LAI reached during simulation is too low

[Georg]

I am modeling poplar and wheat for a river catchment in central
Germany. The aim of the work is to compare the water balance effects
of the two species. I got the simulation set up and the water balance
adds up just fine. The problem is, my LAI time series do not look
good. I don't know why, but for some reason I just never reach my BLAI
(maximum LAI) specified in my crop.dat. Both, wheat and poplar reach a
maximum LAI of around 2 in my simulation, eventough BLAI=4 is for
wheat and BLAI=5.5 is for poplar. I played with PHU (potential heat
units do maturity) and the other LAI effecting parameters in the
crop.dat, but just cannot achieve the desired effect. Does anyone know
what could be the reason for my low LAIs?

Thanks,

Georg

[cibin]

Low LAI values may be due to stresses- nutrients or water.. check
nutrient stress numbers..

Cibin

[Georg]

Hi Cibin,

thanks for yours reply. I had indeed a problem with water stress. I
solved this problem and now I can potentially reach high LAI values
(if I set BLAI high enough). Though, using the LAI that I assume to be
reasonable for my crop (winter wheat BLAI=4), I never reach the
maximum LAI during the growing season. All I get is a LAI of about 90%
(3.4) of the BLAI. Stress does not play a role anymore. The growing
season is long enough (I tried different length and always end up with
the same problem). Do you have any further suggestions how to reach
the maximum LAI?

Georg

[cibin]

other factors affecting could be radiation use efficiency (BIO_E) and
heat units to maturity. Even other parameters in growth curve as LAI
at different stages can have a role in reaching LAI to BLAI.

Cibin