Chin J Plant Ecol ›› 2010, Vol. 34 ›› Issue (12): 1404-1413.DOI: 10.3773/j.issn.1005-264x.2010.12.006

• Research Articles • Previous Articles     Next Articles

Effects of simulated submergence on seed germination of four common annual herbs in the Three Gorges Reservoir Region, China

WANG Xin1,2, GAO Xian-Ming1,*()   

  1. 1State Key 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
  • Received:2010-02-24 Accepted:2010-05-31 Online:2010-02-24 Published:2010-12-28
  • Contact: GAO Xian-Ming


Aims Flooding disturbance can change the species composition of plant communities. Field investigation showed that annual herbs were an important part of the natural vegetation of the water-level-fluctuating zone (WLFZ) in the Three Gorges Reservoir, but there are few studies on the effects of flooding on annual plants. Annual, which reproduce from seeds, usually grow fast and can rapidly rehabilitate areas. Our objective is to determine the effects of water submergence on the germination of seeds of annuals, with regard to possible use of annual plants in vegetation restoration of WLFZ in the Three Gorges area.
Methods Seeds of four annuals, Echinochloa crusgali, Setaria pumila, Digitaria sanguinalis and Arthraxon hispidus, were collected in autumn 2008 in Wushan County of Chongqing Municipality. Seeds for control (CK) were kept in envelopes; seeds for water submergence treatments were buried in soil in plastic containers and water was poured into the containers to maintain a water layer on the soil surface. We used six different durations of water submergence, 30, 75, 115, 155, 195 and 240 days, to match water level operation of the Three Gorges Reservoir. After treatments ended, seeds were separated from soil by water flushing and filtering with gauze. The treated seeds were incubated in pots filled with soil watered daily. Three replicates of 50 seeds per sample were used for each treatment. Germinated seeds were counted daily until the end of germination.
Important findings Water submergence significantly affected seed germination rate and germination course of all four annuals. Germination rates first increased and then decreased with increased duration of submergence. Germination rates with short-time submergence treatments were significantly higher than CK. Submergence can break seed dormancy and increase the rate of seed germination. Submergence also accelerated the course of germination. Short-time submergence treatments increased germination indices significantly greater than in CK, and the germination periods were shorter, but long-time submergence had little effect on the course of seed germination. Overall, the germination rates of all treatments of all annuals were > 40%. Therefore, these four annuals are useful in vegetation restoration of WLFZ in the Three Gorges Reservoir.

Key words: annual herbs, revegetation, seed germination, submergence