烟叶成熟过程中碳氮代谢关键酶对追施氮肥的响应

采用盆栽试验，通过测定烤烟成熟过程中叶片硝酸还原酶(NR)和转化酶(Inv)活性，研究了无机氮肥的追期和追量对烟叶成熟过程中叶片碳氮代谢强度及转化的影响，结果显示：在上、下部叶片成熟过程中，NR和Inv活性下降；随追氮时期推迟或追氮量增加，下部叶NR和Inv活性提高，Inv／NR降低，Inv／NR曲线峰值延后；在移栽后30d内或追氮量低于总施氮量30％时，随追氮时期推迟或追氮量增加，上部叶NR活性、Inv活性、Inv／NR降低。在本试验条件下，于移栽后30d追肥，追氮量30％，最有利于上、下部叶成熟过程中碳氮代谢的协调和适时转化。

Effect of Nitrogen Topdressing on the Key Enzymes of Carbon and Nitrogen Metabolism During the Process of Tobacco Leaf Maturation

The nitrate reductase and invertase activity were detected to study the effect of dressing on the level and conversion of carbon and nitrogen metabolism during the maturation of tobacco leaves by pot test. The results indicated that during the process of upper-leaf and lowerleaf maturing, the nitrate reductase and invertase activity decreased. With the postponing of topdressing stage and increasing of topdressing amount, the nitrate reductase and invertase activity of lower-leaf raised, Inv/NR decreased, and the transferring of curve was postponed. In 30 days of transplanting or when the topdressing amount was less then 30 percent of the total N fertilizer amount, the nitrate reductase and invertase activity and Inv/NR of upper-leaf decreased with postponing dressing stage or increasing N amount. In this test, it was 30 days after transplanting or 30 percent of N topdressing amount to the total N fertilizer amount that was propitious to corresponding and transforming of carbon and nitrogen metabolism during the process of upper-leaf and lower- leaf maturing.