Ecological Responses Of Germination Of Scirpus Mariqueter Seeds From Different Populations And The Subsequent Clonal Growth To Salinity And Temperature

The plants living in the salt marsh in the coastal wetlands of the Yangtze River estuary play an important ecological role in regulating climate,purifying water quality,providing habitat,maintaining coastline stability and protecting biodiversity.Scirpus mariqueter,as a typical pioneer plant in the coastal wetlands of the Yangtze River Estuary,has important and unique ecological value.For S.mariqueter,environmental factors,especially the temperature and soil salinity of the habitat,directly affect its seed germination and clonal growth.Soil salinity is one of the important environmental factors that restrict plant growth in the coastal wetlands,and it has an important impact on the survival,growth and distribution of the plants in the salt marsh.The study on the different damages to plants caused by low temperature environment and the physiological mechanism of cold resistance produced by plants in response and adaptation to the low temperature environment can provide important references for plant in terms of cold resistance exercise,breeding and ecological restoration.Therefore,a systematic study on the responses of the germination of S.mariqueter seeds from different populations and the subsequent clonal growth to salinity,temperature and their interactions would have very important ecological significance and practical value,which could provide technical support for conservation and restoration of S.mariqueter population.In this study,we selected S.mariqueter seeds from different populations,and through a series of laboratory experiments,explored the effects of temperature,salinity and duration at seed storage,soil salinity at germination,as well as their interactions on the germination of S.mariqueter seeds from different populations and the subsequent clonal growth.The main conclusions of the research were as follows:1)The order of germination ability of S.mariqueter seeds from the two populations and subsequent clonal growth ability was: population inside the embankment > population outside the embankment.The S.mariqueter seeds from the different populations had different tolerance to the salinities at seed storage.During the seed storage at low temperature,the salinities at seed storage inhibited the seed vigor of the population inside the embankment,but 12 ‰ seed storage salinity promoted the seed vigor of the population outside the embankment.Soil salinities at the seed germination inhibited the germination of S.mariqueter seeds.The seeds from the population outside the embankment could withstand a slight salt stress,and the relative salt tolerance of the seeds from the population outside the embankment was stronger than the seeds from the population inside the embankment when the soil salinity at germination was higher.2)The optimal storage temperature and time of S.mariqueter seeds from different populations were different.The seeds from the population inside the embankment had the highest vigor when the temperature of seed storage was 0?;the seeds from the population outside the embankment had the highest vigor when the temperature of seed storage was-5 ?;the optimal storage time for the seeds from the population inside the embankment was 4 months or more,and that of seeds from the population outside the embankment was 3 months.3)Salinities at seed storage and germination had a significant interaction effect on the germination of S.mariqueter seeds from the populations inside and outside the embankment.With increase of the salinity at germination,when the temperature at seed storage was-5 ?,when the salinity reached high,the seed vigor of the population inside the embankment decreased significantly,whereas,the seed vigor of the population outside the embankment increased at first and then decreased;when the temperature at seed storage was 0?,the seed vigor of the population inside the embankment did not change significantly,and the seed vigor of the population outside the embankment decreased significantly,when the salinity reached high;when the temperature at seed storage was 5 ?,the seed vigor of the population inside the embankment decreased significantly,and the seed vigor of the population outside the embankment significantly reduced when the salinity reached high.4)Salinities at seed storage and germination generally inhibited the growth of new populations produced from the S.mariqueter seeds from the populations inside and outside the embankment.With the increase of soil salinity,ramet height,leaf area and biomass decreased.However,when the temperature at seed storage was high,a slight salinity at seed storage could increase the leaf area of the new populations generated from the seeds from the populations inside and outside the embankment.In the treatment with lower storage temperature,a slight salinity at germination could promote the increase of ramet height.5)Salinities at seed storage and germination generally inhibited the clonal propagation of new populations generated from S.mariqueter seeds from the populations inside and outside the embankment.With the increase of soil salinity,the ramet number,ramet height,rhizome length and bulb number of S.mariqueter clone decreased.6)Salinities at seed storage and germination changed the ways of the new populations of S.mariqueter generated by the seeds from population inside the embankment responding to the change of seed storage temperature.At low salinity,with the decrease of seed storage temperature,the vegetative growth,clonal reproduction and biomass of new populations produced from seeds reduced,and the distribution center of biomass shifted to the underground part;at high salinity,with the decrease of seed storage temperature,the vegetative growth,clonal reproduction and biomass of new populations generated from seeds reduced,and the distribution center of biomass shifted to the underground part at first and then to the above-ground part.