紫花地丁二型性种子的萌发特性及其生态意义

Germination characteristics and ecological significance of dimorphic seeds of Viola philippica

紫花地丁(Viola philippica)具有开放花(CH)和闭锁花(CL)形成的二型性种子。在对紫花地丁CH种子和CL种子形态观测的基础上,比较了这两种类型种子在不同温度、光照以及贮藏时间下的萌发特性。结果表明,1)CH种子长、宽以及千粒重显著大于CL种子(P<0.05)。2)CH种子和CL种子最适萌发温度均为20℃,萌发率均在95%以上,在10℃条件下均不萌发,但在高温(30℃)条件下CL种子的萌发率显著高于CH种子(P<0.05),其它温度下,两者萌发率均无显著差异(P>0.05)。3)CH种子对光照条件敏感,黑暗条件对其萌发具有极显著的抑制作用(P<0.01),而CL种子在12h光照和全黑暗条件下萌发差异不显著(P>0.05)。4)CH种子贮藏210d后,萌发率显著降低(P<0.05),而CL种子则在贮藏510d后萌发率才显著下降(P<0.05)。CH种子于春季成熟后即可迅速萌发,CL种子一部分于之后的季节萌发,另一部分成为短暂土壤种子库于次年春季萌发。紫花地丁通过二型性种子更好地适应时空异质性环境,提高了其适合度。

Viola philippica has dimorphic seeds which come from chasmogamous flowers and cleistogamous flowers.Based on the morphology observation of CH and CL seed,we compared the germination characteristics of the two types of seeds at different temperatures,light conditions and the storage time.The results showed that：1）The length,width and weight of CL seeds were significantly lighter（P〈0.05）than CH seeds.2）The optimum germination temperatures of CH and CL seeds were 20℃,and both the germination rates were above 95%.Both of the two types of seeds did not germinate at a low temperature（10℃）,but germination rate of CH seeds was significantly lower（P〈0.05）than CL seeds at a high temperature（30℃）.As to the moderate temperature（15-25℃）,the germination rates of CH and CL seeds did not differ significant（P〉0.05）.3）CH seeds were sensitive to light and its germination rate would be inhibited in the dark（P〈0.01）,but the germination rate of CL seeds had no significantly difference at 12 hlight and full dark conditions（P〉0.05）.4）Compared with the control,the germination rates of CH and CL seeds significantly decreased after 210dand510dstorage（P〈0.05）,respectively.CH seeds maturing in the spring can quickly germinate.CL seeds germinated later in the season than CH seeds.The part of CL seeds could germinate,another part became transient soil seed bank and could germinate next spring.The differences in germination characteristics between dimorphic seeds of V.philippicaimproved the species＇ fitness to heterogeneous habitats.