Une approche génétique pour le contrôle des moisissures nivéales sur les verts de golf

Au Québec, le nouveau Code de gestion des pesticides oblige les propriétaires de terrains de golf à présenter un plan de réduction des pesticides au ministère du Développement durable, de l’Environnement et des Parcs du Québec. La Coalition pour un golf responsable a pour objectif de développer un réseau visant à aider les terrains de golf du Québec à répondre aux exigences gouvernementales et à les supporter devant les problématiques environnementales présentes et futures. Un projet de recherche impliquant des chercheurs d’Agriculture et Agroalimentaire Canada, la Fondation canadienne de recherche en gazon ainsi que la Coalition pour un golf responsable a été initié en 2005 afin d’identifier des génotypes du pâturin annuel, Poa annua, qui combineraient une tolérance supérieure au gel et aux moisissures nivéales

Selection for Improved Saccharification Efficiency in Alfalfa Stems Assessed by Enzyme-Released Glucose

Alfalfa (Medicago sativa L.) has a high potential for sustainable bioethanol production, particularly because of its low reliance on N fertilizer (Samac et al. 2006). Genetic improvement for the accumulation of readily fermentable non-structural carbohydrates (NSC) and the saccharification of structural carbohydrate (SC) could significantly increase ethanol conversion rate. Genetic gains for these traits are tributary to the availability of screening techniques for the precise identification of superior genotypes with increased potential for the production of fermentable carbohydrates. When assessing the genetic variability of parameters linked to cellulosic ethanol production (concentrations of NSC and SC), our results showed a large genetic variability within and among winter hardy- and biomass-type alfalfa cultivars (Duceppe et al. 2012). We also developed an efficient enzymatic assay to measure alfalfa stem degrade-ability, based on the quantity of glucose released by a customized commercially available enzyme cocktail. Despite its robustness, this test is labour intensive, thus limiting analytical capabilities. Near-infrared reflectance spectroscopy (NIRS) was previously shown to successfully predict enzyme released glucose in corn stover (Lewis et al. 2010). This approach allowed us to screen a large number of lignified alfalfa stem samples and to identify superior genotypes. Our objective was to determine if it is possible to develop alfalfa cultivars with superior cell wall (CW) degradability

Carbohydrate to Protein Ratio in Perennial Ryegrass: Effects of Defoliation Stage and Nitrogen Rate

In intensive grass-based systems, perennial ryegrass (Lolium perenne L) grazed at early stages has a high crude protein content (CP) and low water soluble carbohydrate (WSC) relative to animal requirements. This imbalance leads to low nitrogen (N) use efficiency and a large loss of N excreted to the environment (Dijkstra et al. 2011). Previous research has shown the importance of the WSC:PC ratio as a useful factor that determines the improvement of the animal’s performance in terms of nitrogen utilization (Cosgrove et al. 2007). However, little is known about how the management of defoliation at specific growth stages can modify the WSC:CP ratio and other nutritive parameters related to N use efficiency. The objective of this study was to determine the changes of WSC:CP ratio and other nutritive parameters related to N use efficiency in response to nitrogen fertilizer rate and defoliation frequency based on leaf stage

Appariement de contours 2D par analyse multirésolution hiérarchique de la déformation

Cet article présente un algorithme d'appariement de contour basé sur une analyse multirésolution de la courbure. L'appariement point à point est particulièrement intéressant pour l'analyse de la déformation puisqu'il fournit un champ de déformation complet entre deux contours. Le critère de courbure permet d'étudier des déformations importantes mais il est extrêmement sensible au choix de l'échelle de mesure. Nous résolvons ce problème par une approche hiérarchique multirésolution qui nous permet de tenir compte de tous les niveaux de résolution des contours avec le seul critère de courbure. Notre algorithme est basé sur une décomposition des contours dans la base de Fourier et un appariement par programmation dynamique

Increased Sugar Concentration with PM-Cutting and Wide Swathing Improves Alfalfa Silage Fermentation

Extensive protein degradation during silage fermentation reduces the efficiency of N utilization by ruminants and excess N is excreted in the environment. Forage nonstructural carbohydrates (NSC) represent the main source of readily fermentable energy for lactic bacteria during silage fermentation. Increasing forage NSC concentration can enhance silage fermentation, lactic acid production, and the decline in pH with an overall reduction in the extent of protein degradation. The NSC concentration increases during the day in alfalfa (Medicago sativa L.) to reach a maximum by the end of the afternoon. Under good wilting conditions, PM-cut alfalfa wilted in wide swaths had a greater NSC concentration than AM-cut alfalfa (Morin et al. 2012). Our objective was to study the effect of PM cutting and wide swathing on alfalfa silage quality attributes

High-Sugar Alfalfa for Dairy Cows

Alfalfa proteins are extensively degraded during wilting, silage fermentation, and in the rumen. To efficiently use alfalfa non protein N, rumen microbes need a readily available energy source such as nonstructural carbohydrates (NSC); otherwise, surplus N in the form of rumen ammonia is converted into urea and excreted in the environment. Increasing the NSC concentration of alfalfa was thus the focus of our research program. Our objectives were to assess the impact of high NSC alfalfa on digestibility and microbial protein synthesis measured in vitro, and on ingestion, rumen metabolism, N use efficiency, and dairy cow performance. Increasing NSC concentration of alfalfa significantly enhanced in vitro dry matter (DM) digestibility and decreased NH3-N concentration in rumen fluid. An increase of 23 g/kg in alfalfa NSC concentration can improve forage DM intake (+5 %) and energy corrected milk production (+8 %). Feeding high-NSC alfalfa led to a higher rumen pH, suggesting that sugars do not cause rumen acidosis, and to a lower milk urea N (MUN) indicating an improvement in N utilization. Increasing NSC concentration of alfalfa is a low-cost tool to improve its utilisation in dairy rations and potentially mitigate the environmental footprint of milk production