Influence of the Repeated Flooding on Growth and Development of Acorus calamus Vegetation in Water-level-fluctuation Zone of the Three Gorges Reservoir

摘要

[Objective]The research aimed to study influence of the repeated flooding on growth and development of A. calamus in water-level-fluc-tuation zone of the Three Gorges Reservoir. [Method]A. calamus plants were exposed to water under the dark conditions respectively in September 2009 and September 2010. Then,they were taken away from the water,and grew in natural conditions in the following March and April respectively ( marked as S1,S2,S'1 and S'2) . The plant number was conducted statistics respectively. On May 7,the leaf number was made statistics. Length,width and rapid light responding curve of the leaf were determined. [Result]Repeated flooding restrained significantly plant germination under the dark condition. Plant number in S'1 and S'2 groups decreased by 38. 9% and 33. 3% respectively compared with the control. It also reduced survival rate of the plant. Plant number in S'2 group decreased by 16. 7% ( P <0. 05) compared with that of S2 group when they were taken away from the water. Both of flooding promoted elongation of the leaves,restrained leaves to grow wider,and also restrained leaf formation of the plants except for S1 and S'1 groups. Total leaf length of a plant decreased markedly after the second flooding which in S'1 and S'2 groups were 50. 6% and 36. 9% respectively less than that after the first flooding. Total leaf number of the plant in S'1and S'2 groups reduced significantly,and they were only 63. 1% and 38. 5% respectively of the control. Compared with the first flooding,total leaf length of a plant in the control increased signifi-cantly and decreased remarkably in S'2 group after the second flooding. Furthermore,light response ability of the relative electronic transfer rate ( rETR) in S'1 group wasn't significantly different from the control,and rETRmax in S'2 group was significantly less than the control. Moreover,non-photochemical quenching ( NPQ) decreased remarkably in S'1 and S'2 groups. It indicated that A. calamus had good restore ability of the light response,but restoring of its heat dissipation capacity was slower. [Conclusion]Repeated flooding inhibited plant growth and population recovery of A. calamus under the dark condition.