The lack of genetic coefficients are still a limiting factor in
using the DSSAT models. As part of the Highveld
Ecoregional project , support by the Ecoregional fund, we
continuously searching for new methods to solve this limiting
factor. With the support of the  Protein Research Trust we
embarked on process of calculating  at least 20 of South
Africa's soya cultivars genetic coefficients from the national
soya cultivar evaluation trials.

For each cultivar we have 80 yield points represent trials at
different sites and seasons. Using only the yields we
calculated the genetic coefficients, minimizing the difference
between the simulated and observed yields. We
incorporated  Nelder &  Meads simplexs methodology into
the  software to do the minimizing.  It take us around 12
hours computer time to generate a set of genetic
coefficients.

Have somebody done similar work on calculating the
Genetic Coefficients from the national cultivar evaluation
trials?

Regards
Andre

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* ANDRE DU TOIT                      *
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