Nitrogen (N) plays a critical role in crop production. Nowadays, it is possible to detect quantitative trait loci (QTL), as well as their effects and positions on chromosomes, by new molecular and biometrical methods. A doubled haploid rapeseed population of 142 lines from the doubled winter rapeseed cultivars Mansholt's and Samourai, and a framework map derived from an RFLP map were used for the analysis of QTL and their interactions with N in terms of some yield components obtained from field trials in Brassica napus L. The interactions between traits and N were determined by variance analysis. Two QTL for number of seeds per pod, and four QTL for thousand seed weight were mapped at N0 (0 kg/ha N). Three QTL for pod length, two QTL for number of seeds per pod and three QTL for thousand seed weight were mapped at N1 (240 kg/ha N). All the QTL of N0 and N1 were mapped by analysing QTL x N interactions for all traits. Although it was found that there was no interaction between the mapped QTL and N, the results here can be used to improve the N-use efficiency and seed yield of Brassica napus.

Nitrogen (N) plays a critical role in crop production. Nowadays, it is possible to detect quantitative trait loci (QTL), as well as their effects and positions on chromosomes, by new molecular and biometrical methods. A doubled haploid rapeseed population of 142 lines from the doubled winter rapeseed cultivars Mansholt's and Samourai, and a framework map derived from an RFLP map were used for the analysis of QTL and their interactions with N in terms of some yield components obtained from field trials in Brassica napus L. The interactions between traits and N were determined by variance analysis. Two QTL for number of seeds per pod, and four QTL for thousand seed weight were mapped at N0 (0 kg/ha N). Three QTL for pod length, two QTL for number of seeds per pod and three QTL for thousand seed weight were mapped at N1 (240 kg/ha N). All the QTL of N0 and N1 were mapped by analysing QTL x N interactions for all traits. Although it was found that there was no interaction between the mapped QTL and N, the results here can be used to improve the N-use efficiency and seed yield of Brassica napus.