不同施氮水平和氮素来源烟叶碳氮比及其与碳氮代谢的关系

C/N of Tobacco Leaf and Its Relations with Carbon and Nitrogen Metabolism as Related to Nitrogen Level and Source

研究表明，烟叶在发育和成熟过程中碳氮比逐渐增加并表现一个快速增长期，随着施氮水平的增加而趋于推迟和不明显。烟叶烘烤后碳氮比有所下降。烟叶碳氮比变化与含氮量相关性大于含碳量，后者在烟叶发育过程中变幅较小，但在施氮水平低时，表现由升到降的变化。烟叶C／N与NR活性、蛋白酶活性、蛋白质含量、还原糖含量、烟碱含量有密切关系，且随着叶片发育和成熟，相关系数加大，大于总施氮量、无机氮施量和有机氮施量与它们的相关性。后期C／N与碳氮代谢物质的相关性表现为：NR活性＞蛋白质含量＞还原糖含量＞烟碱含量。烟叶发育和成熟过程中NR活性和蛋白质含量降低，烟碱和还原糖含量升高，但在不同施氮水平和氮素来源下其变化模式有显著差异。在同一施氮水平下有机氮和无机氮适当配比，有利于调节C／N和碳氮代谢。

In the process of tabacco leaf development and mature, the ratio of C to N increased gradually and had a rapid increasing period which arrived later and became less obvious as the nitrogen aplly lowers. The value of C/N became smaller after flue-curing. The correlation between C/N and N content was greater than that between C/N and C content, which was more stable during the leaf development. The C/N value nad a close relationship with NR, proteinase activity, and protein, nicotine, reducing sugar contents,and the correlation coefficents becarne greater as leaf developed and matured,which was larger than that between C/N and total N applied,organic N applied, inorganic N applied respectively. In later period, the correlation nature with C/N was: NR activity>rpotein content>reducing sugar content>nicotine content. In the process of leaf development and mature, NR activity and protein content decreasded, yet nicotine and reducing sugar contents increased, but the changing models were significantly different under varying N levels and N resources. At a certain level of N applied, the mixing of organic N and inorganic N in proper proporition can regulate C/N and carbon nitrogen metabolism.