Search results for "Semence"
showing 10 items of 11 documents
Modélisation des effets des systèmes de culture sur la levée des adventices à partir de relations fonctionnelles utilisant les traits des espèces
2008
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…
Les semences de la plante parasite orobanche rameuse ont une dormance saisonnière qui varie au niveau intraspécifique et une faible mortalité au champ
2019
L’orobanche rameuse (Phelipanche ramosa) est une plante parasite bioagresseur majeur du colza en France. Les connaissances sur la viabilité et la dormance de ses semences dans le sol sont cruciales pour contrôler l’orobanche mais restent à acquérir. La présente étude vise à quantifier ces processus grâce à une expérience d’enfouissement de semences au champ de deux ans. Deux populations génétiquement distinctes ont été étudiées, collectées sur colza d’hiver et chanvre respectivement. La mortalité des semences est très faible pour les deux populations (4-7% par an). Les semences montrent une dormance saisonnière dont le timing et l’amplitude varient en fonction de la population, avec une dor…
Semences agricoles : la tragédie d'un « bien commun »
2017
L'histoire du statut juridique des semences agricoles est celle d'une tragédie. La multiplication des droits de propriété sur le végétal, facilitée par un système de libre accès à la ressource génétique, a dépossédé les agriculteurs d'une part de leur identité et de leur patrimoine. Et si la réappropriation des semences par les producteurs passait par de nouvelles formes de gestion collective et locale, inspirées des réflexions sur les « communs » ?
Étude de la biologie d'une messicole en régression: le bleuet (Centaurea cyanus L.)
2011
Agroecosystems are currently experiencing high biodiversity loss, in particular among the plant species specifically adapted to this habitat. This decline results from cropping systems that have been intensified in Western Europe since the 1950s. The cornflower (Centaurea cyanus L.), considered as emblem of the flora associated with traditional cereals, appears as a species that may be at risk and should be monitored. Indeed, cornflower can serve as a host to predators of crop pests and is strongly attractive for the pollinators. This study examines the biological factors that could potentially cause the decline of this species: spatial distribution, potential for growth, population's genet…
Effect of inoculation with selected Bradyrhizobium spp. on the survival and growth of Acacia mangium saplings after 20 months in the field
1999
This work was designed to test the long-term effect of the inoculation of #Acacia mangium# seedlings with 10 selected strains of #Bradyrhizobium spp.#. The percentage of survival of seedlings inoculated with any of the #Bradyrhizobium# strains was increased by 10% as compared to the control plants. However, out of the 10 #Bradyrhizobium# strains tested, only 3 strains, Aust l3c, Lu 4 and Tel 8, belonging to the phylogenelic group 1, significandy enhanced the growth of #A. mangium# after 20 months in the field. For the first time, inoculation with indigenous Malaysian strains #Bradyrhizobium# such as Tel 8 and Lu 4 at the seedling stage is reported to produce enhanced and sustained growth an…
Modelling crop rotation including temporary grasslands for weed management
2014
Session 3 - Crop modellingEAEcolDur; absent
Cropping system dynamics, climate variability, and seed losses among East African smallholder farmers: a retrospective survey.
2014
Abstract Climate variability directly affects traditional low input and rain-fed farming systems, but few studies have paid attention retrospectively to the cropping system’s ability to mitigate climate risk. This study analyzes the impacts of rainfall variability on farmers’ seed variety losses over time, considering changes in smallholder farming systems. The cropping system dynamics, in favoring maize at the expense of sorghum and pearl millet, have induced an increasing risk of seed loss during drought. Combining ecological anthropology and climatology, a retrospective survey asking farmers about the period 1961–2006 was carried out at three altitudinal levels (750, 950, and 1100 m) on …
Un état des connaissances sur la prédation des graines adventices par les invertébrés
2013
Adopting agro-ecological management in farming systems requires a good knowledge of the different organisms that interact within the agorecosystem. Research on weed seed predation by invertebrates (Coleoptera, Adephaga, Carabidae) is booming. Here, we present an overview of current available knowledge on this ecosystem service and factors that may be important to enhance it.
Fortes températures : conséquences sur le rendement, la composition et la germination des graines
2012
BAPGEAPSICT ?; absent
Modeling and energy optimization of the operative parts of an air assisted drill
2016
In the context of sustainable farming, the optimization of the energy costs of agricultural operations allows shorter working times and high quality of the agricultural operations. This question relates particularly to the seeding. This operation one is decisive for the quality of the future harvest. The modern high capacity seed drills must be compatible with all the constraints. The main goal of this PhD thesis is thus to develop an innovative methodology, integrating the modeling tools, in order to reduce the energy consumption of the heavy seeding equipment. Thus, we explored four key aspects concerning air seed drill design: maneuverability of poly-articulated seed drills; establishmen…