淀山湖3种沉水植物的种子萌发生态

Seed germination ecology of three submerged macropbytes in Dianshan Lake.

探讨淀山湖３种主要沉水植物（殖草、大茨藻和苦草）种子萌发与种皮、水温以及萌发基质之间的关系．种皮对种子萌发的限制作用程度与种皮结构有关，种皮破裂后，发芽率和萌发速率均增高．水温对种子前发具有一定的促进作用，发芽率均以２０℃时最大，但萌发速率却为２８℃＞２０℃＞１０℃．不同沉水植物种子萌发的最适基质不同，苦草和菹草为水加土，而大茨藻则为土；单纯水中的发芽率和萌发速率均最低．

In this paper, the. relationship between the germination of 3 submerged macrophytes inDianshan Lake and their seed coat, water temperature and substrate is studied under controlled condition. The results show that seed germination is controlled by the structure ofseed coat. When the seed coat is cracked, the germination rate and its speed are increased. Water temperature also plays an important role in promoting germination. Maximum germination can be occured at 20℃, but the speed of germination is increased withincreasing temperature. The optimum substrate for germination of Vallisneria spiralis andPotamogeton crispus is water plus soil, and that for Najas marina is soil. In water, thegermination rate and its speed are the lowest.