Plantes, peuplements et paysages : Modèles et méthodes, changements d'échelles

National audienc

Corrigendum to “Comparing an empirical crop model with a functional structural plant model to account for individual variability” [Europ. J. Agronomy 53 (2014) 16–27]

Se réfère à la notice suivante : http://prodinra.inra.fr/record/256421absen

A fast algorithm for calculating stem and branch radial growth in a tree with substructure approach

International audienc

Modelling of branch and flower expansion in GreenLab model to account for the whole crop cycle of Winter Oilseed Rape (Brassica Napus L.)

interesting tools to study interactions between architecture and environmental conditions. In the case of Winter Oilseed Rape (WOSR), we need a plant model that accounts for the role of source:sink relationships in the architectural development. GreenLab model is a good candidate because it was already used to evidence interactions between source:sink relationships and architecture for other species. However, its adaptation to WOSR is a challenge because of the complexity of its developmental scheme especially during reproductive phase. Indeed, we need to take into account the different timings of branch expansion and pod setting. Therefore two equations were added in GreenLab model to compute expansion delays for respectively branching and flowering of each axis.Experimental field data were used to estimate morphological parameters such as phyllochron, podochron,(equivalent to phyllochron but for pods), leaf expansion duration, and leaf life span. These data were also used to calibrate the source:sink module of the model. First results indicated that the model simulates properly the dynamics of plant growth and development during both vegetative and reproductive phases

Stochastic models in floral biology and application to the study of oilseed rape fertility

The number of seeds per pod is an important determinant of yield. New clues of yield and seed quality improvement can be provided by studying the relation between the developmental patterns of floral organs and seed production. In this article, a probabilistic model of plant inflorescence fertility is presented. From a biological point of view, seed development can be viewed as the combination of several physiological processes that can be modeled with stochastic laws. Experiments were made on oilseed rape in Grignon (France) in 2008 to calibrate the model. A generalized least square method is implemented to estimate the model parameters. The variations of parameters are analyzed according to the position of flowers. Furthermore, we discuss the causes that lead to the variation of seed production within the inflorescence and relate them to our model. The model reproduces well the distribution of the number of ovules per flower as well as the number of final seeds per pod. We deduced a law to describe the distribution of pollen grains on the stigma that is quite difficult to be observed experimentally. This model is the first step towards a dynamic model taking into account the complexity of the oilseed rape architecture. Which is aimed to quantify the influence of pollination or trophic competition on seed production

Modelling of branch and flower expansion in GreenLab model to account for the whole crop cycle of Winter Oilseed Rape (Brassica Napus L.)

interesting tools to study interactions between architecture and environmental conditions. In the case of Winter Oilseed Rape (WOSR), we need a plant model that accounts for the role of source:sink relationships in the architectural development. GreenLab model is a good candidate because it was already used to evidence interactions between source:sink relationships and architecture for other species. However, its adaptation to WOSR is a challenge because of the complexity of its developmental scheme especially during reproductive phase. Indeed, we need to take into account the different timings of branch expansion and pod setting. Therefore two equations were added in GreenLab model to compute expansion delays for respectively branching and flowering of each axis.Experimental field data were used to estimate morphological parameters such as phyllochron, podochron,(equivalent to phyllochron but for pods), leaf expansion duration, and leaf life span. These data were also used to calibrate the source:sink module of the model. First results indicated that the model simulates properly the dynamics of plant growth and development during both vegetative and reproductive phases

Calibration of a probabilistic model of oilseed rape fertility to analyze the inter-variety variability in number of seeds

With the objective of using plant models as predictive tools scaling from genotype to phenotype, model parameters should have a strong genetic determinant. For this purpose, the modeling process involves assessing the differences in model parameters between varieties. In this study, a model of flower fertility is used to explain the observed behaviors and to identify the variety related parameters relevant to seed production. The model simulates the steps of seed production: ovule formation, landing of pollen grains on a flower, fertilization of ovule by pollen grains, possible abortion of the fertilized ovules. The aims of this study are to assess the differences of estimated parameters and identify the factors that can explain observed differences among varieties in the number of seeds per pod. Four varieties of oilseed rape (Mendel, Gamin, Exocet and Pollen) were grown at the experimental station of Grignon, France. Ten plants were marked and 15 pods from rank 11 to 40 (to eliminate the effect of position) on the main stem were collected on each plant for each variety. The numbers of seeds and aborted seeds were recorded. The total seed dry weight for each plant was measured. The maximum number of ovules per flower is different among the four varieties with the range of 36-45. The landing of pollen grains on a flower was significantly different among the varieties, although they were grown in the same field. The estimation result of model allows us to conclude that pollination and resource competition have the similar impact on the ovule and seed abortion. However, for the variety Gamin, the probability of fertilized ovules to abort was quite large in agreement with the smaller number of seeds measured but mean seed weight was higher than others (P<0.001, ANOVA). The data analysis indicated that the small number of seeds per pod was compensated by a higher seed weight. The abortion of seeds could result from insufficient pollination and resource competition. Current work aims at quantifying more precisely the roles of these factors and investigating other ones. We intend to use the model to distinguish the effects of different factors on seed production, such as the plant architecture. One way is to compare the behaviors of the main stem, the ramifications and the plants