Plant density

[Baya]

Hi,
I just have two short questions. Is there a way for modifying the
plant density/ha in Daisy? And how can the default value be viewed?
I'd appreciate any help.
Thanks Baya

[Per Abrahamsen]

On Tue, Jan 26, 2010 at 4:28 PM, Baya <beyer.m...@googlemail.com> wrote:

I just have two short questions. Is there a way for modifying the
plant density/ha in Daisy? And how can the default value be viewed?

Not really.  Initial growth is (mostly) governed by the DSLAI05 parameter, which can be found in the individual crop files (like potato.dai).

We have a new model that allows you directly to specify the seed density, but we have not any crop parameterizations for the new model yet.   You can read about it here:

  http://code.google.com/p/daisy-model/wiki/Daisy436

Regards,

Per

[Baya]

Thanks for that quick answer!

In our experiment, we were planting Pioneer Maize. The default value
for DSLAI05 is 0,13. Due to the fact that decreasing leads to higher
yields I guess this means higher plant density. However, is it
possible to estimate a quantity in plants/ha based on the DSLAI05 or
other parameters?

Also, I already read about the new model which includes seed density.
I do know the weight of seeds per m². Unfortunately, I don't know
about the other parameters that have to be specified, like Carbon
release per day, water content per seed or C and N fraction. I guess
thats also what you mean with you don't have parametrizations for
crops yet. Is it possible to just use that one line in the setup file
to realize higher plant density?:

(sow ("Pioneer Maize; Seed" (weight 47.62 [g w.w./ha]))) ?

[Baya]

[Per Abrahamsen]

Daisy never really model individual plants, not even with the new seed model, so finding plant density from Daisy parameters alone is not possible.

But if you know the leaf area of a single plant at stage where half the soil surface is covered by plant leaves (DSLAI05), you can "calculate backwards" to find the number of plants.  For low values of LAI, LAI is approximately equal to "number of plants per soil area" times "leaf area per plant".

No, specifying seed weight without the other seed parameters will not do anything good.  But you can find water, C and N content of Maize by searching the literature.  That leaves only the release rate, which you will have to fit to your data, or to someone elses data, if you can find a dataset that contain both seed weight and early measuments of LAI.

Regards,

Per

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