The effect of water-level fluctuations on seedling recruitment in an aquatic macrophyte Nymphoides indica (L.) Kuntze (Menyanthaceae)

We examined seed bank characteristics and seed germination and the survival of seedlings to understand the significance of water-level fluctuations on sexual regeneration in Nymphoides indica (L.) Kuntze. The seed bank existed throughout the pond. The longevity of the seed bank was more than 3 years. Seed germination started on the exposed mudflat as soon as water drawdown occurred. At the juvenile stage, exposed conditions were required for seedling growth and the young seedlings died under submergence. It was suggested that seedling establishment was successful after occasional water drawdown or along the water margin according to the period and pattern of water-level fluctuation. This study indicated the significance of the exposed mudflat at the water edge for seed germination and the growth of juvenile plants to the success of sexual regeneration in N. indica.