Changes in Activity of Key Enzymes in Carbon-Nitrogen Metabolism of Different Flue-cured Tobacco Varieties at Mature Stage

In order to understand the rule of carbon-nitrogen metabolism of main flue-cured tobacco varieties in Nanxiong area,the author studied the changes in the activity of key enzymes in carbon-nitrogen metabolism of three flue-cured tobacco varieties( Yueyan 97,Yueyan 98 and K326) at mature stage. Along with the maturity of tobacco leaves,the total chlorophyll content,nitrate reductase activity,and invertase activity in the tobacco leaves of three varieties all showed a downward trend,while the amylase activity increased first and then decreased. The total chlorophyll content was the highest in Yueyan 98 and the lowest in Yueyan97 in earlier mature period,but the degradation rate of chlorophyll was higher in Yueyan 98 and lower in Yueyan 97. At earlier mature stage,the nitrate reductase activity of K326 and Yueyan 98 was very significantly higher than that of Yueyan 97. There were no significant differences in invertase activity and amylase activity among various flue-cured tobacco varieties in whole mature period.On the whole,the coordination of carbon-nitrogen metabolism of Yueyan 98 was relatively good.