Articles
EFFECTS OF TEMPERATURE INTEGRATION WITH LOW PRE-MORNING TEMPERATURES ON MICROCLIMATE, FRUIT YIELD AND ENERGY USE EFFICIENCY IN GREENHOUSE TOMATO PRODUCTION
Article number
893_89
Pages
815 – 820
Language
English
Abstract
Temperature integration (TI) has been adopted as a greenhouse temperature control strategy to improve energy use efficiency.
The key to the success for TI application is to lower the temperature during the period of high energy demand without compromising crop environment and productivity.
The lowest outside temperature and the highest energy consumption usually occur during the pre-morning (PM) period.
Three TI regimes with low PM temperatures were investigated on a winter/spring tomato crop in 6 greenhouse compartments in this study: PMAT17 (the control) – 17C PM temperature and controlled with air temperature (AT), PMAT13 – 13.5C PM temperature and controlled with AT, PMPT13 – 13.5C PM temperature and controlled with the plant temperature (PT) measured with infra-red cameras.
Temperature integration was implemented using actual temperature (temperature realized in preceding days) with 3 days of integration period.
The PM temperatures were applied from 3 to 6 am for 3 hours.
Same 24-h average temperature for all 3 TI regimes was maintained by adjusting temperatures in other periods during a day.
Average air temperature inside the crop canopy with PMAT13 and PMPT13 was similar to PMAT17 while the air temperature above the canopy was lower than PMAT17. The dew point temperature and relative humidity inside crop canopy with PMAT13 and PMPT13 was lower than PMAT17, which indicated that PMAT13 and PMPT13 did not result in any increase in the risk of water condensation.
PMAT13 and PMPT13 did not save energy in February.
However, they reduced the energy use from March to May by 6-8%, in comparison to PMAT17. Except for a very vegetative cultivar with poor tolerance to low temperature, PMAT13 and PMPT13 did not adversely affect (even increased) fruit yield.
Therefore, the TI regime with low pre-morning temperature is a useful temperature control strategy for improving energy use efficiency in greenhouse tomato production.
The key to the success for TI application is to lower the temperature during the period of high energy demand without compromising crop environment and productivity.
The lowest outside temperature and the highest energy consumption usually occur during the pre-morning (PM) period.
Three TI regimes with low PM temperatures were investigated on a winter/spring tomato crop in 6 greenhouse compartments in this study: PMAT17 (the control) – 17C PM temperature and controlled with air temperature (AT), PMAT13 – 13.5C PM temperature and controlled with AT, PMPT13 – 13.5C PM temperature and controlled with the plant temperature (PT) measured with infra-red cameras.
Temperature integration was implemented using actual temperature (temperature realized in preceding days) with 3 days of integration period.
The PM temperatures were applied from 3 to 6 am for 3 hours.
Same 24-h average temperature for all 3 TI regimes was maintained by adjusting temperatures in other periods during a day.
Average air temperature inside the crop canopy with PMAT13 and PMPT13 was similar to PMAT17 while the air temperature above the canopy was lower than PMAT17. The dew point temperature and relative humidity inside crop canopy with PMAT13 and PMPT13 was lower than PMAT17, which indicated that PMAT13 and PMPT13 did not result in any increase in the risk of water condensation.
PMAT13 and PMPT13 did not save energy in February.
However, they reduced the energy use from March to May by 6-8%, in comparison to PMAT17. Except for a very vegetative cultivar with poor tolerance to low temperature, PMAT13 and PMPT13 did not adversely affect (even increased) fruit yield.
Therefore, the TI regime with low pre-morning temperature is a useful temperature control strategy for improving energy use efficiency in greenhouse tomato production.
Authors
X. Hao, L. Zhang, MD.S. Borhan, S. Khosla
Keywords
climate control, energy, Lycopersicon esculentum
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