Chin J Plant Ecol ›› 2007, Vol. 31 ›› Issue (4): 673-679.DOI: 10.17521/cjpe.2007.0087

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WANG Zheng-Wen()   

  1. Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2006-08-03 Accepted:2007-01-05 Online:2007-08-03 Published:2007-07-30
  • Supported by:
    National Natural Science Foundation of China(30370268);Knowledge Inovat ion Programs of the Chinese Acadeny of Sciences(KZCX2-XB2-01)


Aims This study of the rhizomatous clonal grass Leymus chinensis examines: 1) temporal variations of water-soluble carbohydrate (WSC) in shoots and rhizomes and their responses to defoliation; 2) WSC concentrations in different plant parts at specific growth stages; 3) links between variations of WSC concentration in aboveground shoots, belowground shoots and rhizomes; and 4) the significance of carbohydrate reserves for the growth and survival of ramets and the whole genet of the plant.
Methods A control (intact) and three treatments as one, three and five defoliations were used in a field experiment. All defoliations left plants 15 cm high. Shoots and rhizomes were sampled in different quadrats every 10 days. WSC carbohydrate concentrations in different plant parts were determined with HPLC (high performance liquid chromatography). ANOVA was used to detect differences among treatments in temporal dynamics of WSC contents.
Important findings The marked reduction of WSC concentration in the control in a stage of rapid growth was attributed to higher growth rate and thus higher respiration rate in the carbon metabolism of leaves, while WSC concentrations in defoliation treatments were less reduced or increased under frequent defoliation, mainly due to reduction of total respiration with leaf loss. Single defoliation did not affect the final WSC concentration in aboveground shoots, but successive defoliations did. The more frequent the defoliations, the more rapid the transfer of carbohydrate from aboveground shoots to belowground shoots or rhizomes in response to declining air temperature. WSC concentrations in belowground shoots were slightly more stable than in aboveground shoots, probably because belowground shoots functioned as storage organs for tiller buds and partly for some nutrient or assimilate. WSC in rhizomes must be transported into aboveground shoots to supply them, and intensive growth depletes WSC; however, such depletion can be mitigated when clonal integration in intact neighborhood ramets results in replenishment of defoliated ramets (usually at the frequent defoliation treatment).

Key words: defoliation, Leymus chinensis, storage, water-soluble carbohydrate