Variation of delta super(13)C in Aegiceras corniculatum seedling induced by cadmium application

To test whether the values of delta super(13)C in mangrove plants are affected by Cd application, the seedlings of Aegiceras corniculatum, a dominant mangrove species, were cultured in soil supplied with CdCl sub(2) solution at the concentration of 0, 0.5, 2.5, 5, 20, 30 and 50 CdCl sub(2) mg/kg wet soils. Plants were grown in 10 replicate pots with 5 propagules each. After 5 months of Cd exposure, three pots contained 15 seedlings with average shoot heights were selected for each treatment. Leaves and roots of seedling were sampled respectively and analyzed for delta super(13)C. Growth traits (fresh weight, shoot height and root length), total chlorophyll content, and Cd concentrations in leaf, root and dry soil were determined. After 5 months of the seedling growth, the concentrations of Cd in dry soil were 0.47, 0.83, 2.77, 4.54, 18.89, 29.79 and 47.35 mg/kg respectively. The values of delta super(13)C in roots and leaves were affected to some extent by Cd application. Although root delta super(13)C showed more sensitive to Cd compared with leaves, the values of delta super(13)C in roots were not significantly affected by Cd until Cd level higher than 29.78 mg/kg which was not expected to exist in natural environments. Minor variation in delta super(13)C values observed in roots and leaves was likely due to limited Cd uptake by seedlings and subsequent lack of negative impacts on photosynthesis.