The Study On Seed Germination Characteristics Of 43 Caryophyllales Species From The Eastern Qinghai-Tibet Plateau

Seed germination is one of the most important period in plant life history. Seedlings establishment, species reproduction and the maintenance and stability of community structure are starting to seed germination stage. Therefore, there is a profound ecological meaning in further investigating seed germination characteristics. However, the current studies are focused on seed germination-related within the same species, between different individuals in the same population and between different populations and studies are mostly conducted in tropical and temperate herbaceous or woody while the researches on germination in Qinghai-Tibet Plateau which is under a special region is rare. Therefore, we aim the 43 Caryophyllales species (belonging to Polygonaceae, Chenopodiaceae and Caryophyllaceae) as the research objects and consider the effect of the light, differences of families and genera and seed size on characteristics of seed germination as to provide some ecological bases for communities' construction in the eastern Qinghai-Tibet Plateau. Our results show that:(1) The germination percentage of 43 Caryophyllales species from the eastern Qinghai-Tibet Plateau are tested head skewed distribution. The number of low germination percentage (less than 20%) is more than 50% in all of these species.(2) The change in light intensity significantly affects only the mean germination time(MGT) of 43 Caryophyllales species while has no significant effect on the germination percentage(GP), germination index(GI) and day to first germination(DFG) and with the light intensity increasing, the MGT delays. In family classification levels, the light has no significant effect on the GP, GI, MGT and DFG of Polygonaceae and Chenopodiaceae plants. Light has no significant effect on GP. GI and DFG of Caryophyllaceae but there is a significant effect on the MGT. With light intensity increasing, the MGT of Polygonaceae and Caryophyllaceae delays(3) The difference among families below the Caryophyllales has no significant effect on GP and GI but has significant effect on MGT and DFG. The difference among genera below the Polygonaceae has significant effect on GP, GI and MGT but doesn't affect DFG. The difference among genera below the Chenopodiaceae has no effect on the GI but has significant effect on the GI. MGT and DFG. The difference among genera below the Caryophyllaceae has significant effect on GP and GI but there is no effect on MGT and DFG.(4) All of the GP, GI, MGT and DFG are no significant relation to seed size in 43 Caryophyllales species. Under family classification levels, all of the GP, GI, MGT and DFG show no significant relation to seed size in Polygonaceae. Both in Chenopodiaceae and Caryophyllaceae, GP and GI have significantly positive correlation to seed size while MGT and DFG have significantly negative correlation to seed size, that is, with the increasing in seed size, both GP and GI are also higher while the MGT and DFG advance.(5) There is a significantly negative relationship between relative light germination(RLG) and seed size in 43 Caryophyllales species, that means germination become less dependent on light with increasing in seed size. Both in Polygonaceae and Chenopodiaceae, there is a no significant relationship between RLG and seed size, but the trends are negative while there is also a significantly negative relationship between RLG and seed size in Caryophyllaceae.