Nitrogen Use Efficiency in a Genetically Diverse Set of Winter Oilseed Rape (Brassica napus L.)

Abstract

Genetic variation in N uptake and utilization was investigated in a set of genetically diverse oilseed rape (Brassica napus L.) genotypes, including hybrid, modern, and old cultivars and resynthesized lines. A total of 36 genotypes were grown at seven locations with two levels of N supply: no fertilization and optimal fertilization (between 160 and 220 kg ha(-1) N, depending on regional recommendations). The hybrid cultivars had the highest yields and the old land races and resynthesized lines had the lowest yields. This ranking of the various groups was consistent and independent of the N level. Genetic variation exists for both the uptake efficiency and the utilization efficiency. In the presence of low N levels, variation in N use efficiency is mainly due to differences in uptake efficiency whereas differences in utilization efficiency were more important in the presence of high N fertilization.