Norstar winter wheat (Triticum aestivum L.) was examined in 11 trials with the objective of determining the pattern of dry matter and nitrogen (N) accumulation in dryland stubbled-in winter wheat grown in Saskatchewan. In all 4 yr of this study, replicated no-till field trials were supplemented with 0, 34, 67 and 100 kg N ha−1 applied as ammonium nitrate (34-0-0) in early spring. A fifth treatment of 200 kg N ha−1 was evaluated in the final year of trials. Plant samples were collected at 2-wk intervals. Early season N uptake was more rapid than dry matter accumulation and 89% of the total N, compared to 70% of the total dry matter, was present at anthesis (Zadoks growth stages 60–68). Poor soil moisture availability limited N uptake after anthesis. Consequently, N uptake during the growing season was best described by a quadratic equation, Nitrogen yield = −29.1 + 3.02 Z − 0.018 Z2, where Z represents the Zadoks growth stage. Nitrogen concentrations of the stems and leaves decreased during the growing season while the N concentration of spikes varied among trials. Nitrogen fertilization often produced large increases in tissue N concentration at the beginning of the growing season. These differences decreased with time and by the end of the season tissue N concentrations were usually similar for all N rates. In general, when residual soil N levels were low to intermediate and rainfall was adequate, N fertilization increased dry matter yield, plant N yield, grain yield and grain protein yield. Nitrogen fertilization increased plant N concentration, plant N yield, grain protein concentration and grain protein yield when soil N reserves were intermediate to high and rainfall was adequate.Key words: Nitrogen uptake, wheat (winter), nitrogen response, tissue nitrogen, grain protein, environment
In Winter Wheat, No-Till Increases Mycorrhizal Colonization thus Reducing the Need for Nitrogen Fertilization
