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Respiration

Maintenance respiration is calculated for the photo period and for darkness using AGROSIM algorithms (Mirschel und Wenkel, 2007):

\[M_{photo} = \sum (W_i \cdot m_i) \cdot 2^{a\cdot(T_{photo} - b)} \cdot (2-L_N)\]
\[M_{dark} = \sum (W_i \cdot m_i) \cdot 2^{a\cdot(T_{dark} - b)} \cdot L_N\]

\(M_{photo}\) Maintenance respiration during the photo period \([Pa]\)
\(M_{dark}\) Maintenance respiration in darkness \([Pa]\)
\(W_i\) Dry mass of organ \(i\) \([kg \, m^{-2}]\)
\(m_i\) Specific maintenance respiration of organ \(i\) \([kg \, m^{-2}]\)
\(T_{photo}\) Mean temperature during the photo period \([^{\circ} C]\)
\(T_{dark}\) Mean temperature during the dark period \([^{\circ} C]\)
\(a, b\) Parameters
\(L_N\) Normalised day length \([d]\)

where

\[L_N = 2 - \left ( \frac{L_p}{12} \right )\]

\(L_N\) Normalised day length \([d]\)
\(L_P\) Photoactive day length \([d]\)

and

\[T_{photo} = T_{max} - \left ( \frac{T_{max} - T_{min}} {4} \right )\]
\[T_{dark} = T_{min} + \left ( \frac{T_{max} - T_{min}} {4} \right )\]

\(T_{photo}\) Mean temperature during the photo period \([^{\circ} C]\)
\(T_{max}\) Daily maximum air temperature \([^{\circ} C]\)
\(T_{min}\) Daily minimum air temperature \([^{\circ} C]\)

Growth respiration is calculated accordingly.

Maintenance respiration is served with priority using assimilates produced by photosynthesis; growth respiration is second in line. Assimilates are assigned to the crop organs according to a partitioning matrix which is organised by the crop’s developmental stages. The crop's development, in turn, is calculated from the sum of degree days and, if applicable, modified for each stage by day length and vernalisation requirement.

Reference

  • Mirschel, W. und K.-O. Wenkel (2007): Modelling soil-crop interactions with AGROSIM model family. In: K.C. Kersebaum, J.-M. Hecker, W. Mirschel und M. Wegehenkel (Hrsg.), Modelling water and nutrient dynamics in soil crop systems. Springer, Stuttgart, 59-74.