Abstract:

By optimising crop rotation patterns and nitrogen application regimes, changes in spring wheat yield and quality were explored to provide a scientific basis for establishing high-yielding, high-quality production practices on farmland. This study was conducted in the west oasis irrigation area of Gansu Province, and the trial was designed in a completely randomized group design. Four cropping patterns were established: wheat continuous crop (W), spring wheat-vicia sativa-spring wheat-vicia sativa (WV), spring wheat-winter wheat-vicia sativa (WWV) and spring wheat-winter rape-vicia sativa (WRV); three N levels were applied in the two-year crop rotation: without N (N₀), 25% reduction of 270 kg/hm² (N₁), and conventional application of 360 kg/hm² (N₂). The determination of dry matter accumulation, yield and quality of wheat was carried out to establish a reasonable cropping pattern and nitrogen application system for the region, and thus increase wheat productivity. The results showed that dry matter accumulation increased rapidly from nodulation to filling stage at different levels of N application, N₂ treatment had the highest dry matter accumulation at flowering stage, N₁ reduced by 10.1% and 10.6% compared to N₂ treatment; the three crop rotation patterns WRV, WWV and WV increased wheat dry matter accumulation by an average of 14.9%, 15.7% and 10.9%, and 11.8%, 8.6% and 8.1% in 2020 and 2022 compared to the continuous crop pattern. Under the reduced N treatment, wheat thousand grain weight, number of spikes per unit area and number of grains per spike were reduced, but the crop rotation pattern increased thousand grain weight, number of spikes per unit area, number of grains per spike, and yield. Yields were reduced by 11.5% and 12.5% in the N₁ treatment compared to the N₂, and increased by 18.5% and 23.8%, 10.3% and 16.1%, 6.0% and 11.5% in the WRV, WWV and WV rotations, respectively, compared to the continuous crop pattern. The crop rotation pattern combined with N fertilizer could effectively improve the quality of the seeds, where the seed protein content, sedimentation value and wet gluten content were enhanced. Correlation analysis showed that the crop rotation pattern combined with nitrogen fertilization had an enhancing effect on crop yield, which was mainly due to the synergistic increase in yield components. At the different nitrogen application level, the spring wheat-winter rape-vicia sativa rotation pattern had a significant effect on the yield and quality of farmland spring wheat. Therefore, it could be used as a new cropping pattern to improve the yield and quality of farmland wheat in the northwest oasis irrigation area.

Key words: spring wheat, nitrogen application level, cropping pattern, dry matter, seed quality