Chin J Plant Ecol ›› 2007, Vol. 31 ›› Issue (4): 658-664.DOI: 10.17521/cjpe.2007.0085

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ZHU Ya-Juan1,2, ALATEN Bao1,3,4, DONG Ming1, HUANG Zhen-Yin1,*()   

  1. 1Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2Graduate University of Chinese Academy of Sciences, Beijing 100049, China
    3 Graduate School of Beijing Forestry University, Beijing 100083, China
    4Ordos Forestry Department, Dongsheng, Inner Mongolia 017000, China
  • Received:2006-07-29 Accepted:2007-11-05 Online:2007-07-29 Published:2007-07-30
  • Contact: HUANG Zhen-Yin


Aims Hedysarum laeve is a rhizomatous perennial semi-shrub, which reproduces both sexually and clonally in natural populations. Study of reproduction trade-off of this species could provide theoretical foundation for the management of natural grassland. The specific goal of this study was to determine if there is a trade-off between sexual and clonal reproduction in H. laeve natural population in response to water and nutrient supplies.
Methods During the growing season of June to September 2005, we conducted two field experiments in Mu-Us Sandland using 1 m×1 m plots. Different amounts of water were added to the plots to imitate 0, 16, 32 and 64 mm of precipitation. Nutrient additions were 0, 30, 60, 90 and 120 g. The biomass of H. laeve ramets in each plot was measured in late September 2005.
Important findings Increasing water supply decreased both biomass and biomass allocation to flowers, fruit sets and rhizomes, whereas it increased biomass and biomass allocation to clonal ramet shoots. Within increasing water supply, biomass allocation to sexual reproduction decreased, whereas biomass allocation to clonal reproduction did not change. However, increasing water supply increased biomass allocation to ramet shoots but decreased that to ramet rhizomes. Therefore, increase in water supply inhibited sexual reproduction and thus changed the biomass allocation to clonal reproduction. Increasing nutrient supply increased fruit biomass and decreased biomass of shoots, leaves and rhizomes of clonal ramets, but did not affect biomass of other parts. With increasing nutrient supply, biomass allocation to fruits increased, whereas biomass allocation to leaves and shoots of clonal ramets decreased. Therefore, increase in nutrient supply enhanced sexual reproduction, but reduced clonal reproduction. We conclude that there is a trade-off between the sexual and clonal reproduction in H. laeve population in responses to water and nutrient supplies. The plastic responses of sexual and clonal reproduction of H. laeve populations to environmental factors may be an adaptation to heterogeneous environments.

Key words: Hedysarum laeve, sexual reproduction, clonal reproduction, nutrient, water, biomass allocation