青藏高原东缘唇形科植物种子大小对萌发的影响研究

以青藏高原东缘地区24种唇形科(Lamiaceae)种子为材料,在室外自然光照条件下进行萌发试验,研究种子大小与萌发特性的关系,为当地的植被保护或恢复对策的制定提供一定的科学依据。结果表明:24种唇形科植物种子的百粒重为0.0061～0.5688 g,跨越2个数量级,平均大小0.1200 g,60%的物种种子百粒重小于0.1200 g,表明在青藏高原东缘唇形科植物种子中小种子占优势。种子大小与萌发率和萌发速率指数呈极显著负相关(P<0.01);种子大小与集中度呈极显著正相关(P<0.001);种子大小与萌发开始时间的相关性不显著。这些结果说明,这24种唇形科植物的大种子物种和小种子物种有2种相反的萌发对策:小种子萌发率高,萌发速率快,萌发历期短,萌发整齐性好;大种子与小种子相反,并共同与其扩散能力构成了一个由小种子物种(拓植能力)到大种子物种(竞争能力)的连续体,从种子萌发对策上解释了大、小种子物种在同一自然群落中如何共存的问题。

Effects of Seed Mass on Germination of Lamiaceae Species in the Eastern Qinghai-Tibetan Plateau

The effects of seed mass on germination characteristics of 24 Lamiaceae species in the eastern Tsinghai-Tibet were studied to provide selected scientific basis for protection and restoration of local vegetation.Seeds germinated under outdoors natural light.Seed weight of tested species were 0.0061～ 0.5688 g per hundred with the variation span of 102 and seed average weight is 0.1200 g.The seed weights of 60% tested species were less than 0.1200 g indicating dominant Lamiaceae species with small seeds in the eastern Tsinghai-Tibet.Germination percentage and germination rate were significantly negative related to seed mass(P<0.01).Seed mass and concentration degree showed significant positive relation(P<0.001).Seed mass and germination did not have significant correlation.There are two opposite germination strategies between large seeds and small seeds of these 24 Lamiaceae plants.Small seeds have higher germination percentage,faster germination rate and shorter duration of germination.Large seeds and small seeds constitute a continuum with their dispersal ability from small-seeded species(colonization) to large-seeded species(competition).This strategy of seed germination can explain how the large and small seeds plants coexist in the same natural community.