氮肥和密度对毯状苗移栽油菜碳氮积累、运转和利用效率的影响

【目的】研究油菜育秧盘毯状苗移栽,大田不同氮肥和密度耦合对油菜碳氮积累、运转和利用效率的影响,探讨植株碳氮代谢与油菜产量形成的关系。【方法】以宁杂1818油菜品种为试验材料,通过毯状苗的培育和移栽试验,比较不同年份、氮肥以及密度条件下碳氮积累、运转以及利用效率差异。【结果】油菜毯状苗适宜条件下移栽也可以获得3 750 kg·hm~(-2)高产。不施氮肥以及225 kg·hm~(-2)氮肥处理条件下随着密度增加产量显著增加,在300 kg·hm~(-2)氮肥处理和125 000穴/hm~2移栽密度条件下1穴1株、1穴2株和1穴3株间产量无显著差异。油菜植株中碳素积累能力显著高于氮素积累能力,初花期前植株C/N比较低,为16.30,初花期后C/N比较高,为114.37。碳素籽粒生产效率、氮素籽粒生产效率随着氮肥用量增加呈下降趋势,其中氮素籽粒生产效率随施氮量增加下降幅度更大。初花期至成熟期叶片氮素运转率最高,不同处理变化范围为73.90%—78.56%,其次是茎枝氮素运转率,变化范围为38.96%—67.08%,根中氮素运转率最低,变化范围为24.45%—37.06%。不同处理叶片中氮素运转率差异较小,茎枝和根中氮素运转率随着氮肥用量增加逐渐降低。初花期至成熟期叶片碳素运转率为正值,不同处理变幅为23.16%—29.08%,随着密度增加叶片碳素运转率总体上呈增加趋势,不同氮肥处理间差异相对较小。初花期至成熟期根和茎枝仍然以积累碳素为主,两者碳素运转率表现为负值。【结论】油菜毯状苗机械移栽,可有效提高茬口较迟地区的油菜生产能力。油菜在初花期之前氮代谢能力强,初花期以后碳代谢能力强,前期氮素供应有利于植株营养体的建成,从而使得后期积累更多的碳素,促进后期的产量形成。

Effects of Nitrogen and Planting Density on Accumulation,Translocation and Utilization Efficiency of Carbon and Nitrogen in Transplanting Rapeseed with Blanket Seedling

【Objective】 In order to discuss the relationship between carbon (C) and nitrogen (N) metabolism and yield in transplanting rapeseed with blanket seedling, the effects of different N application rates and planting densities on accumulation, translocation and utilization efficiency of carbon and nitrogen were studied. 【Method】 In this study, Ningza 1818 was planted by artificial transplanting with blanket seedling. The differences of C and N accumulation and translocation rates before and after flowering period, carbon utilization efficiency for grain production (CUEg) and nitrogen utilization efficiency for grain production (NUEg) under different years, nitrogen application rates and densities were studied. 【Result】The results showed that transplanting rapeseed with blanket seedling could obtain high yield (3 750 kg·hm^-2) under suitable conditions. The yield increased significantly with increased densities under 0 and 225 kg·hm^-2 N rates. There was no significant difference among 1 plant per spot, 2 plants per spot and 3 plants per spot with 125 000 spots/hm² transplanting density under 300 kg·hm^-2 N rate. The ability of C accumulation was significantly higher than that of N accumulation in rapeseed. The average C/N ratio before and after the early flowering period was 16.30 and 114.37, respectively. The CUEg and NUEg were declined with the increased N application, and the decline rates of NUEg were higher than those of CUEg. From the flowering period to the ripening period, the N translocation rate of the leaf was the highest, while that of the stem and the root ranked the second and the last, respectively. The N translocation rate of the leaf, stem and root from the flowering period to the ripening period ranged from 73.90% to 78.56%, 38.96% to 67.08% and 24.45% to 37.06% under different treatments. The differences of the N translocation rates of the leaf were slight, whereas those of the stem and root increased with increased N rates. From the flowering period to the ripening period, the C translocation rates of the leaf were positive values, which ranged from 23.16% to 29.08%. It increased generally as the N rates increased, and the differences resulted from N treatments were slight. From the flowering period to the ripening period, the root and the stem still accumulated C, and the C translocation rates of the root and the stem were negative values.【Conclusion】In the areas with the late harvest date of former crops, mechanical transplanting technology with blanket seedling could improve the production capacity of rapeseed. The ability of N metabolism before flowering was higher than that of after-flowering period while the ability of C metabolism had an opposite trend. N supply at early stage was conducive to form nutrition framework, which promoted the accumulation of C and yield formation from the flowering period to the ripening period.