Hallo Harikrishna
Regarding P2, because the photoperiod is less than 12.5 hr during the
cropping period, P2 will have no influence on the simulation. For your study
use a P2 value of 0 for your study. A word of caution if you start using
this particular cultivar in areas where the photoperiod exceed 12.5 hours
you need to recalibrate for P2.

As you have indicated you already have run sensitivity analysis, how much
difference is their between the simulated and measured yields if  both the
nitrogen and water simulations is turn off. Then turn the water simulation
on and the nitrogen simulation off and repeat the process. This will give
you an indication why the predictive yield is lower than the measured
yields. With both water an N simulation turned on look at the N and water
stress indicators in overview.out, this will also indicate where the problem
is.

Hope this help

Regards
Andre

-----Original Message-----
From: natp gsdas [mailto:[log in to unmask]]
Sent: Monday, March 03, 2003 4:35 AM
To: [log in to unmask]
Subject:


Sir I am Mr.Harikrishna B.L. Ph.D. Scholar in the Dept. of Soil Science &
Agril. Chemistry at UAS-Dharwad,  Karnataka. Sir I am working on maize crop
simulation modeling.

1.      My research title is "studies on effect of soil depths, nitrogen
doses and their splits on growth and yield of maize crop using CERES maize
model". I have taken two season maize crop and collected detailed
information about soil profiles (shallow depth-44cm, medium depth-75cm and
deep black-150cm), maximum & minimum temperature, sunshine hours, maxi.
number of kernels per/cob, average grain filling rate (mg/day), flowering
date for the calculation of  genetic-coefficients (G.C) for my crops. Sir
one of the parameter required for G.C is P2 parameter (Extent to which
development (expressed in days) is delayed for each hour increase in
photoperiod above the longest photoperiod at which development proceeds at a
maximum rate (which is considered as 12.5 hr.) sir I don't know how to
calculate this parameter. Sir I am sending weather data of my expt., if time
permits please calculate the G.C for my crop including P2 parameter,
otherwise send me the stepwise detailed procedure about how to calculate
this G.C.
2.      Sir I have used shallow soil profile (44cm deep) in that I got 5603
kg grains/ha measured yield but when I simulated using the same treatment
,the predicted grain yield was 4600 kg/ha,and lower no. of kernels per cob,
even I calibrated the genetic coefficent parameters under sensitivity
analysis , please suggest me that how to over come this problem or send me
the correct information regarding this problem.


Measured data of my crop are as follows
Crop: maize
Flowering date: 58 days
Maxi. Kernels: 725/ cob
Grain filling rate: 6.7 mg/day
Sun shine hour: below 11hr. /day during entire cropping period.



Thanking you
Harikrishna