Azote, rendement et qualité des graines : mise au point et utilisation du modèle Azodyn-colza pour améliorer les performances du colza vis-à-vis de l’azote

Nitrogen management is complex in oilseed-rape for several reasons: the crop can uptake high amounts of nitrogen during autumn, but a part of this nitrogen is lost through leaves fall during winter and spring, event if these fallen leaves are mineralized and contribute partly to the crop nitrogen nutrition. Moreover, recent results have shown that some periods of N deficiency during the crop cycle are not detrimental for yield. Finally, higher seed oil content are obtained with lower nitrogen fertilisation. All these results suggest that a sub-optimal nitrogen nutrition of the crop could lead to high yields and high seed quality, with low losses through environment. In order to design such fertilisation strategies, the use of a crop model, simulating the variables determinant in the yield and grain quality formation and their interaction with environment, can help advisors. As numerous results on the yield and quality determinants of a rape crop have been obtained in the recent years, the available Azodyn-wheat model has been adapted to the specificities of this crop, based on this knowledge. This paper aims at describing the main results on yield and quality elaboration of a rape crop, and then the designing of the Azodyn-rape model. Then, some results of the model evaluation are given and uses of the model for nitrogen fertilisation management are proposed.