Abstract
The purpose of this study was to evaluate the utility of wheat growth simulation models in deriving a crop specific drought index (CSDI). This new index features both the environment and the crop: transpiration; root absorption; phenological growth stages; and the climatic and soil moisture variables. Four models were chosen to predict plant features from environmental input data. Environmental and physiological data were available from the 1985 and 1986 growing seasons for winter wheat at five locations in North America ranging from Lethbridge, Canada, to Lubbock, Texas. The potential for using models to monitor drought on a regional scale was evaluated under conditions of limited input data. Model performance was compared by examining statistical indices. Measured and model-predicted values of leaf area index (LAI), tiller number, soil moisture content at all observed depths, and final yield were compared. CERES, the selected model, was then tested using a twenty-two (22) year data set of crop production and meteorological conditions at North Platte, Nebraska. Comparisons were drawn between CSDI, Palmer Drought Severity Index (PDSI), and reported crop yields at North Platte. Several model performance statistics were included in a three dimensional graphical presentation to make comparison between models relatively easy. Acceptable performance was obtained from the soil moisture analysis and the CERES model did remarkably well in leaf area index estimation. However, the performance of all models on estimated tiller numbers was unsatisfactory. The performance of some models relative to yield estimates over all locations is somewhat inflated due to clustering of the data. Coefficients of determination obtained from the 22 year analysis at North Platte were low. Without proper historical records, however, it is not possible to improve on what is perhaps the weakest link, the accuracy of inputs. The CSDI showed definite advantages over the PDSI when compared to crop performance. It was shown that small gains in model accuracy will result in large gains in CSDI accuracy. The CSDI concept can be applied to other crops via other models and therefore has greater potential for improvement and use in drought monitoring than the PDSI or Crop Moisture Index.
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Claims 8
Claim · model-written summary
The CERES model estimated leaf area index remarkably well in winter wheat.
- Taxon
- winter wheat
Triticum aestivumt0 - Outcome
- leaf area index estimatione1
- Qualifier
- remarkably welle1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“crop specific drought index for winter wheat”
e1“the CERES model did remarkably well in leaf area index estimation”
Claim · model-written summary
All models performed unsatisfactorily on estimated tiller numbers in winter wheat.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- estimated tiller numberse2
- Qualifier
- unsatisfactorye2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“crop specific drought index for winter wheat”
e2“the performance of all models on estimated tiller numbers was unsatisfactory”
Claim · model-written summary
Soil moisture analysis gave acceptable model performance in winter wheat.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- soil moisture analysise3
- Qualifier
- Acceptable performancee3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“crop specific drought index for winter wheat”
e3“Acceptable performance was obtained from the soil moisture analysis”
Claim · model-written summary
The CSDI showed definite advantages over PDSI when compared to crop performance.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- crop performancee4
- Qualifier
- definite advantagese4
- Comparator
- PDSIe4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“crop specific drought index for winter wheat”
e4“The CSDI showed definite advantages over the PDSI when compared to crop performance”
Claim · model-written summary
Small gains in model accuracy result in larger gains in CSDI accuracy for winter wheat.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- small gains in model accuracye5
- Outcome
- CSDI accuracye5
- Direction
- increaseinferrede5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“crop specific drought index for winter wheat”
e5“It was shown that small gains in model accuracy will result in large gains in CSDI accuracy”
Claim · model-written summary
Coefficients of determination from the 22 year analysis at North Platte were low.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- Coefficients of determinatione6
- Qualifier
- 22 year analysise6
- Setting
- North Plattee6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“crop specific drought index for winter wheat”
e6“Coefficients of determination obtained from the 22 year analysis at North Platte were low”
Claim · model-written summary
Relative yield performance of some models is somewhat inflated by clustering of the data.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- performance of some models relative to yield estimatese7
- Qualifier
- inflated due to clustering of the datae7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“crop specific drought index for winter wheat”
e7“The performance of some models relative to yield estimates over all locations is somewhat inflated due to clustering of the data”
Claim · model-written summary
The CSDI concept can be applied to other crops and has greater potential than PDSI or Crop Moisture Index for drought monitoring.
- Taxon
- winter wheatTriticum aestivumt0
- Outcome
- potential for improvement and use in drought monitoringe1
- Qualifier
- applied to other cropse1
- Comparator
- PDSI or Crop Moisture Indexe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“crop specific drought index for winter wheat”
e1“The CSDI concept can be applied to other crops via other models and therefore has greater potential for improvement and use in drought monitoring than the PDSI or Crop Moisture Index”