The N, B and Nicotine content in tobacco leaves drop significantly in the order of top leaves, middle leaves and bottom leaves, while K, Fe and Reducing Sugar increase significantly in the same order;

氮、硼、烟碱含量从上部烟叶到下部烟叶显著地依次降低，而钾、铁、还原糖则从上部烟叶到下部烟叶显著地依次升高；

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The N, B and Nicotine content in tobacco leaves drop significantly in the order of top leaves, middle leaves and bottom leaves, while K, Fe and Reducing Sugar increase significantly in the same order;

氮、硼、烟碱含量从上部烟叶到下部烟叶显著地依次降低，而钾、铁、还原糖则从上部烟叶到下部烟叶显著地依次升高；

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