Services écosystémiques rendus par des mélanges de Brassicacées et de Légumineuses en interculture : gestion de l'azote, du soufre et biocontrôle

National audienc

Services écosystémiques rendus par des mélanges de Brassicacées et de Légumineuses en interculture : gestion de l'azote, du soufre et biocontrôle

National audienc

CRUCIAL -Services écosystémiques produits par les cultures intermédiaires multiservices de légumineuses et de crucifères

Crucifers and legumes multi-services cover crop mixtures are an effective solution to mutualize ecosystemservices related to nitrogen and sulphur cycle while providing a high biocontrol potential on soil-bornpathogens. Mixtures provide the same nitrate and sulfate catch crop services and increase the nitrogenrecycling green manure service compared to crucifers alone. Biocontrol potential of crucifer cover cropswas assessed through their glucosinolate (GSL) production (profile and concentration) which varyaccording to the species but not among cultivars of the same species. In field conditions aliphatic GSLproduced by forage radish seems to reduce incidence and severity of Verticillium dahliae on sunflower.No mortality or flight on wireworm effect from crucifers was highlighted on Agriotes sordidus wireworm ofmaize. Ethiopian mustard seed meal significantly increased wireworm mortality in controlled conditions.Les mélanges de cultures intermédiaires multiservices (CIMS) de crucifères et de légumineusespermettent une mutualisation des services écosystémiques liés aux cycles de l’azote, du soufre, et à leurpotentiel de bio-contrôle sur des bioagresseurs et ravageurs telluriques. Leur association permetd’atteindre un effet piège à nitrate et à sulfate similaire aux CIMS de crucifères pures tout en produisantun meilleur effet engrais vert pour l’azote. Le potentiel de bio-contrôle des CIMS de crucifères a été évaluépar leur production de glucosinolates (GSL) qui varie fortement entre les espèces mais peu entre variétésd’une même espèce. Les GSL de type aliphatique contenus dans le radis fourrager semblent les plus àmême de réduire l’incidence et la sévérité du Verticillium dahliae sur le tournesol au champ. Aucun effetlarvicide ou larvifuge des crucifères n’a pu être mis en évidence sur les larves d’Agriotes sordidus du maïscontrairement au tourteau de moutarde éthiopienne qui augmente significativement la mortalité des larvesen conditions contrôlées

Phoma et dessèchement précoce du tournesol

Cet ouvrage fait le point sur le phoma et le dessèchement précoce du tournesol : connaissances actuelles sur le champignon et la maladie, méthodes de contamination, impact de la conduite de culture, résistance génétique du tournesol au phoma, méthodes de lutte. Il fait suite à de nombreux travaux de recherche, menés principalement en France depuis 5 ans dans le cadre de l’UMT Tournesol à Toulouse par les équipes du CETIOM, de l’EI Purpan, de l’ENSAT et de l’INRA

Control of Verticillium dahliae causing sunflower wilt using Brassica cover crops

Since 2010, sunflower in France has been severely affected by a vascular wilt disease caused by Verticillium dahliae. Disease is widespread and causes significant damage up to 30% yield loss. V. dahliaeis a soil-borne fungus living in roots able to survive in the absence of a host in the form of microsclerotia (MS). Brassica crops used as cover crops can naturally suppress soilborne pathogen viability. This fumigation activity has been linked to volatile isothiocyanates (ITCs) released from glucosinolates (GSLs). In this study, Brassicacover crops of white and brow mustard, radish, rape and rapeseed were evaluated for their ability to reduce the viability and development of V. dahliae. Cultivars were selected by GSL side-chain and concentration, and V. dahliaestrain for its aggressiveness on sunflower. Biofumigation was assessed in a laboratory assay. MS and developed V. dahliaeon growing media were exposed for 20 days to volatile compounds released by fresh or freeze ground plant tissues. The toxicity of ITCs-GSLs on V. dahliaewas assessed by the area under fungus progress curve relating its development on the media. The five Brassicareduced the development and germination of V. dahliaeby 90% (brown-mustard) to 63% (radish), and the development by 90% (rape) to 69% (white-mustard) compared to the control in absence of tissues. Aliphatic GSLs in brown mustard and rape, and indole GSLs in rape and radish may explain the strong reduction of V. dahliaedevelopment and viability respectively. These results indicate that Brassica have potential for use as cover crops for the control of soilborne disease problems and sunflower wilt

Phoma et dessèchement précoce du tournesol

Cet ouvrage fait le point sur le phoma et le dessèchement précoce du tournesol : connaissances actuelles sur le champignon et la maladie, méthodes de contamination, impact de la conduite de culture, résistance génétique du tournesol au phoma, méthodes de lutte. Il fait suite à de nombreux travaux de recherche, menés principalement en France depuis 5 ans dans le cadre de l’UMT Tournesol à Toulouse par les équipes du CETIOM, de l’EI Purpan, de l’ENSAT et de l’INRA

Regulation and recovery of sink strength in rice plants grown under changes in light intensity

International audienceThe aim of this study was to characterise the sequence of traits that influence the response of rice morphogenesis to a shortage in carbohydrate supply and to its recovery. Plants were grown under 70% shading or full-light exposure for distinct periods during the vegetative and early reproductive phases in field and controlled environments. Lower organ vigour (i.e. higher specific leaf area and specific stem length), sugar concentration, tiller emergence and leaf elongation rate; higher leaf blade to sheath length ratio and preferential assimilate allocation to sink (elongating) leaves, were observed soon after the onset of shading. Organ vigour was affected before any appreciable effect on tiller emergence was noted. All the processes resumed after the shading removal, which coincided with a boost in sugar concentration; however, the extent of recovery in organ vigour and tillering depended on the growth stage at which shading was applied. It is concluded that crop response to changes in carbohydrate supply at the early stage favoured leaf area production by adjusting transient reserve levels and biomass allocation. Results of this study provide further insights into the role of soluble carbohydrates in plant and crop phenotypic plasticity and, thus, into the value of such processes in plant growth models