Seed Germination Strategy Of 31 Common Weeds On The Eastern Qinghai-Tibet Plateau

As the initial stage of plant life history cycle, seed germination plays a vital role in seedling establishment, individual development and the maintenance and stability of community structure. Thus, whether in plant ecology or plant evolutionary biology, the research about seed germination-related field is of great theoretical significance and practical value. But the current research on seed germination has a lot of limitations. The limitations come from both research materials such as species' constraints and experimental design and so on. Therefore, we aim 31 common weed species (belonging to Boraginaceae, Compositae and Poaceae) as the research objects and consider the effect of the light, habitat. altitude and life form on characteristics of seed germination as to reveal the common weeds' germination patterns and laws. We hope that our research can provide some theoretical bases for communities' construction of the eastern Qinghai-Tibet Plateau and poisonous weeds' prevention. Our results show that:1. The germination patterns of 31 species used in this study can be divided into four types: rapid, intermediate, slow and low germination. Intermediate and slow germination have a high percentage in these species (both 32.3%), rapid germination has a percentage of 25.8 while low germination only has a percentage of 9.7.2. On the whole, light intensity has no significant effect on germination percentage(GP). germination index(GI) and day to first germination(DFG) but has a significant effect on germination period. With the light intensity increases. the germination period prolongs. In Mesad, light intensity has no significant effect on GP, GI. DFG and germination period but with the light intensity increases. GP increases; In Siccocolous. light intensity has no significant effect on GP, GI, DFG and germination period but with the light intensity increases. the germination period prolongs. In family levels. light intensity has no significant effect on GP. GI, DFG and germination period in Boraginaceae. Compositae and Poaceae species.3. The habitat has a certain influence on germination ability. Overall. Siccocolous have a higher GP and GI than Mesad and Siccocolous have a quicker DFG. For the Boraginaceae, Siccocolous have a higher GP. a quicker GI, a earlier DFG and longer germination period than Mesad. For the Compositae. Siccocolous have a higher GP. a quicker GI. a earlier DFG and shorter germination period than Mesad. For the Poaceae, Siccocolous have a higher GP, a quicker GI, a earlier DFG and longer germination period than Mesad.4. Overall, both GP and GI have no significant relation to altitude but there is a significantly negative relationship between DFG and altitude and also between germination period and altitude. That is, with increasing in altitude, DFG advances and germination period becomes short. In Mesad, GP, GI and germination period have no significant relation to altitude but there is a significantly negative relationship between DFG and altitude. That is, with increasing in altitude, DFG advances. In Siccocolous, GP, GI and germination period have no significant relation to altitude but there is a significantly negative relationship between DFG and altitude. That is, with increasing in altitude, DFG advances. All of the GP, GI, DFG and germination period have no significant relation to altitude in Boraginaceae, Compositae and Poaceae species.5. There are some differences in germination ability between different life forms. In Boraginaceae, there is no significant difference about germination characteristics in two life forms but the perennial GP is still higher than the annual GP. In Compositae, DFG of perennial is significantly later than DFG of annual. There is no significant difference about GP in two life forms but the annual GP is still higher than the perennial GP. In Poaceae, germination period of perennial is significantly longer than germination period of annual and the perennial GP is significantly higher than the annual GP.