Simulation of tropical maize genotypes with the current version of
CERES-Maize requires some care. At CIMMYT, we have been conducting
extensive field calibration experiments mainly at Tlatlizapan and
Poza Rica for a number of years with a small number of cultivars
(OPVs and hybrids). Simulation of these experiments with genotype
coefficients for temperate maizes results in serious over-estimation
of final leaf number and therefore time to anthesis. Indirectly, this
also results in over-estimation of leaf area, biomass production and
grain yield - especially at lower production levels. One way out, of
course, is to just calibrate the genotype coefficients, although I
believe that it is necessary to also alter parameters in equations,
and probably some of the equations themselves. This would lead to a
more robust model for tropical maize.
Actually, we are in the process of developing the basics of development
of tropical maize, including responses to both photoperiod and
temperature. Available time will determine progress.
 
Dr. Ortega, here are some examples of genetic coefficients that gave
me reasonable results. Matching of anthesis and maturity can be
achieved by calibration of P1 and P5. I do not guarantee you,
however, that they have real relevance to developmental events in
the field - it are just calibrated values:
 
                P1      P2      P5      G2      G3
 
PR 8330 (early) 240     0.6     970     550     8
La Posta (late) 310     0.6     980     550     8
Pool 16 (early) 220     0.6    1020     550     8
Pool 28 (int.)  310     0.6     980     550     8
late hybrid     330     0.6    1100     550     8
 
I will send you a copy of our poster presentation at the last ASA
meeting.
 
Regards,
 
Anne Elings
 
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CENTRO INTERNACIONAL DE MEJORAMIENTO DE MAIZ Y TRIGO (CIMMYT,INT)
        International Maize and Wheat Improvement Center
 
      - Sustainable Maize and Wheat Systems for the Poor -
 
   Lisboa 27  Apdo. Postal 6-641  CP 06600  Mexico, D.F. MEXICO
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