Abstract
Greenhouse crop production in semi-arid climates is desirable because high solar radiation levels are consistent year round. The use of evaporative cooling will further increase yields and crop consistency. However, these regions typically receive less than 500 mm of rain annually, making water use management a critical concern. This study evaluated water use for irrigation (WUI) and pad-and-fan (WUPF) evaporative cooling systems in a single-span, polyethylene-covered greenhouse in Tucson, Arizona, from March to October 2006. A single-use, non-recirculating irrigation system delivered water to hydroponically grown tomatoes. The pad-and-fan system was computer controlled to maintain day/night air temperatures of 24C/18C. The total eight-month WUI and WUPF were 780 and 1450 L m-2, respectively. WUI increased steadily from 4.3 L m-2 d-1 during crop establishment to 7.2 L m-2 d-1 when the plants were mature. WUPF increased from 1.1 L m-2 d-1 during early spring to a peak of 11 L m-2 d-1 during the hottest, driest outside conditions. The water use efficiency (WUE, kg yield per m3 water use) of the irrigation and pad-and-fan cooling systems was 30 and 16 kg m-3, respectively. When WUE was calculated by combining WUI and WUPF, the total greenhouse WUE was 11 kg m-3. Theoretically, using a 100% recirculating irrigation system could have produced a greenhouse WUE of 13 kg m-3. This study demonstrates that although greenhouses achieve high annual yields with low irrigation rates, using an evaporative cooling system reduces greenhouse WUE to field WUE levels. To minimize greenhouse water use while maintaining high crop yields, this study recommends further examination of the use of recirculating irrigation systems, variable-speed fans to improve climate control, alternative cooling systems, and drought-tolerant crops.
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Claims 9
Claim · model-written summary
Eight-month irrigation water use was 780 L m-2.
- Taxon
- tomatoes
Solanum lycopersicumt0 - Outcome
- WUIe0
- Value
- 780e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The total eight-month WUI and WUPF were 780 and 1450 L m-2, respectively.”
t0“tomatoes”
Claim · model-written summary
Eight-month pad-and-fan water use was 1450 L m-2.
- Taxon
- tomatoesSolanum lycopersicumt0
- Outcome
- WUPFe0
- Value
- 1450 L m-2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The total eight-month WUI and WUPF were 780 and 1450 L m-2, respectively.”
t0“tomatoes”
Claim · model-written summary
Irrigation water use rose from crop establishment to maturity.
- Taxon
- tomatoesSolanum lycopersicumt0
- Outcome
- WUIe0
- Direction
- increased steadilye0
- Value
- 4.3 L m-2 d-1e0
- Qualifier
- 7.2 L m-2 d-1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“WUI increased steadily from 4.3 L m-2 d-1 during crop establishment to 7.2 L m-2 d-1 when the plants were mature.”
t0“tomatoes”
Claim · model-written summary
Cooling water use rose from early spring to a peak in the hottest, driest conditions.
- Taxon
- tomatoesSolanum lycopersicumt0
- Outcome
- WUPFe0
- Direction
- increasede0
- Value
- 11 L m-2 d-1e0
- Qualifier
- 1.1 L m-2 d-1 during early springe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“WUPF increased from 1.1 L m-2 d-1 during early spring to a peak of 11 L m-2 d-1 during the hottest, driest outside conditions.”
t0“tomatoes”
Claim · model-written summary
Irrigation water use efficiency was 30 kg m-3.
- Taxon
- tomatoesSolanum lycopersicumt0
- Outcome
- water use efficiencye0
- Value
- 30e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The water use efficiency (WUE, kg yield per m3 water use) of the irrigation and pad-and-fan cooling systems was 30 and 16 kg m-3, respectively.”
t0“tomatoes”
Claim · model-written summary
Pad-and-fan cooling water use efficiency was 16 kg m-3.
- Taxon
- tomatoesSolanum lycopersicumt0
- Outcome
- water use efficiencye0
- Value
- 16 kg m-3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The water use efficiency (WUE, kg yield per m3 water use) of the irrigation and pad-and-fan cooling systems was 30 and 16 kg m-3, respectively.”
t0“tomatoes”
Claim · model-written summary
Combined greenhouse water use efficiency was 11 kg m-3.
- Taxon
- tomatoesSolanum lycopersicumt0
- Outcome
- total greenhouse WUEe0
- Value
- 11 kg m-3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When WUE was calculated by combining WUI and WUPF, the total greenhouse WUE was 11 kg m-3.”
t0“tomatoes”
Claim · model-written summary
A fully recirculating irrigation system was calculated to produce 13 kg m-3 greenhouse WUE.
- Taxon
- tomatoesSolanum lycopersicumt0
- Treatment
- 100% recirculating irrigation systeme0
- Outcome
- greenhouse WUEe0
- Value
- 13 kg m-3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Theoretically, using a 100% recirculating irrigation system could have produced a greenhouse WUE of 13 kg m-3.”
t0“tomatoes”
Claim · model-written summary
Evaporative cooling reduced greenhouse WUE to field WUE levels.
- Taxon
- tomatoesSolanum lycopersicumt0
- Treatment
- evaporative cooling systeme0
- Outcome
- greenhouse WUEe0
- Direction
- reducese0
- Comparator
- field WUE levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“using an evaporative cooling system reduces greenhouse WUE to field WUE levels.”
t0“tomatoes”
The same questions in other papers
processing · physiology: water · Solanum lycopersicum (tomato)Positive and negative results
3 papers in the same direction as this paper · 13 in the opposite direction
- positive
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See all 17 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.