Chin J Plant Ecol ›› 2011, Vol. 35 ›› Issue (3): 237-246.DOI: 10.3724/SP.J.1258.2011.00237

• Research Articles •     Next Articles

Seed submergence tolerance of four annual species growing in the water-level-fluctuation zone of Three Gorges Reservoir, China, and effects of long-term submergence on their seed germination

SHEN Jian-Hong, ZENG Bo*(), LEI Shu-Tong, SU Xiao-Lei, HUANG Wen-Jun   

  1. Key Laboratory of Eco-environment in Three Gorges Reservoir Region of Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in Three Gorges Reservoir Region, School of Life Science, Southwest University, Chongqing 400715, China
  • Received:2010-02-09 Accepted:2011-01-04 Online:2011-02-09 Published:2011-03-02
  • Contact: ZENG Bo

Abstract:

Aims Our objective was to examine seeds of Echinochloa crusgalli, Xanthium sibiricum, Aeschynomene indica and Polygonum hydropiper, four common annual species growing in the water-level-fluctuation zone of Three Gorges Reservoir in China, in regard to tolerance of submergence and germination in the changing environment of the zone.
Methods We divided the water-level-fluctuation zone into nine elevational zones according to the Wusong Elevation criterion. We then observed seed submergence tolerance and the effects of submergence on seed germination in a “water impoundment-water recession” cycle after seeds of the four species were sown in the nine elevational zones. Seed germination was divided into seeds with and without sand sediment on surface.
Important findings Ripe seeds (or fruits) of the four species kept their vitality after submergence. The starting time for seed germination after the end of submergence and seed germination duration both gradually decreased with decreasing elevation (p < 0.01), and the starting time for seed germination was significantly reduced below 169 m (p < 0.01). Overall, within the same elevational zone, the starting time for seed germination after the end of submergence was longest for A. indica, followed by X. sibiricum, and shortest for P. hydropiper. For E. crusgalli, X. sibiricum and P. hydropiper, seed germination percentage first increased and then decreased with decreasing elevation, while it decreased for A. indica. Sand sedimentation had little effect on seed germination; the effect was positive for X. sibiricum and negative for A. indica. We concluded that seeds (or fruits) of the four annuals can tolerate submergence and germinate successfully in the changing environment of water-level-fluctuation zone. Therefore, these species are useful in the revegetation and restoration of this zone of the Three Gorges Reservoir.

Key words: Aeschynomene indica, Echinochloa crusgalli, Polygonum hydropiper, revegetation, seed germination, submergence, tolerance, Xanthium sibiricum