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UBC Theses and Dissertations
The prediction and validation of greenhouse tomato yield using mathematical models and expert systems Tang, Winston C.
Abstract
Greenhouse tomato yields were predicted using two mathematical models developed in this study - the empirical and deterministic models. Weekly yield predictions for an entire growing season were compared with actual yields and results from an expert system model developed by the Agassiz Research Station. The deterministic math model involved using first principle equations of photosynthesis and respiration to simulate crop growth. Utilizing a known tomato yield conversion factor, net photosynthesis rates (Pnet) were converted to weekly yield predictions and compared with actual recorded yields. A deterministic model using two week cumulations of Pnet converted to yield was used successfully to predict actual tomato yields 6 weeks ahead of time with a root-mean-square-error (RMSE) of 0.38 kg/m2. The empirical math model employed regression techniques to fit historical greenhouse climate data to recorded yields. Correlations between light, temperature, and weekly tomato yields were derived into equations to predict yields for future growing seasons. An empirical model cumulating 3, 6, and 9 weeks of light and temperature data was developed to predict yields 4 weeks ahead of time with a RMSE of 0.45 kg/m2. When one-week-ahead predictions from the Agassiz expert system model were compared with actual recorded yields a RMSE of 0.401 kg/m2 was calculated. The expert system model utilizing trend recognition techniques was also used as a comparison with the two math models. When compared and ranked for prediction accuracy, application flexibility, and user-friendliness, the expert system was chosen as the overall best model for tomato yield prediction.
Item Metadata
Title |
The prediction and validation of greenhouse tomato yield using mathematical models and expert systems
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1995
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Description |
Greenhouse tomato yields were predicted using two mathematical models
developed in this study - the empirical and deterministic models. Weekly yield predictions
for an entire growing season were compared with actual yields and results from an expert
system model developed by the Agassiz Research Station.
The deterministic math model involved using first principle equations of photosynthesis
and respiration to simulate crop growth. Utilizing a known tomato yield conversion factor,
net photosynthesis rates (Pnet) were converted to weekly yield predictions and compared
with actual recorded yields. A deterministic model using two week cumulations of Pnet
converted to yield was used successfully to predict actual tomato yields 6 weeks ahead of
time with a root-mean-square-error (RMSE) of 0.38 kg/m2.
The empirical math model employed regression techniques to fit historical greenhouse
climate data to recorded yields. Correlations between light, temperature, and weekly
tomato yields were derived into equations to predict yields for future growing seasons. An
empirical model cumulating 3, 6, and 9 weeks of light and temperature data was developed
to predict yields 4 weeks ahead of time with a RMSE of 0.45 kg/m2.
When one-week-ahead predictions from the Agassiz expert system model were
compared with actual recorded yields a RMSE of 0.401 kg/m2 was calculated. The expert
system model utilizing trend recognition techniques was also used as a comparison with the
two math models. When compared and ranked for prediction accuracy, application
flexibility, and user-friendliness, the expert system was chosen as the overall best model for
tomato yield prediction.
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Extent |
9451978 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-01-15
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0058533
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1995-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.