La transition vers la réduction de l’usage des pesticides au prisme de l’intermédiation

Ce numéro comprend les articles issus du colloque de restitution Ecophyto Recherche « Des outils et des dispositifs pour éclairer les décisions, explorer les possibles et accompagner la transition vers des systèmes économes et multi-performants », qui s’est tenu à Saint-Malo, du 22 au 24 mars 2017National audienceGlobal assessment indicators used to measure the efficiency of the national action plan Ecophyto might hide processes which occur at intermediary level (supply chains, locality, farm). To highlight such processes, we analyse how public policy instruments are used by various AKIS players in relation to the logic supporting their respective collective action. Our results described: (i) the diversity of existing frames related to such logics and their prescriptive dimension regarding intermediary activities; (ii) the way various intermediary players built their relation to technical knowledge and act to legitimise their position and their technical discourse in order to initiate, support and develop the negotiated changes related to less pesticide use; (iii) the objects which are produced and mobilised to support intermediation, their structuring role, and the need to pay attention to the knowledge embedded in these objects as well as to their transformation during the collective action processLes indicateurs globaux d’évaluation pour mesurer l’efficacité du plan Ecophyto peuvent masquer des dynamiques aux niveaux intermédiaires (territoire, filières, exploitation). Pour éclairer celles-ci, nous analysons la façon dont les instruments de politique publique liés au plan sont mobilisés dans des logiques d’action collective portées par divers acteurs au sein du développement agricole. Nos résultats portent sur : (i) la diversité des cadrages liés à ces logiques et la façon dont ils orientent les activités d’intermédiation ; (ii) la façon dont des acteurs intermédiaires construisent un rapport à la technique et une légitimité de leur position et de leur discours sur la technique afin d’initier, accompagner et aider à concrétiser des changements négociés pour réduire l’usage des pesticides ; (iii) les objets produits et mobilisés pour soutenir l’intermédiation, leur rôle structurant, l’attention nécessaire aux connaissances qui les sous-tendent et la façon dont ils se transforment dans l’action collective

Análise de vinte genótipos de sorgo (Sorghum bicolor (L.) Moench), de portes médio e alto, pertencentes ao ensaio nacional Analysis of twenty genotypes of sorghum (Sorghum bicolor (L.) Moench) of medium and high status from the national assay

Os vinte genótipos de sorgo estudados foram cultivados e ensilados aos 104 dias de idade, em estádio de grão pastoso, em silos de laboratório de "PVC", com 10 cm de diâmetro e 40 cm de comprimento. Os silos foram abertos aos 150 dias após a ensilagem. O delineamento adotado foi o inteiramente casualizado. No material estudado (verde e ensilado), foram determinados os valores de fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), hemicelulose, celulose, lignina, cinzas totais, matéria seca (MS), proteína bruta (PB) e carboidratos solúveis em álcool, que apresentaram valores médios de 61,8; 34,2; 27,5; 29,5; 4,6; 3,8; 25,7; 7,7; e 8,5% no material original e de 55,9; 32,6; 23,3; 28,5; 3,9; 4,0; 27,5; 8,6; e 0,8% nas silagens, respectivamente. Os valores de hemicelulose e celulose diminuíram com a ensilagem, indicando que tais frações forneceram carboidratos adicionais para a fermentação. Os teores de carboidratos solúveis do material original foram altos para todos os genótipos, sendo intensamente consumidos no silo, garantindo bom padrão de fermentação. Nas silagens, os valores de pH foram, em média, 3,5 e os teores de nitrogênio amoniacal, inferiores a 8%, em todos os genótipos. As silagens estudadas apresentaram-se iguais para todas as características pesquisadas.<br>The twenty studied genotypes of sorghum were cultivated and ensiled at 104 days of age, at dough grain phase, using "PVC" lab silos, presenting 10 cm diameter and 40 cm length. The silos were opened at 150 days after ensiling. A completely randomized experimental design was used. In the studied material (fresh and ensiled) the values of neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, cellulose, lignin, total ash, dry matter (DM), crude protein (CP) and alcool soluble carbohydrates were determined. The mean values were of 61.8, 34.2, 27.5, 29.5, 4.6, 3.8, 25.7, 7.7 and 8.5% in the fresh matter and of 55.9, 32.6, 23.3, 28.5, 3.9, 4.0, 27.5, 8.6 and 0.8% in the silages, respectively. The hemicellulose and cellulose values decreased with ensiling, indicating that those fractions contributed with additional carbohydrates for the fermentation. The soluble carbohydrates values of the fresh material were higher for all genotypes, being intensively used in the silo, supplying a good fermentation standard. In the silages, the pH values were 3.5 and ammoniacal nitrogen (N-NH3) contents were inferior to 8.0% in all genotypes. The studied silages showed similar for all evaluating characteristics