Hello Luis,
   In the equation that calculates XTN, you have the quantity (-BF+CUMPH)
below. The quantity should be (-BF*CUMPH) instead. So, at CUMPH = 1, XTN =
-8.58.
   Also, remember that the value of XTN is also a function of CUMPH, so it
will have to vary with CUMPH as well as MPLAG. This might take care of the
descending area value as the leaf number (CUMPH) increases.
   I hope this helps.
Sincerely,
Richard

At 07:17 PM 05/21/2003 -0700, you wrote:
> Dear Dr. Richard Ogoshi and modellers:
>Thanks a lot for your help trying to solve MPLAG in CERES-rice. I have
been trying to solve this equation but could´t get satisfactory results.
>I began with the first leaf so CUMPH=1, and followed
>CUMPH   BF      CUMPH-BF        XTN     DTT     PHINT   PC      TI      MPLAG
>1       0.12    0.88    -23.33  19.2    83      0.728   0.3177  2.49E-7
>1.3177  0.12    1.1977  -32.06  19.1    83      0.7496  0.3070  4.06E-11
>1.6247  0.12    1.5047  -43.58  19.05   83      0.7705  0.2979  4.32E-16
>XTN= -9.678*EXP(-BF+CUMPH)
>PC = 0.66 + 0.068 * CUMPH
>TI = DTT / (PHINT * PC)
>MPLAG = A / CUMPH * (-BF) * XTN * EXP(XTN) * TI   without stress
>A= 3800
>MPLAG: daily growth of leaf area per plant (cm2/plant) is decreasing when
the number of leaves is growing up, I think that there must be something
wrong here, but I can´t detect it.
>I have a plant population of 337,9 emerged plants per m2.
>When calculating how simple leaf area varies with leaf number, I got this:
>CUMPH   A/CUMPH*(-BF)*XTN*EXP(XTN)
>1       7,85E-7
>1.3177  1.323215E-10
>1.6247  1.448522E-13
>I found the when the number of leaves is going up, the leaf area descends.
>What is your opinion?. I will be appreciated.
>Is BF the previous day leaf area or previous day leaf number?
>Sincerely yours:
>Luis E. Alvarez L.
>Universidad Ezequiel Zamora. UNELLEZ.
>Guanare. Estado Portuguesa. Venezuela.
>