Hi Jeff,

Many thanks for your prompt response. I'm using DSSAT ver 3.5.  In South
Africa we have 3 main areas where wheat are cultivated.

1) Being Cape or South Africa during the winter (Planting starts in
May). IE Winter Wheat
2) Then we have Eastern Freestate (where planting is a little bit later
July/Aug) IE: Spring Wheat
3) We also have the Norther Freestate area and Natal. Spring Wheat.

Should u have parameters for Limpopo it would be great:

Other cultivar are Eland,Beta,Caledon,Carnia,PAN,SST etc

a) P1V = Days at optimum vernalizing temperature required to complete
vernalization.
b) P1D = Percentage reduction in development rate in a photoperiod 10
hour shorter than the optimum relative to that at the optimum
c) P5 = Grain filling (excluding lag) period duration (oC.d)
d) G1 = Kernel number per unit canopy weight at anthesis (1/g).
e) G2 = Standard kernel size under optimum conditions (mg). Related to
kernel filling rate (G2,mg/d), which used internally, as follows:
f) G2 = G2WT/P5 * 20.0, where 20.0=deg.d in a standard day
g) G3 = Standard, non-stressed dry weight (total,including grain) of a
single tiller at maturity (g).
h) PHINT Phylochron interval; = the interval in thermal time (degree
days) between successive leaf tip appearances.


Many thanks.

Hope to hear from u soon


-----Original Message-----
From: DSSAT - Crop Models and Applications
[mailto:[log in to unmask]] On Behalf Of Jeffrey White
Sent: 28 January 2005 05:26 PM
To: [log in to unmask]
Subject: Re: Winter wheat - cultivars for RSA

Hello Micheal,

While I do not have genetic coefficients for the five wheat cultivars
you
list, I have a few comments that may be of interest to other modelers:

1.  There now are probably three versions of wheat models that run from
DSSAT.  For any request relating to specific crop or modeling issue, it
will help to indicate the version being used.  In the latest versions of
DSSAT, the OVERVIEW.OUT file lists the model version in the header of
each
run.  For example:
*SIMULATION OVERVIEW FILE

*DSSAT Cropping System Model Ver. 4.0.1.000               Jan 26, 2005;
14:58:30

2.  Your e-mail subject line mentions "winter wheat."  For southern
Africa, aren't you actually growing wheats with a spring growth habit
but
planted in the fall/winter (May to July in the Southern Hemisphere)?
This
is a very common source of confusion.  For initial modeling, you should
definitely use a spring wheat cultivar with the vernalization and
photoperiod requirements set low (but not necessarily to 0).

3. One option for deducing cultivar coefficients might be through more
widely known cultivars that are parents or sister lines of these
cultivars.  Unfortunately, of the five you list, the only cultivar whose
pedigree I could find is Limpopo.  The Global Wheat Information System
shows Limpopo as having Tokwe as the paternal source, and Sonora 64 as
one
grandparent on the maternal side:
http://mendel.lafs.uq.edu.au/cgi-bin/Germplasm.pl?name=limpopo

4. Your very reasonable, practical query shows precisely why we need to
push for a system that allows users to determine cultivar-specific
coefficietns through actual crop genotypes.  A typical spring bread
wheat
will have the dominant alleles at one to three of the Vrn1 loci.  The
line
also may vary in earliness per se (Eps loci), dwarfing loci (Rht) and
photoperiod (Ppd).  The exact genotype of a given cultivar might be
inferred from pedigree records or diagnosed with molecular probes
(apparently available already for the Vrn and Rht loci).  Markus Herndl
posted a query on gene-based wheat models, and I would be curious to
hear
other people's ideas for  wheat or any other crop.

5.  Do you have any data you can share or field performance?  I would be
glad to try to calibrate these for you.  I do have limited data on Tokwe
and Sonora 64 using DSSAT CSM 4.0

Best regards,
Jeff White

USWCL, USDA-ARS
Phoenix, AZ 85040
Tel. 1-602-437-1702 x 268
Fax 1-602-437-5291




Micheal Howard <[log in to unmask]>
Sent by: DSSAT - Crop Models and Applications <[log in to unmask]>
01/28/2005 04:45 AM
Please respond to
DSSAT - Crop Models and Applications <[log in to unmask]>


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Subject
Winter wheat - cultivars for RSA






Hi everybody,



Could anyone please let me know if genetic coefficients for wheat
cultivars like (Elands, Caledon,Gariep, Betta DN and Limpopo). This is
for South Africa.

Thanks

Micheal Howard

Agrista

Visible communication.

http://www.agrista.com

PO Box 211165, Bluff, South Africa, 4036

43 Sormany Rd, Brighton Beach, Durban, 4052

e-Mail: [log in to unmask]

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