Timing and method of 15nitrogen-labeled fertilizer application on grain protein and nitrogen use efficiency of spring wheat
2006
Ma, B.L. | Subedi, K.D. | Dwyer, L.M.
Grain protein content is one of the most important quality constraints for bread wheat (Triticum aestivum L.) production in eastern Canada. A field experiment was conducted for two years (1999 and 2000) on the Central Experimental Farm, Ottawa, Canada, to study whether split application of nitrogen (N) fertilizer improved grain protein content and nitrogen-use efficiency (NUE). Two cultivars ('Celtic,' as N-responsive and 'Grandin', as N-non-responsive) were grown using three different N doses and application methods: (1) 100 kg N ha(-1) as NH4NO3, soil-applied at seeding with 15N2-labeled NH4NO3 to microplots, (2) 60 kg N ha(-1) soil-applied at seeding plus 40 kg N ha(-1) foliar-applied at the boot stage with 15N2-labeled urea to microplots, and (3) 90 kg N ha(-1) as soil-applied at seeding plus 10 kg N ha(-1) foliar-applied at the boot stage with 15N2-labeled urea to microplots. Plants were sampled at heading and maturity. While dry-matter production and grain yields were not affected by the treatments in either year, N application methods influenced tissue N concentration and NUE. In 1999, extended drought stress led to significant yield reduction; in 2000, foliar application of 10 kg N ha(-1) at the boot stage significantly increased grain N concentration when grain protein was under the limit for bread quality, suggesting that later-applied N can contribute to grain protein content. At maturity, the average NUE was 22.3% in 1999 and 34.5% in 2000, but was always greater when all N was applied at seeding (42.5%) than when N was foliar-applied at the boot stage (18.5% to 24.5%). We conclude that application of a small amount of fertilizer N at the boot stage can improve the bread-making quality of spring wheat by increasing grain protein concentration.
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