ISHS Acta Horticulturae 761: XXVII International Horticultural Congress - IHC2006: International Symposium on Advances in Environmental Control, Automation and Cultivation Systems for Sustainable, High-Quality Crop Production under Protected Cultivation
EFFECTS OF HEAT PLACEMENT ON ENERGY CONSUMPTION, MICROCLIMATE, PLANT GROWTH AND FRUIT YIELD OF GREENHOUSE TOMATOES GROWN ON RAISED-TROUGHS |
| Authors: | X. Hao, M.S. Borhan, A.P. Papadopoulos, J. Zheng, S. Khosla |
| Keywords: | grow pipe, leaf temperature, Botrytis, energy efficiency |
| Abstract:
Raised-trough production system (to grow plants on troughs hung 0.6–1.3 m above the ground) has become very popular in greenhouse tomato production in Canada because it facilitates intercropping, nutrient recycling and air circulation. With this system, the plants and growing media are further away from the heating pipes on the ground which may require increased heat utilization to maintain adequate plant microclimate. Several experiments were conducted at the Greenhouse and Processing Crops Research Centre (GPCRC) and in a commercial greenhouse to optimize the heating pipe placement for greenhouse tomato production on raised-troughs. It was found that the grow pipe (0.021 m in diameter, <50°C) placed at 0.55 m above the raised-trough inside the canopy of a double-row of tomato plants (GP55) increased leaf and fruit temperature, enhanced early fruit production (6%), and increased energy use efficiency. The use of the grow pipe also reduced the humidity (3–8%) inside crop canopy and the incidence of Botrytis (7%) compared to conventional heating pipe placement (no grow pipe). When the grow pipe was used instead of main ground pipe for dehumidification in fall tomato production, 10% of energy was saved without any fruit yield loss. It is recommended the grow pipe heating is not too early when the plants are very small to avoid excessive energy loss. Grow pipe placed at 1.5 m above the raised-trough (GP150) inside crop canopy also increased fruit yield (4%) and reduced the incidence of Botrytis (7%). However, it consumed slightly more energy than that of GP55. A new heating pipe placement (placing the main heating pipes at about 0.4 m below the raised-trough, in combination with the use of a grow pipe placed at 0.55 m above the raised-trough) also improved early fruit yield and energy use efficiency. Higher average vertical leaf temperature (0.3°C), lower humidity (1–4%), and an increased early yield (3.5%) were achieved with the new heat placement without any increase in energy consumption. | |
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