Preliminary Study on Clustering Effect on Seed Germination for Several Aquatic Plants

This article investigated the clustering effect on seed germination for 10 aquatic plants.Results showed that the response of seed germination to seedclustering in Hydrocharitaceae was mostly positive,with the seed germination rates of Ottelia acuminata,O.emersa,Vallisneria denseserrulata,Hydrocharis dubia,and Blyxa aubertii significantly improved.The germination rates of V.natans and V.spinulosa were significantly promoted when seeds clustered.Conversely,the seed germination rate of Myriophyllum spicatum was significantly inhibited and no significant difference was found in Potamogeton perfoliatus,Triglochin palustre when seeds were clustered.The clustering effect on seed germination may be related to their reproductive strategy.Of these species,population expansion of Hydrocharitaceae mainly depends on seeds or sexual reproduction accounting a larger proportion in the reproduction allocation.Their seeds are often clustered because of the gelatinous matter in the fruit.When these seeds meet suitable conditions,they produce a patch area of single species and occupy the habitat rapidly.Contrarily,for M.spicatum,P.perfoliatus and T.palustre,whose expansion mainly depends on clonal propagation,the response of seed germination to seedclustering showed a negative or no significant effect.