Effects of Exogenous Amylases and Metal Ions on the Amylase Specific Activities and Starch Degradation of the Upper Leaves of 'KRK^sub 26^' during Flue-curing

The aim of this study was to investigate the effects of exogenous amylases and Car^sup 2+^, Mn^sup 2+^ and K^sup +^ on the amylase specific activities and starch degradation of the upper leaves of KRK^sub 26^ planted in Yunnan Province during flue-curing. The amylase specific activities and starch degradation of the leaves were determined by using spectrophotometry. The 8 U/g exogenous α-amylase could improve the specific activity of the leaf a-amylase at yellowing and color-fixing stages, but could not at stem-drying stage, and similarly, the 80 U/g exogenous β-amylase could improved the specific activity of the leaf β-amylase at the yellowing stage and the early period of color-fixing stage. The leaf starch could be enhanced to degrade by the exogenous α- or β-amylases and the enhancing effect of the former was stronger than that of the later. The 1.50 mg/mI Ca^sup 2+^ improved the specific activity of the leaf (α+β)-amylase mainly due to its enhancing effect on the leaf α-amylase, and increased the starch degradation.