Toolbox: plant

Plant growth, reproduction: 6 reserves, 2 structures, generalized morphology


Demo that runs: The model accounts for: effects of light (J_L.F), dioxygen (X_O) and carbon dioxide (X_C) concentrations in the air, ammonium (X_NH), nitrate (X_NO) and water (X_H) concentrations in the soil, and temperature (T). These environmental parameters are taken to be constant in the present implementation, but it is not difficult to let them vary in time.

Control vector:
X = [J_L.F, X_C, X_O, X_NH, X_NO, X_H, T]

The plant is decomposed in: shoot product (PS, e.g. wood), structure (VS), general reserves (ES), nitrogen-reserves (ENS) and carbon-reserves (ECS)
root product (PR, e.g. wood), structure (VR), general reserves (ER), nitrogen-reserves (ENR) and carbon-reserves (ECR)
State vector:

The plant develops through an embryonic, juvenile and adult phase
No assimilation occurs during the embryonic phase
No reproduction allocation occurs during the juvenile phase

The interaction between root and shoot resembles that between host and symbiont. It differs by translocation of general reserves, and the occurrence of the ratio of shoot and root surface area's in the saturation constants for nutrients and water.

Uptake is proportional to surface area of root or shoot. The area's are take to be functions of the structure, and specified in routine flux; many plants develop from a V1-morph, via a isomorph, to a V0-morph. Maintenance of root and shoot is proportional to their structure.

The effect of water is incorporated with a single parameter for water availability. This is too simple, since what counts is water transport, which depends on water in the soil as well as relative humidity in the atmosphere. The saturation constant depends on the ratio if the surface area's of shoot and root (see DEB-book page {155}); evaporation through shoots surface area, and uptake through roots surface area are in control of water transport.

The effect of both ammonia and nitrate are implemented, since their relative abundance dominates the preference of the plant. Observe that, for suitable parameter choices, the shoot/root ratio depends on environmental conditions such that adverse conditions are compensated, to some extend. No optimality criteria are incorporated; just plain DEB mechanisms (see DEB-book page {209}). Aging is not implemented.

Example of use after (optionally) editing file pars_plant.m: plant


Set the parameters by editing file pars_plant.m in toolbox plant.


The plant is exposed to a constant environment.
Being usually below ground, the values for roots have been made negative, and the zero-line is plotted in brown. See pages {207} ff of the DEB-book.
Four plots are shown of variables against time

Fig 1 Structure of shoot (green) and root (red)

Fig 2 Product of shoot (green) and root (red); you can think of wood, for instance

Fig 3 Reserves of shoot and root; general reserve (red), C-reserve (brown), N-reserve (blue)

Fig 4 Reserve densities of shoot and root (= reserve per structure); general reserve (red), C-reserve (brown), N-reserve (blue). The general reserve density of the root is clipped to the maximum value of the other reserve densities. This is done because the seed initially starts with general root reserves only, which means that the general root reserve density is infinitely large.

Example of use after editing file pars_plant.m in toolbox plant: pars_plant;shtime_plant. The command pars_plant;shtime_plant(2) gives figure 2 only.

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