Abstract: [Objective] In this study, effects of different barking treatments on secondary metabolites of Eucommia ulmoides and its ability of repairing injury were investigated to provide a reference for rational utilization the trees. [Method] The content of the soluble sugar, malonaldehyde (MDA), free proline (Fpro), chlorogenic acid, total flavone, geniposidic acid and the activity of phenylalnine ammonialyase (PAL) in leaves of E. ulmoides were tested over 116 days after treatments with 50%, 75% and 100% barking. [Result] Under different barking treatments, the content of soluble sugar in E. ulmoides leaves showed a trend of first increasing and then decreasing to a stable level; except for 21 days and 36 days, 50% barking and 75% barking did not significantly change the soluble sugar content in leaves(P>0.05); after 36 days, 100% barking obviously led to an increase in soluble sugar content, by 1.3-fold of the control. Different barking treatments remarkably led to an increase in Fpro content, among them, 100% barking was obviously higher than that in the control before 86 days, had no significant difference with control after 86 days (P<0.05). As the barking degree increased, the MDA content showed a trend of first increasing and then decreasing in E. ulmoides leaves, the MDA content reached maximum value in 21 days after barking treatments. The results showed that different barking treatments all significantly increased the PAL activity in leaves, the maximum activity of PAL was reached in 21 days, and by then the 50%, 75% and 100% barking treatments increased the PAL activity by 2-fold, 2.1-fold and 2.6-fold of the control, respectively. The PAL activity showed a trend of decline with different treatment after 21 days. With different barking treatments, the content of chlorogenic acid in leaves had two peaks in 21 days and 56 days, and 75% barking treatment was obviously higher than other barking treatments and control (P<0.05), while the content of chlorogenic acid declined significantly after 56 days. The content of total flavone in leaves significantly increased under the different treatments(P<0.05), the content of total flavone reached maximum value in 21 days after barking treatments, and by then the 50%, 75% and 100% barking treatments increased the value of total flavone by 1.2-fold, 1.3-fold and 1.9-fold of the control. After 41 days, the content of total flavone had no significant difference with control(P>0.05). The content of geniposidic acid in leaves had the similar dynamics with chlorogenic acid, two peaks occurred in 21 days and 56 days. In 56 days, the content of chlorogenic acid in leaves was much higher than 21 days, and 75% barking treatment obviously led to an increase in content of geniposidic acid. However the content of geniposidic acid had no significant difference with control after 116 days(P>0.05).[Conclusion] It appears that barking treatments do harm to E. ulmoides to some degree, but the harm could be repaired after its comprehensive regulations. The 75% barking treatments in E. ulmoides is an optimal choice and secondary metabolites in the leaves of E. ulmoides could reach maximum values.

Key words: Eucommia ulmoides, barking, resistance, osmotic adjustment substances, secondary metabolites