The Comparative Study Of Fragment Regeneration Between Exotic And Native Aquatic Macrophytes

Fragment regeneration is one of the main reproduction way of aquatic macrophytes,in this paper,controlled experiments were conducted to study the effects of season,eutrophication and water depth on fragments.The experiment results are as follows:1.An experiment was conducted to analyze the effects of season and fragment lengths on fragment regeneration.The results showed that Ludwigia adscendena had more shoots and weaker rooting ability in summer,less shoots and stronger rooting ability in autumn;the regeneration ability and biomass of Hydrilla verticillata in summer were stronger than other species in autumn.Alternanthera philoxeroides had weak regeneration ability in both summer and autumn,but the RGR of fragments in summer were higher than those in autumn;Myriophyllum spicatum had more roots and biomass in autumn and Myriophyllum aquaticum also had stronger regeneration ability in autumn,but regeneration ability of Egeria densa had no difference between summer and autumn.The increasing lengths of fragments increased the regeneration ability of fragments,the reason might be that longer fragments supply more nutrition and growth hormone.The regeneration of exotic aquatic plants were weaker than those of native plants.2.Through the study on the effects of water nutrient and apex treatments on 5 aquatic plants,we found that fragments of L.adscendens with apex had no significant difference in root number and root length among nutrient levels,while it had more shoots in control treatments.Higher nutrient level significantly decreased the shoots of A.philoxeroides.Higher nutrient level promoted the rooting ability of M.aquaticum fragments and shooting ability of M.spicatum.Higher nutrient level inhibited the regeneration ability of M.aquaticum and M.spicatum.Nutrient level had no significant effects of the regeneration of H.verticillata.Apex significantly promoted the rooting abilty of L.adscendensand H.verticillata,while decreased their shooting ability and the length and node number of five species.Apex had no effects on A.philoxeroides and M.aquaticum.Apex had different effects on M.spicatum among nutrient level.3.The study effects of water depth and apex on regeneration ability of fragments showed that,lower water depth promoted the regeneration ability of fragments in part.The total shoot length of fragments with apex of M.aquaticum,the shoot number,total shoot length and RGR of fragments without apex of H.verticillata were all higher in 40cm-water-depth than in 50cm-water-depth,the same went for A.philoxeroides and M.spicatum,which had stronger regeneration ability and higher survival rate.Removing the apexes decreased the length and node number of fragments,inhibited the rooting ability and survival of L.adscendens and A.philoxeroides,but it promoted the shooting ability of L.adscendens,A.philoxeroides,M.spicatum and M.aquaticum,increased the amylum and TNC contents of L.adscendens,A.philoxeroides and M.spicatum.The regeneration ability,amylum and TNC contents of L.adscendens were all higher than those of A.philoxeroides;H.verticillata had higher rooting ability and RGR;the regeneration of M.spicatum were weaker than that of H.verticillata;most traits of M.spcatum were similar to those of M.aquaticum,but the RGR,amylum and TNC contents of M.spicatum were lower than those of M.aquaticum.