DRATES

Exercise objective:

·    Calibrating the development rate.

Suggested reading:

Chapters 3.2.1, 7.3 and 8.2 of the book ORYZA2000: Modeling lowland rice.

A special program is available to compute the development rate parameters from the observed phenological data in the experimental data file: DRATES.EXE. Though this program uses the same input data files as ORYZA2000, it does not run under the FSEWin shell.

Exercises:

Ex-VI.2. Click away the Shell (don’t close it, just ‘hide it’!) and open a file manager under Windows (e.g., Windows Explorer or ‘My Computer’ or a DOS Box). Find the directory C:\COURSE\PARAM\ and study its contents.

In C:\COURSE\PARAM\, we note the presence of the files DRATES.EXE and PARAM.IN. The file PARAM.IN functions in the same way as the file CONTROL.DAT. We can read and edit these files using any text processor (such as Notepad) or use our FSEWin Shell to do that. In these exercises, we will use the FSEWin Shell to read and edit the input and output data files of DRATES (and of the program PARAM, see the exercises ‘The PARAM program’ below). In ‘Exercise Troubleshooting’ (see below), we will use other text processors to edit data files.

Ex-VI.3. Click away (don’t close) the file manager and go back to the FSEWinRunOnly Shell. Click the pull down menu ‘File’ in the menu bar in the left-hand top of the window, and select ‘Add Input Data File’. In the box ‘Files of Type’, select ‘All Files (*,*)’. We now see all files available in the directory C:\COURSE\PARAM\ (if the box opens in another directory/folder, scroll through your computer until you find it). Select the file ‘PARAM.IN’, and click the button ‘open’. Note that the file PARAM.IN is now available for viewing and editing under ‘Input Datafiles’ in the list of files on the left-hand side of the window of the FSEWin Shell. View PARAM.IN and verify its contents:

FILEOP = 'PARAM.OUT'      ! Parameter output file

FILEOR = 'DRATE.OUT'      ! Development rate output file

FILEOL = 'MODEL.LOG'      ! Log file

FILEIR = ' '

FILEIT = 'C:\COURSE\PARAM\MANAGE.TST'    ! Experimental data

FILEI1 = 'C:\COURSE\PARAM\JD305.DAT'     ! Crop data

The structure of PARAM.IN is the same as that of CONTROL.DAT. Note in the header that PARAM.IN serves as control file for both the programs DRATES and PARAM. The file name specified under FILEOP (PARAM.OUT) will contain the output results of the program PARAM, whereas the file name specified under FILEOR (DRATE.OUT) will contain the output results of the program DRATES. Both these file names can be changed by the user. As in the file CONTROL.DAT, the experimental data file is specified under FILEIT and the crop data file under FILEI1. The program DRATES reads only the experimental data file (here MANAGE.TST), and uses the weather data and the observed phenological development dates to calculate the development rate parameters.

Ex-VI.4. Click away the Shell (don’t close it, just minimize it) and run the program DRATES.EXE using your file manager. Ignore the error message ‘ERROR in OPSYS: no data for output file’ and just give a return. Go back to the FSEWin Shell, and include the file DRATE.OUT following the same instructions as given in exercise VI.3. Open DRATE.OUT and find the computed development rates:

DVRJ  = .000419

DVRI  = .000758

DVRP  = .000586

DVRR  = .002154

Except for DVRR, these computed development rates for JD305 are lower than those for IR72, which agrees with the observation that the crop growth duration was longer for JD305 than for IR72.

Ex-VI.5. Open the file JD305.DAT and change the development rate parameters to the ones computed with DRATES (see above). Run ORYZA2000, open the data output file Run 1 (this is the run using the file JD305.DAT) and find the dates for panicle initiation, flowering and maturity. Next, make graphs of simulated and measured LAI, WAGT, WSO, WLVG and any other variable of your choice versus time. Comment on the difference between simulated and measured values, and on the differences between Run 0 and Run 1.

Using the new development rates in JD305.DAT, the simulated dates of panicle initiation, flowering and maturity now match the observed ones as given in the experimental data file MANAGE.TST (Run 1). In Figure VI.2, we now see that a complete cycle of LAI and the other crop variables is simulated, and Run1 does a much better job than Run0 (with IR72 development rates). The weights of the total above-ground biomass (Figure VI.2c) and the storage organs (Figure VI.2d) are simulated pretty well. However, the simulation of LAI and of dry weight of green leaves considerable overestimates measured values, Figure VI.2a and Figure VI.2b, respectively. Note the similarity in shape of the curves in Figures VI.2a and VI.2b: in ORYZA2000, there is a fixed relationship between the area and the weight of the leaves after the exponential phase of growth (Chapter 3.2.9 of the book ‘ORYZA2000: modeling lowland rice’). So, now we have to calibrate other crop parameters, to improve the simulation, especially in relation to the development and growth of leaves.

Figure VI.2a. Simulated and measured leaf area index (LAI; -); cv. JD305, Beijing, 1987; after calibration of development rates.

Figure VI.2b. Simulated and measured dry weights (kg ha-1) of green leaves (WLVG); cv. JD305, Beijing, 1987; after calibration of development rates.

Figure VI.2c. Simulated and measured dry weights (kg ha-1) of total above-ground biomass (WAGT); cv. JD305, Beijing, 1987; after calibration of development rates.

Figure VI.2d. Simulated and measured dry weights (kg ha-1) of storage organs (WSO); cv. JD305, Beijing, 1987; after calibration of development rates.