Search results for "azot"
showing 10 items of 137 documents
Analysing and modelling the effect of nitrogen competition in weed regulation.
2020
Reducing the use of herbicide and mineral fertilizers is crucial to develop sustainable cropping systems. Such changes might result in an increased weed flora as well as intensify competition for resources, particularly nitrogen, between crops and weeds. The aim of this thesis was to analyze and model (via the mechanistic crop model FLORSYS) the key processes underlying nitrogen competition, in order to determine if changes in nitrogen fertilization techniques and cultivar choice could promote biological weed regulation.At the beginning of the thesis, the FLORSYS model (which simulates the effects of cropping systems in interaction with pedoclimate on weed dynamics) only included light comp…
Cyclodextrines confinantes : synthèse, propriétés complexantes et utilisation en catalyse asymétrique
2014
This manuscript is concerned with the design of novel catalytic systems derived from metallocyclodextrins. The first part describes new ways of functionalising the cyclodextrin primary face regioselectively for accessing inherently chiral P,P’ chelators. These heterodentate ligands gavequantitatively cis-chelate complexes with various d8 cations. Their rhodium(I) complexes were assessed in the asymmetric hydrogenation and hydroformylation of prochiral olefins. Thecoordination and catalytic properties of two phosphines derived from a- and b-cyclodextrin are also reported. With their phosphorus lone pair pointing toward the CD core, these confining ligands force the coordinated metal centre t…
Nitrogen fixation and methanotrophy in forest mosses along a N deposition gradient
2013
Abstract Nitrogen deposition has decreased the plant-associated nitrogen (N 2 ) fixation when measured using the indirect acetylene reduction assay (ARA). However, nitrogen deposition can also lead to changes in the diversity of moss symbionts, e.g. affect methanotrophic N 2 fixation, which is not measured by ARA. To test this hypothesis we compared ARA with the direct stable isotope method ( 15 N 2 incorporation) and studied methanotrophy in two mosses, Hylocomium splendens and Pleurozium schreberi , collected from seven forest sites along a boreal latitudinal N deposition transect. We recognized that the two independent N 2 fixation measures gave corresponding results with the conversion …
Research of genetic and molecular determinants involved in the nodulated root system architecture of legumes and contributing to improved nitrogen nu…
2016
Grain legume pulse crops are of great interest to allow a production of seeds high nutritional value without any contribution of nitrate fertilizer. The nitrogen nutrition of legumes depends indeed mainly on the fixation in nodules of atmospheric dinitrogen through the plant-rhizobium symbiosis, and to a lesser extent, absorption by roots of soil mineral nitrogen.A better understanding has been obtained on the genetic control of the development of roots and nodules and on their impact on nitrogen nutrition. High genetic variability of these characters has been detected, and the existence of genetic correlations between them demonstrated. A quantitative genetic approach has identified severa…
Effect of nitrogen nutrition on Medicago truncatula resistance against Aphanomyces euteiches
2016
Nitrogen (N) is a major limiting factor for plant growth. N availability can also impact plant resistance to pathogens by regulating plant immunity. To better understand the links between N nutrition and plant defense, we analyzed the impact of N availability of plant on Medicago truncatula resistance to the root pathogen, Aphanomyces euteiches, taking into account plant genetic variability. This oomycete is considered as the most limiting factor for legume production. Two conditions of N nutrition, non-limiting or deprived in N, and ten plant genotypes were tested in vitro. The results showed that the resistance is modulated by nutritional conditions, depending on plant genotype. Analysis …
Finocchio in Sicilia
2013
Apport de matières organiques exogènes en agriculture: indicateur de potentialité de stockage de carbone dans les sols et définition de classes de di…
2007
CT3; absent
Importance de la variabilité génétique bactérienne sur le fonctionnement de la symbiose Rhizobium leguminosarum biovar viciae avec le pois (Pisum sat…
2008
Les irrégularités de rendement et de teneur en protéine des graines que présente la culture du pois sont, en partie, liées à des problèmes de nutrition azotée. En tant que légumineuse, la nutrition azotée du pois repose à la fois sur la fixation symbiotique de l’azote atmosphérique et sur l’absorption racinaire des nitrates du sol. Notre principal objectif a été de déterminer si le partenaire bactérien, Rhizobium leguminosarum biovar viciae (Rlv), peut être un facteur limitant de la nutrition azotée et du rendement du pois. La variabilité génétique des Rlv et les facteurs influençant la structure des populations de Rlv à l'état libre et symbiotiques ont été étudiés. La signification de la d…
Effetti della concimazione fogliare con urea e con estratti proteici sui descrittori fisici, chimicie biochimici della qualità di un suolo vulcanico …
2005
La produttività di una coltura e la qualità delle produzioni sono strettamente correlate alla disponibilità dei nutrienti nel suolo. In passato, la concimazione era vista quasi esclusivamente come mezzo per massimizzare le produzioni unitarie delle colture mentre venivano trascurati alcuni aspetti, oggi divenuti fondamentali come, per esempio, il mantenimento di ottimi livelli di fertilità del terreno in assenza di rischi di inquinamento ambientale. La valutazione della fertilità complessiva di un suolo e della relativa qualità è, pertanto divenuto, uno dei principali fattori ai fini dello sviluppo di modelli colturali a basso impatto ambientale. Nella presente nota si riferisce dei primi r…