It was demonstrated that the Dumas method is suitable to analyse single kernel barley samples for their total nitrogen content directly without milling. The method was compared to the nitrogen analysis in milled samples over a range of 1.5-3.0 %N. These samples consisted of kernel size grading fractions from barley cultivated at different N-dressings and using a shading regime. A good correlation was found between milled and whole barley kernels (r(2)=0.852). The method was used to determine the nitrogen content of individual kernels in the barley grading fractions. The nitrogen content in these fractions decreased with increasing kernel size depending on growth conditions. A large variation in nitrogen content between individual kernels was found for all grading fractions. In a study of barley main spikes the variation in kernel nitrogen content within spikes was smaller than the variation between spikes, especially when the barley was grown at a 60% tight reduction regime during the kernel filling period. The average kernel total nitrogen content under the latter condition was about two times as high as in the control experiment. The kernel position along the spike did not clearly affect its nitrogen content. Acid and SDS polyacrylamide get electrophoresis (PAGE) revealed similar banding patterns for proteins from kernels at different positions of both low and high hi barley spikes. The single kernel method for nitrogen may be used by the breeder as a quality criterion for new barley varieties to test their spike development at different cultivation conditions. It can suit the maltster to screen rapidly the homogeneity in nitrogen (protein) content of barley batches.
