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Background <p>Optimizing nitrogen (N) application and planting density is a green and efficient agronomic strategy to increase crop yield and nitrogen use efficiency (NUE). However, the sesame responses to the interactive effects of N dose and planting density have not been fully elucidated. Here, we investigated the effects of different planting densities and N rates on the growth performances, physiological traits, N and carbon metabolism, yield components, and seed quality of two black sesame varieties (JHM and PYH). Two-year field experiments were conducted combining three planting densities (110,000, 160,000, and 330,000 plants.ha<sup>− 1</sup>) and three nitrogen rates (45, 90, and 135&#xa0;kg.ha<sup>− 1</sup>).</p> Results <p>Analyses revealed that sesame’s response to the combined effects of planting density and N rate is developmentally regulated and varietal-specific. Notably, we found that a moderate nitrogen dose of ≤ 90&#xa0;kg.ha⁻¹ coupled with dense planting of ⁓330,000 plants per hectare improved sesame growth, NUE, yield, and seed quality. This optimal planting condition significantly improved N allocation to seeds, maximized the yield of JHM and PYH to 3.47 t·ha<sup>⁻1</sup> and 3.84 t·ha<sup>⁻1</sup>, respectively, and considerably enhanced seed oil and unsaturated fatty acid contents. <i>AMT1</i> and <i>NRT2.13&#xa0;A</i> were identified as promising candidate regulatory genes of sesame NUE and modulators of N metabolism under dense planting density and moderate N rate. Other candidate N regulatory and sucrose metabolism-related genes were also identified.</p> Conclusions <p>This study exposes the complexity of mechanisms underlying sesame response to dual effects of planting density and N rate, and identifies a potential optimal planting condition to improving yield per unit area and seed quality. This agronomic optimization is likely to reduce environmental risk compared with high-N regimes. However, the proposed regime is optimal for the two tested varieties and the specific soil–climate conditions studied, and it should be validated in additional germplasm and environments before broader extrapolation. .</p>

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Physiological and molecular insights into nitrogen rate and planting density interactive regulation of black sesame nitrogen use efficiency, growth, yield, and seed quality

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月22日

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  • Min Wang,
  • Xuefei Tian,
  • Guangwei Wei,
  • Huiyi Yang,
  • Xiaohui Wang,
  • Xi Yang,
  • Sheng Fang,
  • Ziming Wu

摘要

Background

Optimizing nitrogen (N) application and planting density is a green and efficient agronomic strategy to increase crop yield and nitrogen use efficiency (NUE). However, the sesame responses to the interactive effects of N dose and planting density have not been fully elucidated. Here, we investigated the effects of different planting densities and N rates on the growth performances, physiological traits, N and carbon metabolism, yield components, and seed quality of two black sesame varieties (JHM and PYH). Two-year field experiments were conducted combining three planting densities (110,000, 160,000, and 330,000 plants.ha− 1) and three nitrogen rates (45, 90, and 135 kg.ha− 1).

Results

Analyses revealed that sesame’s response to the combined effects of planting density and N rate is developmentally regulated and varietal-specific. Notably, we found that a moderate nitrogen dose of ≤ 90 kg.ha⁻¹ coupled with dense planting of ⁓330,000 plants per hectare improved sesame growth, NUE, yield, and seed quality. This optimal planting condition significantly improved N allocation to seeds, maximized the yield of JHM and PYH to 3.47 t·ha⁻1 and 3.84 t·ha⁻1, respectively, and considerably enhanced seed oil and unsaturated fatty acid contents. AMT1 and NRT2.13 A were identified as promising candidate regulatory genes of sesame NUE and modulators of N metabolism under dense planting density and moderate N rate. Other candidate N regulatory and sucrose metabolism-related genes were also identified.

Conclusions

This study exposes the complexity of mechanisms underlying sesame response to dual effects of planting density and N rate, and identifies a potential optimal planting condition to improving yield per unit area and seed quality. This agronomic optimization is likely to reduce environmental risk compared with high-N regimes. However, the proposed regime is optimal for the two tested varieties and the specific soil–climate conditions studied, and it should be validated in additional germplasm and environments before broader extrapolation. .