A study on seed germination characteristics of 15 Chenopodiaceae and Polygonaceae species of the eastern edge of QinghaiTibet Plateau

Under different light gradients 100% and 3% natural sunlight (NS), both seed germination percentage (GP) and relative light germination rate (RLG) of 15 Chenopodiaceae and Polygonaceae species of the eastern edge of QinghaiTibet Plateau were measured in this study. Differences on germination of these species under two light levels were also analyzed by pairedsamples T test. The relationship between seed size and RLG was investigated by Pearson analysis. The T test displayed that germination response to lights was different in all of the species, while the Pearson analysis showed that germination became less dependent on lights with increasing seed mass. We also found that there were differences on germination bewteen annual and perennial species. The germination of annual species needed light, but became less dependent with increasing seed mass (P0.001); while the germination of perennial species did not depend on the lights (P0.05). The study demonstrated that germination responses to lights of the 15 Chenopodiaceae and Polygonaceae species were affected by both seed size and life form.