| In order to understand the regulatory effect of topdressing nitrogen and planting density on high yield and high quality production of weak gluten wheat, a wheat variety Yangmai 15 was used as the material, and five nitrogen topdressing levels(0, 54, 48.6, 43.2 and 37.8 kg·hm-2, designated as N0, N1, N2, N3, and N4 respectively) and three planting densities(1.8×106, 2.4×106, and 3.0×106 plants·hm-2, designated as D1, D2, and D3, respectively) were set up. 15N tracer technique was applied to study the effects of different nitrogen topdressing levels and planting densities on yield, quality and nitrogen absorption and utilization of wheat. The results showed that the nitrogen accumulation of wheat plants at flowering stage, vegetative organs at maturity stage and grains at maturity stage decreased significantly with the decrease of nitrogen application rate in the range of 0~54 kg·hm-2, but increased significantly with the increase of planting density. The proportion of soil nitrogen in the accumulated nitrogen was greater than that of fertilizer nitrogen, and the proportion of topdressing nitrogen fertilizer was greater than that of basal nitrogen fertilizer. Under the conditions of D1, with the decrease of nitrogen application rate, the nitrogen fertilizer production efficiency, nitrogen fertilizer utilization rate, effective panicle number, and yield of wheat decreased significantly. Under the conditions of D2 and D3, with the decrease of topdressing nitrogen, the fertilizer nitrogen transport rate, nitrogen fertilizer production efficiency and yield all showed a trend of increasing first and then decreasing, and N2 was the largest. Under the same nitrogen topdressing amount, with the increase of planting density, nitrogen fertilizer production efficiency, nitrogen fertilizer utilization efficiency, panicle number, and yield increased significantly. Reducing nitrogen topdressing and increasing planting density reduced wheat grain sedimentation value, wet gluten content, and protein content, but increased starch content. Under the conditions of this experiment, the optimal planting density was 3.0×106 plants·hm-2, and the optimal nitrogen application rate was 48.6 kg·hm-2. Under the premise of ensuring the best quality of weak gluten wheat, it promoted the absorption and utilization of nitrogen fertilizer by wheat, and then synergistically improved nitrogen accumulation, grain yield and nitrogen production efficiency. |
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