Preliminary Study On Physiology And Ecology Of Germination Of Zostera Marina L. Seed

In the present study, we investigate the utilization and transformation of waterand storage nutrient rules in Z. marina seed germination, and compare seedmorphology, nutrient contents, germination and seedling survival and growth amongdifferent populations of eelgrass seeds, to identify the germination strategies ofdifferent populations. We also study the effects of different factors on the rapidgermination of eelgrass seeds to identify its dormancy type and find the key factorscontrolling eelgrass rapid germination, and for the first time investigate themechanism of low-salt promoting eelgrass germination. Eelgrass seeds are plantedusing burlap bags in natural sea areas and seed germination, seedling establishmentand growth are monitored, to invent a sowing method for eelgrass restoration. Thefindings of the research not only provide information and support for theestablishment of eelgrass seed physiology and ecology theory, but also technicalsupport for the use of seed in eelgrass restoration. The main results are summarized asfollows:1. To investigate the utilization and transformation of water and storage nutrientrules in the Z. marina seed germination, seed germination experiment was carried outin laboratory simulated the natural conditions (4℃). The results showed that under4℃and dark conditions, the accumulated germination rate was35%, and themean-time-to-germination (MTG) was86.16d. Water absorption of eelgrass seedduring germination can be divided into four stages, slow water absorption stage (0～30d), rapid water absorption stage (30～45d), inactive water absorption stage (45～75d) and second water absorption period (75d～). The main storage nutrients ofeelgrass seeds were starch, protein and lipid. In eelgrass seed germination, proteinwas firstly broken down to provide energy, followed by starch and lipid. Basic aminoacids and unsaturated fatty acids were preferentially used in the germination.2. Morphology and internal nutrient content of Z. marina seeds, as well as seed germination, seedling survival and growth and its physiological response, of threedifferent populations, including Swan Lake population, Lidao population andHuiquan population, were compared to find the suitable seed population to carry outlarge-scale seagrass bed restoration. The results showed that Huiquan populationseeds were the largest, significantly larger than the other two populations (P<0.05).The total sugar contents of different populations were significantly different fromeach other (P<0.05), and in descending order was Swan Lake> Lidao> Huiquan. Theprotein contents of Swan Lake and Huiquan populations were significantly higherthan Lidao population (P<0.05), however, the lipid contents of the three populationswere very low, only about1%. Germination capacity and young seedling viability ofthe three populations in descending order were Swan Lake> Lidao> Huiquan. It wasalso found that seed moisture and storage nutrient content were the key factorsaffecting seed germination and seedling survival of eelgrass. Low water content andnutrient-rich seeds had higher seed germination rate and seedling survival rate.3. A total of21treatments were set including acupuncturing seed coat, acid, drug,hormones and low-salt stimulation, cold stratification and poikilothermic treatment toexplore the effect of these different factors on the rapid germination of eelgrass seeds.The result showed physiological dormancy, physical dormancy and morphologicaldormancy exist in Z. marina, and low-salt treatment can contribute to rapidgermination of eelgrass seed and the optimal salinity is10. Different concentrations ofNaCl and PEG-6000(PEG) were used to simulate the different ion concentrations andosmotic pressure, combined with the changes of nutrients in the germination processof low-salt, to promote the mechanism of eelgrass seed germination. The resultsshowed that the mechanism of low-salt promoting rapid germination of eelgrass seedis to reduce the special ionic effect of NaCl, and to improve water absorption and thespeed of nutrient mobilization in the germination process.4. In October2010, eelgrass seed planting experiment was carried out in the SwanLake in Rongcheng City, using tile carpet sowing method (burlap bags) and seedgermination, seedling establishment and growth were monitored from March toSeptember2011. The result showed seed germination rate of the method was 38%~38.8%, seedling establishment rate was25.7%and seedling survival rate was7.42%. The monitoring results showed that, seedling exist after5months (March2011) and began to grow rapidly when water temperature rose to15℃in May.Creeping stem branch and flowering occurred in June and in August the plant grewrapidly, more and more fresh shoots existed and the lateral branch clustered. Theaverage lateral branch emergence rate was39.1%, and the average lateral shootemergence rate was16.7%. The plants of these burlap bags formed a seagrass patchwhich indicated the tile carpet sowing method is an effective seagrass seed sowingmethod.