Relation between Anthocyanin and Carbohydrate Concentrations in Seedlings of Benitade (Polygonum hydropiper L.)

Abstract

The relationship between anthocyanin and carbohydrate concentrations was examined in benitade (Polygonum hydropiper L.) seedlings grown in sand supplied only with water under different treatments of light or temperature.
Shading was provided by covering field grown seedlings with cheesecloth for 7 days after the unfolding of cotyledons. The lower the degree of shading, the higher the concentration of anthocyanin, reducing sugar and starch.
When seedlings were kept in a chamber and irradiated with blue, green or red light from fluorescent tubes (10.8-11.9J/m² sec, 12 hours per day) for 5 days after emergence, anthocyanin, reducing sugar and starch concentrations were highest in the seedlings irradiated with red light.
Seedlings were also grown for 9-10 days after the unfolding of cotyledons under outdoor plastic chambers at a constant temperature of 5, 15 or 25°C. Anthocyanin and reducing sugar concentrations were highest in seedlings grown at 15°C, but starch concentration was highest in seedlings grown at 25°C.
When the day temperature was controlled to 15, 20, 25 or 30°C, with a night temperature of 5°C, concentrations of anthocyanin, reducing sugar and starch increased as the day temperature decreased.
When seedlings were grown under night temperatures of 5, 10, 15 or 20°C, with a day temperature of 15°C, concentrations of anthocyanin and reducing sugar were higher at lower night temperature, although starch concentration was higher at 5-15°C than at 20°C.
In the above experiments, without added nitrogen, the concentration of nitrogen in seedlings was relatively low, and no relationship to anthocyanin concentration was found.
Combining the data from all the treatments described, and including results from previous nitrogen treatments (12), anthocyanin concentration was highly positively correlated with the concentration of reducing sugar or starch. However, reducing sugar concentration was negatively correlated with seedling fresh weight.
Spraying with glucose, fructose or sucrose solution (0.1M) increased the anthocyanin concentration of seedlings.
Promotion of anthocyanin synthesis in Polygonum seedlings seems to be closely correlated with a growth restriction, accompanied by the accumulation of carbohydrates such as sugar and starch.