Dear Wendy:

Practically I can't give you any help, except as to reasoning the problem
for you and others. I have seen some answers to your request and they are
all true and valid. I haven't version 4.0 so it makes my advice harder to
express in clear terms. But it seems to me that there are answers to some of
your questions which I haven't seen. Let's recapitulate:

First: It's there a GenCalc facility in DSSAT 4.0
Answer: I don't know
You should obtain an answer to that question.

Second: Are the scarce data you have about DT84 soybean cultivar AND
agrometeorological daily data available to you, enough to make a reliable
estimate of genetic coefficients of DT84 cultivar. Even if v4 had a GenCalc
tool or using instead an earlier version of DSSAT?
Answer: I don't know
You should obtain an answer to that question

If somebody gives you those answers you will able to decide what to do and
you'll be on your way.
In particular it is not clear to me how to understand that DT84 is not very
photoperiod sensitive and how many crop cycles of data you have for
estimation of genetic coefficients, meaning that I don't know if you have
data enough to capture climate variability even on one site (in Cambodia) so
to make a reliable estimation of genetic coefficients.

If I were you I would be beginning by running all available cultivars on
your v4 with the same data you have (this can be done in no time at all),
and compare with experimental results at hand. This would allows you to
select some available cultivar that express affinity to your DT84.

Then I would use a GenCalc facility (if there is one) guided by that
previous computer experiment. If I had  no GenCalc facility I would do it by
hand. You could say that you would be using a trial and error method.

What other colleagues had answered you about how stable and reliable are
genetic coefficients as to different environmental conditions is true. You
could get all messages in that discussion from the server, but if it is not
possible, I would gladly send you my copies of it through e-mail.

Sincerely yours,

Roger E. Rivero Vega
----- Original Message -----
From: "Wendy Vance" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, May 17, 2005 9:56 PM
Subject: FW: Choosing a soybean cultivar and genetic coefficients


> Dear Listers
>
> I have just started using DSSAT (v4).  I am attempting to model soybean
> production in Cambodia.  I am having problems choosing a cultivar to use
> in the model.  In trials currently being completed in Cambodia a variety
> called DT84 is being used. Unfortunately I am having difficulty finding
> genetic coefficients for this variety.  I was thinking of using a
> cultivar which is already in version 4, which may be a variety suitable
> for Cambodian conditions, but am having difficulty deciding if any are
> appropriate.  I was also reading papers that describe the use of Gencalc
> and thought this may be an option but this does not seem to be available
> in version 4.
>
> The information I have on variety DT84 is 1) it is not very photoperiod
> sensitive and is an early duration variety. 2)  In trials the days to
> 1st flowering is between 32-35 days, 1st podding 41 days and growth
> duration 80-86 days.
>
> My questions are
>
> 1.  Can anyone suggest a cultivar currently in V4 to use that would be
> appropriate, or how I might choose one to use?
>
> 2.  Can anyone suggest how I might best determine genetic coefficients
> for this variety?
>
>
>
> I welcome any advice you may have.
>
>
>
> Thanks in advance
>
>
>
> Wendy
>
> Wendy Vance
> Professional Officer
> School of Environmental Sciences
> Murdoch University
> WA
> email  [log in to unmask]
> Ph 08 9360 6993
>