Modélisation des effets des systèmes de culture sur la levée des adventices à partir de relations fonctionnelles utilisant les traits des espèces

The aim of the Ph. D. Was to adapt the monospecific model ALOMYSYS to a multi-specific flora, in order to predict the effects of cropping systems on the timing and quantities of emerging weed seedlings. Determining the parameters for each additional species is unfeasible. A second objective was thus to estimate the parameters from easily measurable species traits. After having performed a large literature analysis, 18 weeds were studied for the processes involved into the seedbank dynamics and emergence. The seed mortality in the soil could not be related with species traits and can be parameterised with literature data. A generic and simplified formalism represens the seasonal variations o…

Dormancy and longevity of soil-buried weed seeds : from examples to generalization

EA SPE EcolDur GEAPSI CT3 CT1EA SPE EcolDur GEAPSI CT3 CT1; The main part of the life-cycle of weeds, especially in cultivated fields, is spent as seeds buried in the soil. Longevity and dormancy are two major traits driving weed survival and infestation in the framework of crop rotation and management. Modelling allows inference of these key processes from morpho-anatomical description of the seeds, thus avoiding long-term germination studies of buried seeds over the years. Two new sets of experimental data on two different weeds offer the opportunity to compare actual results to predicted values. This study deals with cornflower (Centaurea cyanus), a winter weed of cereals and oilseed rap…

Biodiversity-based agroecological system experiment: what, why, how?

Weed-DATA Base de données ‘Traits’ des plantes adventices des agroécosystèmes

SPEEAECOLDURGEAPSIéquipe CAPA; absent

Prediction of germination rates of weed species: Relationships between germination speed parameters and species traits

International audience; In fields, the timing of weed emergence flushes is mostly related to the timing and rate of seed germination, which depend on seed dormancy level, soil temperature and water potential conditions as well as soil tillage and crop sowing date. Seed germination parameters are essential in weed dynamics models to account for the effects of soil conditions on weed demography. Since these parameters are difficult to measure, our objective was to test the possibility of estimating them from easily accessible information. Seed germination parameters (germination lag-time, time to mid-germination and mid-germination rate) were measured or collected from the literature for 25 w…

Effects of the spatio-temporal arrangement of agroecological cropping systems on generalist predators and biological regulation

Facing the current agricultural challenges, agroecological systems place ecosystem services at the core of their production processes. Among these services is induced biological regulation, which keeps pest populations below an acceptable level in order to meet agronomic objectives. Despite the fact that this service is the result of an active scientific field, the effects of cropping systems that enhance regulation at supra-parcel scales are poorly understood. It is therefore essential to assess the effect of various cropping systems and agro-ecological infrastructures on natural enemy communities, as well as their resulting biological regulation potential, at broad spatio-temporal scales.…

Le rôle des modèles pour l'évaluation multicritère et la conception multi-objectif de systèmes de culture pour la gestion des adventices

Weeds are both harmful for crop production and important for biodiversity in agricultural landscapes. Moreover, we need to reduce herbicide use to limit environmental impacts. We therefore must design new cropping systems optimising all cultural techniques and reconciling agricultural production on one hand, herbicide reduction and biodiversity on the other hand. The objective of our study was to illustrate how to (1) develop models quantifying the effects of cropping systems on weed dynamics, (2) integrate interactions between weeds and other biotic components, (3) translate weed flora into a series of indicators of the impact on production and biodiversity, (4) use the model for multicrit…

Evaluation and comparison of pollination service indicators at agricultural landscape level

The current pollinator decline is a major issue, notably because one-third of the world agricultural production depends on pollination. However, quantifying whether the loss of some pollinators translates into less efficient pollination remains challenging, particularly at the scale of farmland territories, which is a relevant scale for action. On the one hand, clear links have been established between the abundance and diversity of pollinators and pollination efficiency only over relatively small areas, because time-consuming experimental methods prohibit studies over broader areas. On the other hand, nationwide or continentwide indices exist but they either measure potential pollination o…

Effects of seed traits on weed seedbank dynamics in response to seed depth and soil structure

International audience; Weed seedling establishment in fields strongly depends of soil tillage because it determines both seed depth and soil structure. Species can differ in their ability to develop after germination a shoot able to grow towards the soil surface. The length of the pre-emergent shoot growth is limited and seed size could be a key functional trait related to the maximum shoot growth. Besides, during pre-emergent growth, a proportion of seedlings can remain blocked under obstacles into the soil. This mortality could be linked to the hypo- or epicotyl morphology. This trait could be correlated to the emergence force exerted at the extremity of the shoot in the soil. The maxima…

Assessing of base temperatures and base water potentials for germination of weeds

International audience

Effets des modalités de préparation des sols et de semis sur la flore adventice

Prod 2020-1 EA GESTAD INRA; National audience; résumé du livre : Pour les cultures semées, l’implantation est une phase critique du cycle, à fortsimpacts agronomiques et environnementaux. Elle est au coeur de la transitionagroécologique des systèmes de culture, avec des options de plus en plusdiversifiées.Aujourd’hui, l’implantation des cultures est affectée par de multiples évolutions :simplification du travail du sol, complexification des couverts végétaux etsuccessions culturales, restriction des traitements phytosanitaires, déplacementdes périodes de semis, agrandissement des exploitations, innovation dans lesagroéquipements… Avec la protection intégrée, c’est le domaine sur lequel lade…

How to choose model weed species for analysing the emergence processes in cropping systems? A review

International audience

The response of weed and crop species to shading: measurement and prediction from traits

International audience; Crops compete with weeds for light, and choosing competitive crop species is a major lever for managing weeds. The present study aimed to (1) measure the range of species parameters that drive light competition in contrasting crop and weed species of temperate European arable crops, (2) relate the parameter values which are difficult to measure to species traits that are easier to access, by establishing trait-parameter relationships, (3) integrate the measured parameter values into the FlorSys model which simulates weed dynamics and crop canopy growth in virtual fields over the years with a daily time step, and (4) run simulations to investigate which crop and weed …

Field boundary: an atypic area and flora

International audience

Quels traits des cultures et des adventices expliquent la perte de rendement due à la compétition pour la lumière ?

National audience; Cultures et adventices sont en compétition pour la lumière, et choisir des cultures compétitives est un levier majeur de gestion intégrée des adventices. L'objectif de cette étude était de : (1) mesurer les paramètres qui déterminent la compétition pour la lumière de 25 espèces adventices et 30 cultures ; (2) établir des relations fonctionnelles pour estimer ces paramètres difficiles à mesurer à partir de traits d'espèces faciles à mesurer ou accessibles dans des bases de données ; (3) intégrer les paramètres dans le modèle FLORSYS qui simule la dynamique de levée des adventices et la croissance des adventices et cultures dans un champ virtuel au fil des années; (4) ident…

Response and effect traits of arable weeds in agro-ecosystems: a review of current knowledge.

25 pages; International audience; Integrating principles of ecological intensification into weed management strategies requires an understanding of the many relationships among weeds, crops and other organisms of agro-ecosystems in a changing context. Extensively used during the last two decades in weed science, trait-based approaches have provided general insights into weed community response to agricultural practices, and recently to understanding the effect of weeds on agro-ecosystem functioning. In this review, we provide a holistic synthesis of the current knowledge on weed response and effect functional traits. Based on the literature and recent advances in weed science, we review cur…