Team Virtual Plants

Overall Objectives
Scientific Foundations
New Results
Other Grants and Activities

Section: New Results

Analysis of structures resulting from meristem activity

Acquisition and design of plant geometry

Participants : Chakkrit Preuksakarn, Frédéric Boudon, Christophe Pradal, Christophe Godin.

This research theme is supported by RTRA project PlantScan3D.

Virtual 3D model of plants are required in many areas of plant modelling. They can be used for instance to simulate physical interaction of real plant structures with their environment (ligth, rain, wind, pests, ...), to set up initial conditions of growth models or to assess their output against real data. In the past decade, methods have been developed to digitize plant architecture in 3D [40] , [28] . These methods are based on direct measurements of position and shape of every plant organ in space. Although they provide accurate results, they are particularly time consuming. More rapid and automated methods are now required in order to collect plant architecture data of various types and sizes in a systematic way. In this topic, we explore the use of laser scanner and direct sketching. Resulting models should be parsimonious. We also consider the definition of methods to post-process these complex representations into compact ones and apply them on streaming.

Modeling the plant ontogenic programme

Participants : Christophe Godin, Yann Guédon, Evelyne Costes, Jean-Baptiste Durand, Pascal Ferraro, Yassin Refahi, Etienne Farcot.

This research theme is supported by a PhD programme.

The remarkable organization of plants at macroscopic scales may be used to infer particular aspects of meristem functioning. The fact that plants are made up of the repetition of many similar components at different scales, and the presence of morphological gradients, e.g. [22] , [30] , [31] , [6] , provides macroscopic evidence for the existence of regularities and identities in processes that drive meristem activity at microscopic scales. Different concepts have been proposed to explain these specific organisations such as "morphogenetic programme" [36] , "age state" [27] or "physiological age" [23] . All these concepts state that meristem fate changes according to position within the plant structure and during its development. Even though these changes in meristem fate are specific to each species and lead to the differentiation of axes, general rules can be highlighted [27] , [23] . Here we develop computational methods to decipher these rules.

Analyzing the influence of the environment on the plant ontogenic programme

Participants : Florence Chaubert-Pereira, David Da Silva, Damien Fumey, Frédéric Boudon, Christophe Godin, Yann Guédon, Christian Cilas, Evelyne Costes, Pascal Ferraro, Christian Lavergne, Hervé Sinoquet, Catherine Trottier.

This research theme is supported by a CIFRE contract and two PhD programmes.

The ontogenetic programme of a plant is actually sensitive to environmental changes. If, in particular cases, we can make the assumption that the environment is a fixed control variable (see section 6.1.2 ), in general the structure produced by meristem results from a tight interaction between the plant and its environment, throughout its lifetime. Based on observations, we thus aim to trace back to the different components of the growth (ontogenetic development and its control by the environment). This is made using two types of approaches. On the one hand, we develop a statistical approach in which stochastic models are augmented with additional time-varying explanatory variates that represent the environment variations. The design of estimation procedures for these models make it possible to separate the plant ontogenetic programme from its modulation by the environment. On the other hand, we build reactive models that make it possible to simulate in a mechanistic way the interaction between the plant development and its environment.


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