Objective   Response of Impatiens uliginosa to copper ions on the floral color with respect of the physiological and biochemical properties of the petals was investigated.

  Method  Under treatments of varied Cu²⁺ concentrations (i.e., 0, 5, 10, 15, and 20 mg·L⁻¹) in culture medium, the chromaticity, pH of cell fluid, pigments, and basal metabolites of flower petals of the I. uliginosa at full blooming stage were determined. The correlations among Cu²⁺, physiological and biochemical indices, and flower color were analyzed.

  Result   (1) The contents of anthocyanins, flavonoids, and soluble sugars in petals decreased significantly in comparison to control as the Cu²⁺ concentration increased (P<0.05). (2) Soluble protein increased significantly over control with increasing Cu²⁺ at P<0.05. (3) In the range of 0-15 mg·L⁻¹, Cu²⁺ exerted no significant effect in the contents of carotenoids and proline. (4) There were extremely significant correlations among the color values, anthocyanins, flavonoids, soluble sugar, proline, and soluble protein of petals on the plants treated by Cu²⁺ at different concentrations. (5) The stepwise regression analysis showed that the flower chromaticity a* and b* were mainly affected by anthocyanins, soluble sugar and proline.

  Conclusion   Anthocyanin appeared to directly govern the color of I. uliginosa flowers. Cu²⁺ seemed to affect the petal color through regulating anthocyanin biosynthesis inI. uliginosa.