底质掩埋对苦草种子成苗和幼苗存活的影响

为探索底质掩埋对人工恢复苦草(Vallisneria natans)的影响,研究了塘泥和河沙掩埋0、1、3、5 cm深度下苦草种子的成苗状况和苦草幼苗的存活状况.结果表明,掩埋深度增加会显著降低种子的成苗率、幼苗的存活率、植株的株高和干重,其中掩埋深度达5 cm时,苦草种子不能成苗,幼苗不能存活,与无掩埋相比,掩埋1 cm和3 cm处理中,幼苗存活率的下降幅度显著低于种子成苗率,且掩埋1 cm处理的幼苗存活率下降不显著,掩埋3 cm处理的河沙组种子的成苗率和幼苗的存活率显著高于塘泥组;无掩埋、掩埋1 cm和掩埋3 cm处理中,塘泥组苦草的平均株高、株均干重和根冠比均显著大于河沙组.表明底质掩埋对苦草种子成苗的影响大于对幼苗存活的影响;塘泥比河沙更有利于苦草的生长,但掩埋深度较大时,塘泥对种子成苗率和幼苗存活率的影响比河沙更明显.

Effects of sediment burial on seed germination and seedling survival of Vallisneria natans

Sediment burial often happens in water bodies. This experiment investigated the effects of river sand burial and pond sediment burial on seed germination and seedling survival of Vallisneria natans at depth of 0, 1, 3 and 5 cm. The seed emergence rate, seedling survival rate, height and dry weight of seedlings decreased significantly with the increase of burial depth. No seed emergence was observed and no seedlings could survive when the burial depth was 5 cm. Compared with the control, seedling survival rates decreased less than seed emergence rates at burial depth of 1 cm and 3 cm, and no significant decrease was observed in seedling survival rates at burial depth of 1 cm. At burial depth of 3 cm, the seed emergence rate and seedling survival rate reduced more seriously by pond sediment than river sand. Average height, average dry weight and average root/shoot ratio were all apparently higher in pond sediment than river sand at burial depth of 0, 1 and 3 cm. This indicated that sediment burial had more negative effects on seed emergence than seedling survival, and pond sediment was more beneficial to the growth of V. natans than river sand, although it decreased seed emergence rate and seedling survival rate more significantly than river sand.