Seeding rate and nitrogen management effects on spring wheat yield and yield components
Seeding rate, N level, and N application timing are key management factors for spring wheat (Triticum aestivum L.) production in North Dakota. Experiments were conducted under dryland (Casselton, ND) and irrigated (Carrington, ND) conditions in 2003 to 2005 to determine the optimum combination of seeding rate and N management to maximize yield of hard red spring wheat (HRSW). Treatments consisted of a factorial combination of HRSW genotypes (‘Briggs’, ‘Alsen’, ‘Granite’, and ND 740), seeding rates (2.9 and 4.2 million seeds ha–1), N levels (140 and 224 kg ha–1 for the dryland site; 168 and 280 kg ha–1 for the irrigated site), and N application timing (preplant, two-split, and three-split). Nitrogen level, N timing, and seeding rate showed no significant effect on grain yield across environments. However, genotype significantly influenced grain yield. Increasing seeding rate failed to increase grain yield of the three cultivars, but ND 740 was most productive at the lowest seeding rate. Increasing the level of N significantly increased grain protein content (GPC) over all environments. Grain volume weight (GVW) and thousand kernel weight (TKW) decreased with increasing N level and were influenced by genotype. Increased seeding rate significantly increased plant stand and tiller number while increasing N levels significantly increased head count. These data indicate that although genotype was the primary factor in determining grain yield, GPC, and agronomic traits, individual genotypes responded differently to varying seeding rates and N management practices.