66 research outputs found
Using numerical plant models and phenotypic correlation space to design achievable ideotypes
Numerical plant models can predict the outcome of plant traits modifications
resulting from genetic variations, on plant performance, by simulating
physiological processes and their interaction with the environment.
Optimization methods complement those models to design ideotypes, i.e. ideal
values of a set of plant traits resulting in optimal adaptation for given
combinations of environment and management, mainly through the maximization of
a performance criteria (e.g. yield, light interception). As use of simulation
models gains momentum in plant breeding, numerical experiments must be
carefully engineered to provide accurate and attainable results, rooting them
in biological reality. Here, we propose a multi-objective optimization
formulation that includes a metric of performance, returned by the numerical
model, and a metric of feasibility, accounting for correlations between traits
based on field observations. We applied this approach to two contrasting
models: a process-based crop model of sunflower and a functional-structural
plant model of apple trees. In both cases, the method successfully
characterized key plant traits and identified a continuum of optimal solutions,
ranging from the most feasible to the most efficient. The present study thus
provides successful proof of concept for this enhanced modeling approach, which
identified paths for desirable trait modification, including direction and
intensity.Comment: 25 pages, 5 figures, 2017, Plant, Cell and Environmen
A plot drainage network as a conceptual tool for the spatial representation of surface flow pathways in agricultural catchments
International audienceThe drainage network must take the farming systems and the landscape structure into consideration to describe flow pathways in the agricultural catchment. A new approach is proposed to build the drainage network which is based on the identification of the inlets and outlets for surface water flow on each farmers' field (or plot), estimating the relative areas contributing to the surface yield. The delineation of these areas and their links in terms of surface flow pathways provides us with a pattern of relationships between individual plots, i.e. going from each plot to the other plots over the entire catchment. In this approach, flow directions are firstly calculated in the usual way by taking account of slope direction. Plot outlets are defined from the DEM then linked together using a tree structure. If present, linear networks such as hedges modify both the flow directions and the location of plot outlets, hence modify this tree structure. In a final step, the plots are themselves linked together using a graph structure illustrated by an arrow diagram. This drainage network based on plot outlets is applied to a 15-km² catchment area represented by 38,300 pixels and 2,000 plots. This new drainage network takes into consideration 5,300 plot outlets, which greatly reduces the number of objects in comparison with a drainage network made up of pixels or DEM cells. This method leads to a simple and functional representation of surface flow pathways in an agricultural catchment. It allows us to identify the key plots controlling stream water pollution where converging flow pathways are coming from numerous or large-sized plots. Finally it produces a functional representation for decision support
Increased genetic diversity improves crop yield stability under climate variability: a computational study on sunflower
A crop can be represented as a biotechnical system in which components are
either chosen (cultivar, management) or given (soil, climate) and whose
combination generates highly variable stress patterns and yield responses.
Here, we used modeling and simulation to predict the crop phenotypic plasticity
resulting from the interaction of plant traits (G), climatic variability (E)
and management actions (M). We designed two in silico experiments that compared
existing and virtual sunflower cultivars (Helianthus annuus L.) in a target
population of cropping environments by simulating a range of indicators of crop
performance. Optimization methods were then used to search for GEM combinations
that matched desired crop specifications. Computational experiments showed that
the fit of particular cultivars in specific environments is gradually
increasing with the knowledge of pedo-climatic conditions. At the regional
scale, tuning the choice of cultivar impacted crop performance the same
magnitude as the effect of yearly genetic progress made by breeding. When
considering virtual genetic material, designed by recombining plant traits,
cultivar choice had a greater positive impact on crop performance and
stability. Results suggested that breeding for key traits conferring plant
plasticity improved cultivar global adaptation capacity whereas increasing
genetic diversity allowed to choose cultivars with distinctive traits that were
more adapted to specific conditions. Consequently, breeding genetic material
that is both plastic and diverse may improve yield stability of agricultural
systems exposed to climatic variability. We argue that process-based modeling
could help enhancing spatial management of cultivated genetic diversity and
could be integrated in functional breeding approaches
Index
Trépos Pierre. Index. In: Annales de Bretagne. Tome 63, numéro 2, 1956. pp. 291-301
Bibliographie et textes cités
Trépos Pierre. Bibliographie et textes cités. In: Annales de Bretagne. Tome 63, numéro 2, 1956. pp. 285-289
Deuxième partie : assimilation dialectale du froupe singulier + suffixe
Trépos Pierre. Deuxième partie : assimilation dialectale du froupe singulier + suffixe. In: Annales de Bretagne. Tome 63, numéro 2, 1956. pp. 153-216
Les saints bretons dans la toponymie
Trépos Pierre. Les saints bretons dans la toponymie. In: Annales de Bretagne. Tome 61, numéro 2, 1954. pp. 372-406
A propos d'une réédition du "Barzaz Breiz"
Trépos Pierre. A propos d'une réédition du "Barzaz Breiz". In: Annales de Bretagne. Tome 66, numéro 4, 1959. pp. 437-445
Table des matières
Trépos Pierre. Table des matières. In: Annales de Bretagne. Tome 63, numéro 2, 1956. pp. 303-304
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