Chin J Plant Ecol ›› 2007, Vol. 31 ›› Issue (4): 599-606.DOI: 10.17521/cjpe.2007.0076

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CAI Ying1,2, GUAN Bao-Hua1,2, AN Shu-Qing1,2,*(), SHEN Rui-Ling2, JIANG Jin-Hui2, DONG Lei3   

  1. 1The State Key Laboratory of Pollution Control and Resource Reuse, School of Life Science, Nanjing University, Nanjing 210093, China
    2Institute of Wetland Ecology, Nanjing University, Nanjing 210093, China
    3South China Botany Garden, Chinese Academy of Sciences, Guangzhou 510650, China
  • Received:2006-07-19 Accepted:2007-01-05 Online:2007-07-19 Published:2007-07-30
  • Contact: AN Shu-Qing


Aims Trapa bicornis is a clonal floating macrophyte that dominates several lakes in China. Due to eutrophication, the distribution of T. bicornis is shrinking, and T. bicornis has disappeared in some lakes. Our objectives were to investigate the effects of sediment phosphorus concentration (SP), plant density (PD) and their interaction on the plasticity of T. bicornis and examine whether plasticity could promote ecological adaptation in eutrophic environments.
Methods In a controlled factorial experiment, we grew artificial populations of T. bicornis in low, medium and high PD (4, 8 and 12 individuals per container, respectively) under low, medium and high SP. We harvested all plants after six weeks and measured the dry mass for each plant part.
Important findings SP significantly affected leaf, stem, green root, anchoring root and total plant phosphorus concentrations as well as number of main rosettes of trullate floating leaves, special green root length and special anchoring root length of T. bicornis, but PD did not significantly affect any growth or ecophysiological traits. With increasing SP, plant phosphorus concentration increased. Number of main rosettes of trullate floating leaves of T. bicornis was the largest at low SP and low PD, leaf mass ratio at medium SP and high PD, special green root length at high SP and medium PD, and special anchoring root length at high SP and high PD. SP, PD and their interaction altered some of the allometric relationships between leaf, stem, green root, anchoring root and total biomass. Morphological and ecophysiological traits mostly affected by SP and high PD may increase the ecological adaptability of T. bicornis under eutrophic conditions caused mainly by phosphorus.

Key words: phenotypic plasticity, sediment P concentration, plant density, Trapa bicornis, clonal plants, ecological adaptability