Effect of nitrogen fertilization and soil relative water content after anthesis on nitrogen absorption and translocation of black wheat

Black wheat variety ‘Luozhen 1’, a colored wheat variety, was higher in nutritional value and exploring potential. However, its low yield was the main limiting factor of plantation due to weak photosynthetic capacity and matter translocation ability at key stages of yield forming. In order to provide the theory basis for high yield cultivation of black wheat, a pot experiment was carried out to study the effect of nitrogen rate and soil relative water content after anthesis on nitrogen absorption and translocation of black wheat ‘Luozhen 1’ at the station of the Institute of Crop Science of Chinese Academy of Agricultural Sciences in 2014–2015. Two factors were set in the experiment, nitrogen fertilization rate 150 kg(N)?hm^-2 (low N level, N₁), 240 kg(N)?hm^-2 (middle N level, N₂), 330 kg(N)?hm^-2 (high N level, N₃) and soil relative water content after anthesis 75%85% (adequate water supply treatment, W₁), 55%65% (middle water stress, W₂) and 35%45% (serious water stress, W₃) of field capacity. The results showed that grain nitrogen content and protein accumulation amount declined with decreasing soil relative water content under the same nitrogen fertilization rate. Protein components contents varied with different nitrogen fertilization rates and soil relative water content. The contents of albumin, globulin and prolamin increased with declining soil water content in low N level (N₁). In high N level (N₃) treatment, albumin and globulin contents also increased with declining soil water content, while prolamin content decreased. Under soil water stress conditions (W₂, W₃), nitrogen content, protein accumulation amount in seeds increased and the percentage of grain nitrogen content at maturity declined with increasing nitrogen fertilization rate. However, under adequate water supply (W₁), protein accumulation amount, nitrogen translocation efficiency from nutritive organs to grain and nitrogen translocation amount were highest under middle N level (N₂). Albumin, globulin and prolamin contents also increased with increasing nitrogen fertilization rate under W₁ condition, while glutenin reached the highest level in N₂ treatment. Under water stressed conditions (W₂ or W₃), all protein components were highest in N₂ treatment. It was concluded that there were significant impact of nitrogen rate and soil water content after anthesis on nitrogen metabolism of black wheat ‘Luozhen 1’. Nitrogen application rate of 240 kg?hm^-2 and adequate water supply were recommended in the experimental condition due to effective nitrogen metabolism process.