烤烟基肥施用时间与氮肥利用的相关性研究

Effect of basal nitrogen fertilization time on nitrogen fertilizer use in flue-cured tobacco

烤烟是一种氮素敏感型的品质作物, 对氮素的需求非常严格。氮肥的合理施用不仅有利于提高烤烟对氮素养分的吸收利用, 也有利于提高烤烟烟叶品质。本研究采用大田试验的方法, 在湖北省烤烟主产区研究了基肥在3个不同施用时间（烤烟烟苗移栽前0 d、15 d和30 d）对烤烟氮肥利用参数的影响及其相关性。结果表明, 烤烟地上部烟叶和茎秆中干物质累积量和氮素含量均随着基肥施用时间的提前而表现出增加趋势。与移栽当天（0 d）施用基肥相比, 提前15 d、30 d施用基肥, 烤烟烟叶中干物质累积量和氮素含量分别平均增加16.4%、22.6%和1.5%、8.7%; 茎秆中则分别平均增加2.5%、12.7%和13.4%、33.9%。提前施用基肥有提高烤烟氮肥表观利用率的趋势, 但是各处理间差异不显著（P〉0.05）, 而在烤烟烟苗移栽前15 d、30 d施用基肥显著降低烤烟地上部氮肥农学利用率（35.2%、37.4%）和生理利用率（35.4%、41.6%）（P〈0.05）。另外, 基肥施用时间与氮肥农学利用率、生理利用率和偏生产力均表现出显著或者极显著负相关关系, 而氮肥农学利用率与生理利用率和氮肥偏生产力以及氮肥生理利用率与偏生产力之间均表现出显著或极显著正相关关系。因此, 在烤烟烟苗移栽时适当提前基肥的施用时间（15~30 d）有利于提高烤烟对氮素的吸收利用, 促进烟叶中干物质的累积。

Flue-cured tobacco （FCT） is a nitrogen-sensitive plant with strict requirements for nitrogen （N）. Reasonable application of N fertilizer not only favors N absorption and utilization as nutrient, but also improves tobacco leaf quality. A field experiment was carried out to determine the effects of basal N fertilization time （0 d, 15 d and 30 d before tobacco seedling transplant） on N use parameters by FCT plant in the main tobacco production area of Hubei Province. The results showed that dry matter accumulation （DMA） and N content in tobacco leaf and stem increased with earlier basal fertilization time. For basal fertilizer application times of 15 d and 30 d before seedling transplant, DMA/N content respectively increased by 16.4%/1.5% and 22.6%/8.7% in tobacco leaf and by 2.5%/13.4% and 12.7%/33.9% in tobacco stem. Basal fertilizer application time did not significantly （P 〉 0.05） influence N recovery efficiency. However, it significantly （P 〈 0.05） decreased agronomic N use efficiency by 35.2% and 37.4% and physiological N use efficiency by 35.4% and 41.6% respectively for basal fertilizer application times of 15 d and 30 d before seedling transplant. Furthermore, basal fertilization time was negatively correlated with agronomic N use efficiency, physiological N use efficiency and partial factor productivity of applied N. However, agronomic N use efficiency was positively correlated with physiological N use efficiency and partial factor productivity of applied N. Also physiological N use efficiency was positively correlated with partial factor productivity of applied N. In terms of N absorption and utilization and dry matter accumulation in tobacco leaf, it was advantageous to apply basal N fertilizer 15 d and 30 d before tobacco seedling transplant.