AlomySys: Modelling black-grass (Alopecurus myosuroides Huds.) germination and emergence, in interaction with seed characteristics, tillage and soil climate. II. Evaluation

International audience; Weed emergence models are increasingly necessary to evaluate and design cropping systems. The model AlomySys was developed for a frequent and harmful weed, i.e. Alopecurus myosuroides Huds. [Colbach, N., Dürr, C., Roger-Estrade, J., Caneill, J., 2005a. How to model the effects of farming practices on weed emergence. Weed Res. 45, 2–17; Colbach, N., Dürr, C., Roger-Estrade, J., Chauvel, B., Caneill, J., 2005b. AlomySys: modelling blackgrass (Alopecurus myosuroides Huds.) germination and emergence, in interaction with seed characteristics, tillage and soil climate. I. Construction. Eur. J. Agronomy] and is based on sub-models predicting (a) soil environment (climate, s…

Response of weed species to water stress: quantification and formalisation in a model of crop-weed interactions

International audience; Reducing herbicide use requires alternative strategies to regulate weeds. In the context of climate change, these alternative strategies must tolerate climatic hazards, among which is water deficit. Simulations models that predict the effects of cropping systems, in interaction with pedoclimate, on crop-weed demography are powerful tools to identify weed management strategies that tolerate climatic hazards. However, due to knowledge gaps, competition for water is rarely included in models of crop-weed demography, which can thus not be used to identify weed management strategies that tolerate water deficit. The present study aimed to quantify the response of weed spec…

Carry over effects of cover crop mixtures and management practices on subsequent crops and weeds in no-till systems

Cover crop (CC) mixtures appear as a promising agroecological tool to suppress weeds andmaintain crop productivity while reducing chemical inputs such as herbicides and nitrogenfertilizers. The weed suppressive effect of CC and CC nitrogen release have been related to CCcomposition, soil resource availability and CC termination methods but the relative effect ofthese factors and their interactions remain poorly documented, especially in the case of CCmixtures. Most studies have focused on the subsequent spring crop, and hence, lacked toinvestigate long-term carry over effects of CC. A two field: year experiment was conducted toinvestigate the effect of CC mixture (2 or 8 species including o…

Gestion des adventices en semis-direct : l’effet du couvert varie selon les ressources du sol et le mode de destruction du couvert

National audience; Un essai pluriannuel en semi-direct a testé l’effet des couverts sur la flore adventice et sur les cultures suivantes conduites sans fertilisation et sans désherbage. Une augmentation du nombre d’espèces cultivées dans un mélange ne permet pas de mieux concurrencer les adventices. Un apport d’azote au semis permet au couvert de produire plus de biomasse de couvert mais ne réduit pas le salissement dans le couvert. Comparé à l’action du gel ou au roulage des couverts sur le gel, la destruction chimique du couvert (glyphosate) a réduit l’infestation des adventices dans la culture suivante. Les couverts ne peuvent pas à eux seul assurer une régulation complète des adventices…

Effects of species and soil-nitrogen availability on root system architecture traits - study on a set of weed and crop species

Better managing crop : weed competition in cropping systems while reducing both nitrogen and herbicide inputs is a real challenge that requires a better understanding of crop and weed root architecture in relation to soil-nitrogen availability. An original approach was used which considered the parameters of a simulation model of root architecture as traits to analyse (a) the interspecific diversity of root system architecture, and (b) its response to soil-nitrogen availability. Two greenhouse experiments were conducted using three crop and nine weed species grown at two contrasted concentrations of soil-nitrogen availability. Plant traits were measured to characterise both overall plant gr…

What are the biological determinants of regeneration of perennial weeds? Effect of fragment weight and bud number on the regrowth of five perennial weed species

Perennial weeds have become an increasing problem with the reduction of herbicide use andtillage. Because of their capacity to regenerate from vegetative organs, such as roots andrhizomes, they must be controlled with different management techniques than annuals. Todate, few studies exist on this topic and farmers often lack solutions to control perennials intheir cropping systems. Management strategies must focus on the depletion of theregenerative organ reserves to hamper the production of new shoots. However, there is aneed for a better understanding of below-ground organs physiology and the determiningfactors of their regrowth capacities.Our aim was to assess the number of shoots and th…

Effect of tillage on weed seed dispersal in fields, in interaction with soil structure and tillage depth

International audience

Weed suppression in cover crop mixtures under contrasted levels of resource availability

Cover crop (CC) mixtures appear as a promising agroecological tool for weed management.Although CC supress weed growth by competing for resources, their suppressive effect undercontrasting levels of soil resource availability remains poorly documented. A two field: yearexperiment was conducted to investigate the weed suppressive effect of four CC mixtures.They were composed of 2 or 8 species including or not legume species and compared to abare soil control. The experiment included two levels of irrigation and nitrogen fertilisation atCC sowing. The objectives were to assess (i) weed and CC aboveground biomass response toCC mixtures and resource availability, (ii) the weed suppressive effec…

Coupler l’utilisation d’un modèle de simulation et d’une plateforme de phénotypage à haut débit pour caractériser la réponse des adventices à une limitation en eau

National audience; Mieux comprendre les interactions entre compétition pour la lumière et pour l’eau est nécessaire pour concevoir des stratégies durables de gestion des adventices, dans un contexte de changement global. L’objectif de cette étude était de quantifier la réponse de trois espèces adventices à une limitation en eau et, pour cela, de tester une approche méthodologique innovante couplant l’utilisation d’une plateforme de phénotypage à haut débit et d’un modèle de simulation (FLORSYS). Cette étude a permis d’analyser la diversité des réponses des espèces adventices au stress hydrique et de hiérarchiser les processus en fonction de l’intensité de leur réponse à une limitation en ea…

What are the biological determinants of regeneration of perennial weeds ? Effect of fragment weight and bud number on the regrowth of Elymus repens

Perennial weeds have become an increasing problem with the reduction of herbicide use and tillage. Because of their capacity to regenerate from vegetative organs, such as roots and rhizomes, they must be controlled with different management techniques than annuals. To date, few studies exist on this topic and farmers often lack solutions to control perennials in their cropping systems. Management strategies must focus on the depletion of the regenerative organ reserves to hamper the production of new shoots. However, there is a need for a better understanding of below-ground organs physiology and the determining factors of their regrowth capacities. Our aim was to assess the number of shoot…

L’architecture racinaire des adventices en relation avec la disponibilité en azote du sol

EASPEGESTAD INRA; Mieux gérer la compétition culture : adventice dans des systèmes de culture moins dépendants de l’azote minéral et des herbicides nécessite de mieux connaître l’architecture racinaire des cultures et des adventices en lien avec la disponibilité en azote du sol. Pour cela, nous avons mené deux essais en serre sur douze espèces cultivées et adventices, cultivées à deux concentrations contrastées en azote du sol. Nous avons utilisé les paramètres d’un modèle d’architecture racinaire comme traits pour comparer les espèces et analyser la réponse de l’architecture racinaire à la disponibilité en azote. Les traits racinaires étudiés sont variables entre les espèces mais peu affec…

Mise au point d’un dispositif experimental pour caractériser le tropisme racinaire

EASPEGESTAD INRA; Le tropisme racinaire correspond à l’orientation des racines au sein d’un système racinaire. On parle de gravitropisme positif lorsque le système racinaire s’étend principalement dans une direction verticale, et de plagiotropisme lorsque la direction est principalement horizontale, toutes les situations existant entre ces deux extrêmes. Notre objectif a été de mettre au point un dispositif permettant l’étude du tropisme racinaire adapté à une majorité d’espèces herbacées annuelles (adventices et cultivées, monocotylédones et dicotylédones), et permettant une croissance en 3-D du système racinaire. Le dispositif est constitué d’un bac contenant du sol, ainsi que des cadres …

Legacy Effects of Contrasting Long-Term Integrated Weed Management Systems

To reduce reliance on herbicides and maintain crop productivity, integrated weed management (IWM) seeks to optimize synergies between diverse sets of weed management practices combined at the cropping system scale. Nevertheless, data on weed community response to the long-term implementation of IWM practices remain scare. Here, we assessed the effects of four IWM systems with contrasting objectives and practices (S2: transition from superficial tillage to conservation agriculture; S3: no-mechanical weeding; S4: mixed mechanical and chemical weeding; S5: herbicide-free; all with 6 year rotations) compared to a conventional reference (S1: herbicide-based with systematic plowing and a 3 year r…

Carry over effects of cover crop mixtures and management practices on subsequent crops and weeds in no-till

The response of weed species to water stress

International audience; Reducing herbicide use requires identifying alternative strategies to regulate weeds. Using crop species that are more competitive for resources than problematic weed species is one lever, but requires a better understanding of weed response to water stress. The present study aimed to quantify the response of three weed species to water stress. In a greenhouse experiment, Alopecurus myosuroides, Amaranthus hybridus and Abutilon theophrasti were grown at 4-5 water regimes, ranging from 75 to 20% of the water holding capacity. Plants were grown individually in pots. Each pot was automatically weighted three times per day, and watered whenever necessary to reach the tar…

Gestion des adventices en semis direct : effet des couverts et de leur conduite

National audience; Un essai pluriannuel en semis-direct a testé l’effet de couverts (quatre mélanges comparés à du sol nu) sous divers niveaux de ressources (en azote et en eau) sur la flore adventice et sur les cultures suivantes de la succession (orge de printemps puis lin d'hiver) conduites sans fertilisation et sans désherbage. Une augmentation du nombre d’espèces cultivées dans un mélange ne permet pas de mieux concurrencer les adventices. Un apport d’azote au semis permet au couvert de produire plus de biomasse de couvert mais ne réduit pas le salissement dans le couvert. Comparé à l’action du gel ou au roulage des couverts sur le gel, la destruction chimique du couvert (glyphosate) a…