Abstract:

The effect of the activity of amylase and starch phosphorylase on the starch degradation in tobacco leaves under different temperatures and humidities were studied using the middle leaves of flue-cured tobacco in cultivar’s HD and K326. The result indicated there were two peaks of activities for amylase and starch phosphorylase during flue-curing. The first was at middle stage of yellowing, and the other one was at the beginning of fixing-color. Starch degradation in tobacco leaves was concentrated in the period of yellowing, and slowed down in the earlier stage of fixing-color, then nearly stopped from later stage of fixing-color to the end of flue-curing. The quantity and the velocity of starch degradation, the activities of amylase and starch phosphorylase were relatively high, the content of starch was lower, while the content of soluble sugar and reducing sugar were higher and all of the chemical components were relatively harmonized in the cured tobacco leaves yellowed under lower temperature and humidity and fixed color with slow heating speed.

Key words: Flue-cured tobacco, Temperature and humidity, Starch degradation enzyme