Ken,

PEST is very powerful  parameter estimation software,
http://www.pesthomepage.org/

Regards,
Jonathan

On 25/04/2011 03:11, Boote,Kenneth J wrote:
> 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
>
> ________________________________________
> 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


--
Jonathan Massheder
Simulistics Ltd
www.simulistics.com