关键词: 氮素积累, 氮素利用, 氮素转运, 籽粒氮素积累特征, 不同产量水平麦田, 籽粒产量, 小麦

Abstract:

【Objective】 Improving the nitrogen transport and accumulation of nutrient organs after wheat flowering, as well as improving the nitrogen accumulation characteristics of wheat grains, is beneficial for increasing the nitrogen accumulation and yield of wheat. This study aimed to clarify the physiological mechanisms underlying the differences in nitrogen utilization efficiency among wheat plants at different yield levels, so as to provide a theoretical basis for reducing yield differences and improving nitrogen utilization efficiency and to achieve high yield and efficient production of wheat.【Method】 The field experiments were conducted in Shiwang Village, Xiaomeng Town, Shandong Province for two consecutive years from 2020 to 2022. Using Tobacco Farmer 1212 as the planting material, three yield levels of wheat fields with a perennial winter wheat yield of around 10 500 kg·hm^-2 (S), 9 000 kg·hm^-2 (H), and 7 500 kg·hm^-2 (M) were selected to compare and analyze the differences in plant nitrogen accumulation and transport, grain nitrogen accumulation characteristics, and grain yield in wheat fields with different yield levels.【Result】 Compared with H and M wheat fields, S wheat field significantly increased the number of spikes per unit area and thousand grain weight, with grain yield 19.64%-27.91% and 51.68%-80.87% higher than H and M wheat fields, respectively, resulting in the highest nitrogen absorption efficiency, nitrogen partial productivity and nitrogen harvest index. The nitrogen accumulation in the nutrient organs of S wheat field during the flowering period increased by 14.22-42.11 kg·hm^-2 and 53.74-103.16 kg·hm^-2, respectively. The nitrogen accumulation in mature nutrient organs was S, H>M. Compared with H and M wheat fields, S wheat field significantly increased the nitrogen transport of pre flowering nutrient organs and nitrogen accumulation after flowering, and increased the contribution rate of nitrogen accumulation in post flowering nutrient organs to grains, thereby achieving the highest nitrogen accumulation in mature grains. The S wheat field significantly increased the content of free amino acids and soluble proteins in flag leaves after flowering, for promoting the inter source sink transport of nitrogen. According to the logistic equation fitting, the S wheat field significantly increased the maximum and average accumulation rates of grain nitrogen, prolonged the duration of grain nitrogen accumulation, and was the main reason for obtaining the highest grain nitrogen accumulation.【Conclusion】 Suitable soil environment in S wheat field could promote the transfer of stored nitrogen from vegetative organs to grain, and increase the rate of grain nitrogen accumulation and prolong the duration of grain nitrogen accumulation, which was the main reason for the highest grain yield and nitrogen use efficiency.

Key words: nitrogen accumulation, nitrogen utilization, nitrogen translocation, characteristics of grain nitrogen accumulation, wheat fields with different yield levels, grain yield, wheat