TI, the lowest fruit temperature was about 1-2°C higher than the lowest leaf temperature during pre-night period. As of the result, the long term average fruit temperature with the new TI was 0.4°C higher than that of leaf temperature. The new TI also reduced vapor pressure difference between leaf and air (VPDleaf to air) during the pre-night period. With the new TI, early fruit yield especially for vegetative cultivar Big-Dena was higher than the control TI while energy consumption was lower (3-5%) than the control TI. Therefore, the new TI is an energy efficient temperature control strategy for early greenhouse tomato production. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
