Dear listers
There is a good question from Traore, Seydou <[log in to unmask]> in
a course by Univ of Nebraska on Plant Organisation and Computer
Simulation Models going on at present. I post the question in original
for this group to comment.
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The original question:
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I would like to have more details on each genetic coefficient, or have
some reference (articles pdf files) detailing them. For example, in the
DSSAT series of crop models, the genetic coefficients are not defined
in the same way for different crops, even for crop in the same group
like cereals.
If I take the example of millet in DSSAT4, we have
P1 : Thermal time from seedling emergence to the end of the juvenile
phase (expressed in degree days above a base temperature of 10øC)
during which the plant is not responsive to changes in photoperiod.
P20 : Critical photoperiod or the longest day length (in hours) at
which development occurs at a maximum rate. At values greater than P20,
the rate of development is reduced.
P2R : Extent to which phasic development leading to panicle initiation
(expressed in degree days) is delayed for each hour increase in
photoperiod above P20.
P5 : Thermal time (degree days above a base temperature of 10øC) from
beginning of grain filling (3-4 days after flowering) to physiological
maturity.
G1 : Scaler for relative leaf size.
G4 : Scaler for partitioning of assimilates to the panicle (head).
PHINT : Phylochron interval; the interval in thermal time (degree days)
between successive leaf tip appearances.
What is the end of juvenile phase that determines the calculation of
P1 ?
What is panicle initiation mentioned in the definition of P2R ? Is it
different from the end of juvenile phase ?
What coefficient accounts for the thermal time between panicle
initiation and the beginning of grain filling, since P2R stops at
panicle initiation and P5 starts 3-4 after flowering ?
I have a particular interest in the photoperiod sensitivity
coefficients, but in DSSAT 4, it is defined differently for wheat,
maize and millet. Is it possible to have a unique definition of these
coefficients?
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Thanks,
Dr Dharam Singh Dabas, Professor of Soil Science,
CCS Haryana Agricultural University, Hisar 125004
Ph: 01662-224163 and +919416532650
E-mail: [log in to unmask]
----- Original Message -----
From: xiongw <[log in to unmask]>
Date: Friday, November 18, 2005 6:39 am
Subject: Re: new wheat gen. coefficients
> Dear Gerrit
>
> In DSSAT4, the coefficiencts used in the CSM-Cropsim-Ceres model
> differ from those used in DSSAT version 3.5, is the change occured
> for all cereal crops or just for some given crops, e.g. wheat. I
> used the version 3.5 rice coefficients in DSSAT 4, but there is no
> problem.
> Thanks.
> ----- Original Message -----
> From: "Gerrit Hoogenboom" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, July 21, 2005 4:37 AM
> Subject: Re: new wheat gen. coefficients
>
>
> >! Coefficients used in the CSM-Cropsim-Ceres model differ from
> those used
> > ! in DSSAT Version 3.5. They can be calculated (approximately) from
> > ! V3.5 coefficients as follows:
> >
> > ! P1V = P1V(v3.5)*10
> > ! P1D = P1D(V3.5)*20
> > ! P5 = P5(V3.5)*20 + 430
> > ! G1 = G1(V3.5)*5 + 5
> > ! G2 = (G2(V3.5)*0.35+0.65) * P5/20
> > ! G3 = G3(V3.5)*0.7
> > ! PHINT = PHINT(V3.5)
> >
> >
> >
> > At 12:47 PM 07/20/2005, you wrote:
> >>Dear all,
> >>
> >>I cant use any of the wheat cultivars wich are already in
> version 4,
> >>as they aren' t for durum wheat. So I found genetic coefficients for
> >>others wheat varieties and I tried to import them from WHCER040.CUL
> >>by hand, but doesn' t work.
> >>Is there any way to import them, maybe with use of GenCalc tool from
> >>an earlier version of DSSAT ?
> >>I have no experimental data for these varieties.
> >>
> >>
> >>Regards,
> >>
> >>Mary Vitaliotou
> >
>
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