Abstract:

The content of anthocyanin, soluble sugar and pH value in Cotinus coggygria leaves of four different types of leaf colors (“yellow”, “orange red”, “purple red”, “red”) were studied during the leaf color change in autumn of 2000. The results showed that the relative content of anthocyanin in all types increased at start and then decreased. All of them reached to a peak value on 24th October. The “purple red” type had the highest relative content of anthocyanin with 306.55 pigment units, while the “yellow” type had the lowest with 42.25 pigment units. The content of soluble sugar in each type had no significant difference and decreased during the leaf color change. The pH value of “purple red” was lower than that of “yellow” type, and the difference was significant (P<0.05). The pH value of green leaves was obviously higher than that of red leaves in the same tree. Of all the growth regulators applied in three years (1998, 1999, 2001), ethephon increased most the pigment of anthocyanin with the treated concentration of 500 mg·Ｌ^－１, and the content of chlorophyll in the leaves decreased slowly. It indicated that the ethephon of appropriate concentration is beneficial to extend the ornamental period of the colored leaves.

Key words: Cotinus coggygria, leaf color, anthocyanin, pH, ethephon