Seed, Oil, and Protein Yields of Canola under Combinations of Irrigation and Nitrogen Application
2011
Hamzei, Javad
Canola (Brassica napus L.), an important oilseed crop in Iran, is intensively managed with high inputs of N and irrigation water. Understanding N and water use characteristics of canola will help improve N and water use efficiency (WUE) and reduce production costs. Here, the effects of irrigation levels (IL₁, 750; IL₂, 450; and IL₃, 300 mm water ha⁻¹) and N rates (NR₁, 0; NR₂, 40; NR₃, 80; NR₄, 120; and NR₅, 160 kg N ha⁻¹) on canola production are evaluated during 2006 and 2007 growing seasons. Data showed that irrigation levels and N rates and their interaction had significant effects on WUE for seed, oil, and protein as well as seed, oil, and protein yields/ha. The maximum values of seed, oil, and protein yields ha⁻¹, WUE for these traits and seed weight plant⁻¹ were achieved at IL₂ × NR₄ treatment. The highest values of seed N concentration and seed N uptake were produced at IL₂ treatment. Among N rates, maximum averages of seed and straw N concentration were observed at 160 kg N/ha. The highest significant value of straw N uptake was observed at IL₁ treatment. Also, maximum N uptake for both seed and straw was the same at 120 and 160 kg N ha⁻¹. Total N uptake achieved significantly in IL₂ × NR₄ treatment. With decreasing irrigation water and increasing N rates, N use efficiency decreased significantly. In general, consumption of 450 mm water ha⁻¹ season⁻¹ and supplying 120 kg N ha⁻¹ can produce the highest seed, oil, and protein yields ha⁻¹, while increasing WUE and decreasing N leaching.
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