Abstract: The effects of water quality and substrate type on the seed germination of Vallisneria spiralis L. were investigated, with the goal to explore its strategies of seed germination under eutrophic water condition. The results showed that the seed germination percentage of V. spiralis was 40%-69% under natural temperature and light conditions. Water bodies had little effect on the seed germination of V. spiralis. However, compared to the other two waters, the cumulative germination percentage and total germination percentage were relatively higher, the germination rate was faster and the mean germination time was shorter in the water of Taihu. Substrate types significantly affected the seed germination of V. spiralis, which was the best in the loess and the worst in the sand. In the substrate of loess, the total germination percentage was 20% higher, the germination rate doubled, and the mean germination time was 11 days shorter than those in the sand. The seed germination percentage in the water (64%) was greatly higher than in the sediment (50%), while the seed germination efficiency was significantly lower in the water than in the sediment (germination rate 5% lower and mean germination time 11 days longer). This study provides a theoretical basis for vegetation restoration in eutrophic lakes using the V. spiralis seeds.

Key words: dry farming regions, dual-mulching of ridges and furrows.