Effects of Nitrogen Application Rate and Irrigation Amount on Stem Lodging Resistance and Yield of Rapeseed

The Brassica napus variety Qingza No.15 was used as the test material, and four nitrogen application levels (N₀: 0 kg/667 m², N₁: 5 kg/667 m², N₂: 10 kg/667 m², N₃: 15 kg/667 m²) and four irrigation levels (W₀: 120 m³/667 m², W₁: 102 m³/667 m², W₂: 84 m³/667 m², W₃: 66 m³/667 m²) were set up. The agronomic traits, mechanical properties, biochemical components and yield of rapeseed plants were compared and analyzed. The effects of different nitrogen application rates and irrigation amounts on lodging resistance and yield of rapeseed were studied. The results showed that the nitrogen application rate was 10 kg/667 m² and the irrigation amount was 84 m³/667 m² in the treatment of medium nitrogen and medium water (N₂W₂). Compared with N₀W₀, the flexural strength, compressive strength and puncture strength increased by 113.70%, 28.68% and 47.10%, respectively. The plant height, stem diameter and gravity center height increased by 20.55%, 72.21% and 12.49%, respectively. The content of cellulose and lignin increased by 15.74% and 16.28%, respectively. The yield increased to 161.93 kg/667 m², the lodging index decreased by 20.00%, and the lodging resistance was significantly improved. In summary, under the conditions of this experiment, the treatment mode of medium nitrogen and medium water (nitrogen application rate of 10 kg/667 m² + irrigation amount of 84 m³/667 m²) can significantly improve the utilization efficiency of water and fertilizer in rapeseed, improve the lodging resistance of plants while ensuring the yield, and achieve the goal of water saving and yield increasing.