Calculation of DSRate1, 2, TempEff1, 2, PhotEff1

[Ku He]

Dear all,

I always have problems calculating some parameters. The manual is often too imprecise. For example DSRate 1 and 2. After the reference manual is the formula [DS/d] and d is the number of days between germination to flowering and flowering to maturity. For winter wheat, the distance between germination and flowering is about 240 days. This means a DSRate1 of 0.004, but the default value is 0.026. With a DSRate of 0.004, very low yields are calculated.
Is there an error in my calculation after the tutorial?

I heard that there is a correction factor with  TempEff1, 2, PhotEff1.

Where I could find more details of these parameters listed above.

I would be very grateful for an answer.

I need a complete explanation for these values.

Greetings

K.H.

[Kiril Manevski]

Hi Ku,

As you wrote, DSRate1 = 1/(days between emergence and flowering). But winter wheat vernalizes (sleeps in winter), so probably that's why you get very low DSRate1 value when you use the above equation.

I agree with you, it's not always easy to get information how some simple processes are simulated with Daisy. You can take a look in the src folder, e.g., file crop_sold.C, lines 1182-1196 for how DSRate1 is affected by temperature and daylenght and how vernalization is included. I'm not a programmer, so not always easy to read the files, but for many things the answers are explicit. For more simplistic description, take a look on p.36 in the attached doc (available online somewhere...).

Really hope answer helps a bit,

Best regards,

Kiril

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[Merete Elisabeth Styczen]

Dear Kurt Heil

I am enclosing a document that is ”work in progress”, but contains a description of the relationships you are asking for. It also includes a description of the effect of vernalisation on the development rate of winter crops. I am also enclosing an article by Wang et al., that includes quantification of the temperature function for winter wheat, as an example. You can see examples of the temperature and photoperiod functions in e.g. the winter wheat file.

 

I hope it helps clarifying the issues you have.

Best wishes

Merete Styczen

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