-> About this Resource
Scope *______
Map *____

-> Preliminary Courses
Contents & Objectives *__________________
Map *____
-> Botany
Contents & Objectives *__________________
Map *____
-> Axis Typology Patterns
Typology basis *___________
Pictograms *_________
Sexuality & development *___________________
Growth *______
Branching rhythms *______________
Branching delays *_____________
Branching positional *________________
Branching arrangement *__________________
Axis orientation *_____________
Architectural models *________________
-> Architectural Unit
About Arc. Models *______________
Models limitations *______________
Architectural Units *______________
Reiteration *_________
Sequence of development *___________________
Morphogenetic gradients *___________________
Physiological age *_____________
-> An Example
Wild Cherry (young) *_______________
Wild Cherry (adult) *______________
Wild Cherry (mature) *________________
Quiz *____
Case study Quiz *_____________
Supplementary resources *____________________

-> Eco-Physiology
Contents & Objectives *__________________
Map *____
-> Growth Factors
Factors affecting Growth *___________________
Endogenous Processes *_________________
Environmental Factors *_________________
Thermal Time *___________
-> Light interaction
P.A.R. *_____
Light absorption *_____________
Photosynthesis *___________
Respiration *_________
Maintenance respiration *__________________
L.U.E. Model *__________
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Density effect on crop *__________________
-> Biomass
Biomass Pool *__________
Biomass Partitioning *_______________
Crop models *__________
A Crop model example *__________________
Quiz *____
Supplementary resources *___________________

-> Applied Mathematics
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Map *____
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Negative Binomial Law *_________________
-> Dynamic systems
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Negative Exponential *________________
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Parameter Identification *__________________
Parameter estimation *________________
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-> GreenLab courses
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-> Overview
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Plant architecture *_______________
Biomass production *________________
Modelling - FSPM *______________
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-> Principles
Presentation & Objectives *____________________
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-> About modelling
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Inside the growth cycle *___________________
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-> Development
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Map *____
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-> Stochastic modelling
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Branching *________
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-> Organogenesis equations
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-> Structure construction
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Implicit construction *________________
Explicit construction *________________
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-> Production-Expansion
Presentation & Objectives *____________________
Map *____
-> EcoPhysiology reminders
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Temperature *__________
Light interception *______________
Photosynthesis *___________
Biomass common pool *_________________
Density *______
-> Principals
Growth cycle *__________
Refining PbMs *___________
Organ cohorts *___________
GreenLab vs PbM & FSPM *___________________
-> GreenLab's equations
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Plant demand *__________
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Full Model *________
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-> Applications
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Simple development *_______________
Damped growth *____________
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Rhythmic growth samples *___________________
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Branching *________
-> Crown analysis
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-> Case study
Plant Architecture *______________
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-> Tools (software)
Presentation & Objectives *_____________________
Map *____
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Online tools *__________

GreenLab Course

About modelling

Factors affecting plant growth and modelling

Plant growth results from both endogenous processes and environmental factors.

The endogenous process

    The endogenous process drives plant structure establishment
    Plant structure establishment is the final result of endogenous processes.

      Differentiation and production of the various organs can be expressed from rules applied to successive metamers.

      Such rules can be simulated with an automaton.
      Models simulating such organ differentiation are called structural or geometric.
      They aim to generate the plant structure at various ages, up to detailed geometry allowing 3D representations.
      The rules are based on botanical architectural notions. Ideally, for a given species, an efficient model defines rules for each axis typology (each physiological age), suitable for a wide range of plant ages and environmental conditions.

      In the illustrated example the structure is built from five consecutive metamers at the same stage of differentiation.
           The terminal bud reaches then a flowering stage; the growth is thus determinate
            (Drawing and animation P. de Reffye, CIRAD)

       Plant organogenesis raises from an endogeneous process.

Environmental Factors

    Environmental factors also impact on plant growth.

      Resources, and more precisely the supply of water and light, affect organ biomass accumulation and thus organ size.

      Models relative to these aspects are called functional models. Such is the case of process-based models or crop models.

      - Light produces photosynthates via green leaf functioning. Empirically, the effect of incident light is well known. Depending on light intensity, a linear effect can be seen, gradually reaching saturation. Light also has a strong influence on plant plasticity. It can modify plant development by affecting the rules of meristem production. This can be a difficult point for modelling, requiring functional to structural feedback.

      - Water is taken up by roots from the root environment and evaporates by transpiration at leaf level. As both transpiration and photosynthesis are strongly influenced by light intensity, a close relation is often seen between crop transpiration and biomass production. Plant transpiration depends primarily on radiation and leaf area. It can be limited by water shortages in the root environment (stomata will close).
      The cumulated effect of water transpiration over the long term is often linearly related to plant biomass production.

      Modelling biomass production (photosynthesis) is a key point, and mutually benefits from the empirical light effect law and the linear water transpiration / biomass production relation.
      However, biomass attribution to a given organ results from a competition between organs. During growth, available biomass will be alloted to a given organ depending on its sink strength.

      - Temperature also affects growth.
        In most of plants, the structure development steps are governed by the thermal energy received.
        Temperature controls the rate of shoot development and the duration of organ expansion. Within a given temperature range (i.e., when the development rate is linearly related to temperature), there is a linear relationship between the number of phytomers formed on a shoot and the sum of daily effective temperatures received by the plant.

      To sum up, temperature affects the rate of structure development, and light and water affect biomass growth.
      Hence, in advanced models, development cycles are scheduled by thermal time, rather than calendar time.

    Water and light affect organ sizes while temperature affects growth speed.

    Environmental factors illustrating the growth dynamics (Drawing and animation P. de Reffye, CIRAD)
    Left, an endogenous factor. In the illustrated example, the structure is built from five consecutive metamers at the same stage of differentiation. The terminal bud then reaches a flowering stage; growth is thus determinate.
    Middle and right: Environmental factors illustrating growth dynamics. Two levels of resources and three levels of temperature are illustrated.