Influence of water logging time on the growth of Kandelia candel seedlings

摘要

Influence of waterlogging time on the growth of Kandelia candel (L.) Druce seedlings grown for 70 d in the artificial-tidal tanks' simulated semidiurnal tide under greenhouse is studied. Sand and soil act as the substrate and artificial sea-water with salinity of 15 is used in cultivation. Shorter waterlogging time (inundated for about 2～4 h) promotes the growth of K. candel seedlings, while longer time (inundated more than 8 h) or no waterlogging (0 h) inhibits their growth. The number and length of aerating roots increase with the increase of waterlogging time. Under existing conditions, the optimal waterlogging time for the growth of K. candel seedlings is about 2～4 h in every tide cycle. Compared with other treatments, the 2 h sanded treatments obtain the highest biomass of seedlings, have the lowest mass loss of hypocotyl and broaden the photosynthetic area by increasing the area per leaf after 70-d cultivation. And the soil treatments have the similar tendency. However, waterlogging for 8 h in every tide cycle is critical for normal development of seedlings. K. candel seedlings are highly tolerant to waterlogging and a proper waterlogging is beneficial to the growth of K. candel seedlings.