Study On The Relationship Between Seed Functional Traits And Germination In Songnen Grassland

Seed germination is the beginning of the life history for seed plants,which affects plant population continuation.Seed germination was not only affected by environmental factors,but also by seed functional traits.See traits reflects the original stable genetic information of plants and effects of environmental factors,therefore the effects of seed functional traits on germination has been widely attended by researchers.The previous study mainly focus on the effects of saline-alkaline stress,temperature and light on seed germination of plants in Songnen grassland.The information of the effects of seed functional traits on germination is lacked.In our study,we investigated the strategies of seed germination from morphological characters,dispersal model,dormancy type and seed reserves and reveals the seed reserve mobilization during germination for the grassland species.Our study determined seed traits(seed mass,seed volume,dispersal model,dormancy type,germination percentage)of 98 grassland species.Six species(Chloris virgata,Kochia scoparia,Lespedeza hedysaroides,Astragalus adsurgens,Leonurus artemisia and Dracocephalum moldavica)with different seed reserve type were selected to measure contents of starch,protein and fat in dry seeds and seed reserve(starch,fat,soluble sugar,soluble protein)mobilization during germination.The results showed that:1.The characteristics of seed functional traits: the change of seed mass and volume have 4-5 orders of magnitude for the 98 species in Songnen grassland.The seed mass of 55.1% species was less than 1 g.Small-seeded species mainly belonged to Asteraceae and Poaceae and large-seeded species mainly belonged to Fabaceae.The dormant type of most species was physiological dormancy and barochorous was the main dispersal model.The results illustrate that most species in Songnen grassland produce small seeds and the dispersal model and dormancy type of plants are suitable to their living environments.2.The relationship between seed functional traits and germination: the germination percentage of half of the species were more than 50%.Seed mass was negatively correlated with germination percentage(p < 0.05).Seed volume and dormancy type were not significantly correlated with germination percentage.Seed dispersal model was significantly correlated with germination.From our results,seed mass and dispersal model have more effects than other seed functional traits on germination.3.The relationship between seed reserves and germination: starch,protein and fat in dry seeds were not significantly correlated with germination percentage,but soluble sugar and protein contents were positively significantly correlated with germination rate for the six species.The higher soluble sugar and soluble protein content were,the faster germination rate for the different species in the same germination stage.The utilization of soluble protein,starch and fat is roughly same for the six species,Soluble protein contents is significantly reduced,Fat contents is no significant changes and starch contents showed a decreasing trend from imbibition to the early seedling stage.Our results for protein and fat utilization differ from those obtained for cultivated grasses and legumes during germination.The patterns of starch degradation and soluble sugar utilization from imbibition to the early seedling stage varied for species in the same family and with the same kind of life cycle.