Abstract: By the method of microscopic examination, the soil seed bank structure and diversity of two natural wetlands (Shibasuo Lake and Shengjin Lake) and their corresponding reclaimed paddy fields at the lower reaches of Yangtze River in Anhui, China were investigated. The total seed storage in topsoil (0-10 cm) was 83 499-109 141 ind·m^-2 for natural wetlands and 9140–47452 ind·m^-2 for reclaimed paddy fields. In natural wetlands, the seeds were of 16-30 grass plant species, being dominant with Polygonaceae and Cyperaceae or yperaceae and Gramineae; while in reclaimed paddy fields, the seeds were of 7-16 grass plant species, with the dominant of Gramineae. The seed storage and species numbers were greater in Shengjin Lake than in Shibasuo Lake. Higher seed bank storage and more species were observed in the paddy fields from Shibasuo wetland with 30 years of cultivation than from the Shengjin Lake wetland with over 50 years of cultivation. The shift of paddy fields from natural wetlands reduced the seed bank storage and the seed species number markedly, indicating that biodiversity was strongly disturbed when the ecosystem was managed by human. Therefore, conservation of natural wetlands is of significance in sustaining the biodiversity and ecofunction of Yangtze River basin.

Key words: Oryza sativa, Allelopathic potential, Bioassay method, Application