| Abstrakt: |
Aims: Nitrogen (N) fertilizer application greatly enhances grain yield by improving dry matter accumulation and grain filling in winter wheat. However, the regulation mechanism of N rates on dry matter accumulation, transportation, and grain filling in winter wheat under dry farming could be more precise. Methods: Five N treatments viz. 0, 75, 150, 225, and 300 kg·N·ha−1, designated as N0, N75, N150, N225, and N300, were tested in two growing seasons of 2017–18 and 2018–19. Results: Fertilization significantly increased dry matter accumulation and intensity and assimilated accumulation after anthesis and its contribution to grain yield. N fertilizer significantly improved the superior and inferior grain weights, with the highest at N225, and increased by 22.29% and 24.41% in 2017–18 and 22.06% and 12.68% in 2018–19, respectively, compared to N0 (P < 0.05). Moreover, N fertilization increased the initial grain-filling potential and mean filling rate, shortened the days achieving the maximal grain-filling rate. N fertilizer increased the filling rate in the three periods, shortening the duration of the first-middle period, prolonging the late period, and increasing the contribution of the mid-late filling period to grain weight. However, excessive N application led to a reduction in the filling rate for each period. It prolonged the duration in the mid-late periods, which was not conducive to further increases in grain weight. Conclusions: The N225 can be a more suitable N fertilizer for improving the accumulation and transfer of dry matter, promoting grain-filling, and increasing wheat yield in dry farming in the Loess Plateau. [ABSTRACT FROM AUTHOR] |
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