Effects Of Livestock Ingestion On Seed Germination Of Plant Species In Grassland

To investigate the effects of livestock ingestion on the seed germination of plant speciesin the grassland, we conducted a series of laboratory experiments in which seeds of S.bungeana, S. Grandis, Roegneria varia, Cirsium segetum and Olgaea tangutica were treatedwith the rumen fluid and dung of dairy callte.Firstly, seeds of S. bungeana, S. Grandis and R. varia with different levels of dormancywere subjected to cold stratification (4℃) for10d,20d,30d and40d respectively to findout a best duration of cold stratification for each species to break down dormancy. Secondly,pretreated seeds of S. bungeana, S. Grandis and R. varia and seeds of C. segetum and O.tangutica were treated with rumen fluid to study how rumen fluid affect seed germinationpercentage and germination time and how different species response to rumen fluid.Treatments concluded original solution,1:1dilution,1:10dilution, boiled solution and thedistilled water (control group). Finally, seed germination experiment was carried out in dairycattle dung, in order to define the effects of dairy cattle dung on the seed germination andseedling growth.Results showed that4℃cold stratification could break dormancy of S. bungeana, S.Grandis and R. varia and enhance seeds germination. The optimal time of cold stratificationfor S. bungeana, S. Grandis and R. varia was20d,20d and10d respectively and thegermination percentage increased from (32.5±6.3)%,(36.7±7.3)%and (48.3±6.7)%in thecontrol group to (63.8±6.6)%,(78.3±3.3)%and (100±0)%in the optimal cold stratificationtreatments. Moreover, cold stratification reduced mean germination time of S. Grandis and R.varia, but exerted no significant effect on that of S. bungeana, which indicates that theirmechanisms of dormancy may be different.Rumen fluid suppressed seed germination of all5species. Germination percentage of S.bungeana, S. Grandis, R. varia, C. segetum and O. tangutica decreased significantly in thetreatment of undiluted rumen fluid. S. bungeana, S. Grandis and O. tangutica seeds weremore sensible to rumen fluid treatments. However rumen fluid treatments exerted weakernegative effects of R. varia and C. segetum seeds. Therefore, dairy cattle could be thepotential seed disperser. In addition, rumen fluid treatments prolonged mean germination time of O. tangutica from (17.9±1.2) d in control group to (32.9±1.9) d in the rumen fluid originalsolution treatment. However rumen fluid treatments did not exert significant effects ongermination time of S. bungeana, S. Grandis, R. varia and C. segetum seeds. The effects ofboiled rumen fluid on seeds germination were much weaker than that of original rumen fluid.All5species seed germination percentages in the boiled solution treatments weresignificantly greater than those in original solution treatments. Except for S. bungeana, allother4species’ germination percentages in the boiled solution treatment were notsignificantly different from those in the control treatments. Therefore, the major factor ofrumen fluid affecting seed germination is the large number of microorganisms and digestiveenzymes.S. bungeana, S. Grandis and O. tangutica seeds could not germinate in dairy cattle dungat all. Therefore dairy cattle might not be the effective seed disperser of these three species.On the contrary, a few R. varia and C. segetum seeds germinated in dung which did not exertnegative influence on their seedling growth at least in the early stage. As a result, dairy cattleis consider to be the seed disperser of both R. varia and C. segetum. The surface of cattle dunghardened because of dehydration, which leaded to the failure of seeds germinating from dung.