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Reply To: | Boote,Kenneth J |
Date: | Sun, 24 Apr 2011 22:11:11 -0400 |
Content-Type: | text/plain |
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Behnam:
What is PEST? I don't know what that is?
You should not change any Ecotype parameters. It would be dangerous to calibrate RUE (which is in the Ecotype file), as that is viewed as a constant across all maize hybrids. The only exception is for a low RUE for pure inbred lines used in plant breeder plots (and that is not something you are looking at). If you see a value for RUE of 4.5 in ecotype file, that is not a good number and will disappear by the time of release of V4.5 DSSAT.
The principle is that you should calibrate genetic coefficients only for the optimum irrigation (and N fertilization) treatments. That way, any failure to predict accurately the growth and yield at low irrigation or low N fertilization indicates a problem with the prediction (and inputs) related to water and N balance. So, yes, the genetic coefficients will change if you optimize them with all the treatments being considered (as you already say you observed).
Good luck.
Ken Boote
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From: DSSAT - Crop Models and Applications [[log in to unmask]] On Behalf Of Behnam [[log in to unmask]]
Sent: Sunday, April 24, 2011 3:44 AM
To: [log in to unmask]
Subject: Does the irrigation regime affect the crop parameters while calibration?
Dear users,
I am using PEST to calibrate cultivar parameters of MAIZE.
1) Do I have to change any Ecotype parameters in this process? By
default, there are only 2 Ecotypes in DSSAT database.
2) Is it true if I find cultivar parameters different for different
irrigation treatments? When I used all irrigation treatments, the
calibration results got worst in comparison to the time I used only 1
or 2 irrigation treatments.
Best
Behnam
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