Genetic differences for nitrogen uptake and nitrogen utilisation efficiencies in winter wheat.

Abstract Due to economic and ecological factors, European agricultural practices are likely to go towards extensive systems with lower inputs of nitrogen (N) fertilisers. The objective of this study was to assess varietal differences for N use at two nitrogen levels. A set of 20 winter wheat (Triticum aesti6um L.) genotypes was studied over 2 years in northern France on a deep loam soil without (N0) and with 170 kg ha − 1 N fertiliser (N +) as ammonium nitrate. Results were consistent on both years as the genotype ×year or genotype×year× N level interactions were not significant. The genotype × N level interaction was highly significant except for total N utilisation efficiency (total above-ground dry weight/total above-ground N) and grain N concentration. The genotype ×N level interaction for grain yield was mainly due to three contrasting genotypes: Cappelle, a cultivar from the 1940s, had the same yield at N0 and N + ; Arche had a high yield at both N levels; and Récital had a high yield with added N and a very low one without N. The number of kernels/ear explained most of the variations of grain yield at N0 (48%) and N + (80%), and of the interaction (67%). N uptake efficiency (total above-ground N/soil N supply) accounted for 64% of the variation in N use efficiency (grain yield/soil N supply), while at N0 and at N+ it accounted for only 30%. N utilisation efficiency (grain yield/total above-ground N) was then more important at N + than at N0. Grain N explained most of total plant N variation at both N levels. The interaction for N use efficiency was best explained by the interaction of N uptake (63%). The applications of these results to a breeding programme to create varieties adapted to low-input management systems are discussed

Identification de différences génotypiques dans la réponse aux contraintes environnementales : cas de la concurrence due aux mauvaises herbes dans une culture de blé tendre d'hiver

National audienc

Sélection du blé tendre pour l'agriculture biologique

Face à une demande croissante des consommateurs pour des produits issus de l'agriculture biologique, l'INRA, organisme de recherche publique, contribue par ses travaux au développement de la filière. Cet article relate ce qu'a initié l'Institut en matière de sélection de variétés de blé tendre adaptées aux caractéristiques très particulières de ce mode de culture

Conventional versus organic farming systems: dissecting comparisons to improve cereal organic breeding strategies

“Conventional” and “organic” farming systems have been compared in many studies. However, the lack of concern about the diversity of both conventional and organic farming systems can be imputed to the oft-quoted methodological difficulties of comparing conventional and organic systems. Indeed, the analysis of articles on genotype performance of small-grain cereals under conventional and organic management strategies revealed that there are significant variations in input levels within conventional systems and within organic farming. In addition, this could lead to conflicting results when attempting to identify the best breeding strategies for organic management systems. To boost breeding activities for the organic sector, our proposal is the establishment of an international classification of agroecosystem managements based on recognized agro-climatic and management indicators. Management classifications are proposed for both conventional and organic management strategies. This work would facilitate the sharing of new results among agronomists and breeders for designing adapted and efficient organic breeding strategies

Différences variétales pour le fonctionnement du blé tendre en conditions de nutrition azotée suboptimales

National audienc

Les limites de la comparaison « agriculture conventionnelle » versus « agriculture biologique » dans la définition de stratégies de sélection. Exemple des céréales à paille

National audienc

Conventional versus organic farming systems: dissecting comparisons to improve cereal organic breeding strategies

“Conventional” and “organic” farming systems have been compared in many studies. However, the lack of concern about the diversity of both conventional and organic farming systems can be imputed to the oft-quoted methodological difficulties of comparing conventional and organic systems. Indeed, the analysis of articles on genotype performance of small-grain cereals under conventional and organic management strategies revealed that there are significant variations in input levels within conventional systems and within organic farming. In addition, this could lead to conflicting results when attempting to identify the best breeding strategies for organic management systems. To boost breeding activities for the organic sector, our proposal is the establishment of an international classification of agroecosystem managements based on recognized agro-climatic and management indicators. Management classifications are proposed for both conventional and organic management strategies. This work would facilitate the sharing of new results among agronomists and breeders for designing adapted and efficient organic breeding strategies

Les limites de la comparaison « agriculture conventionnelle » versus « agriculture biologique » dans la définition de stratégies de sélection. Exemple des céréales à paille

National audienc

Nitrogen use efficiency in bread wheat: breeding tools and recent genetic progress

International audienc