海南特有兰科植物华石斛的繁殖分配规律

华石斛为兰科石斛属多年生附生植物,在自然条件下结实率低,种子萌发条件苛刻。除了有性生殖,华石斛也可以克隆繁殖。笔者在海南省霸王岭设置5条样带,对样带内的华石斛进行种群监测,通过研究不同株龄华石斛个体的繁殖分配规律来为附生兰科植物的保育提供科学依据。结果表明,在华石斛整个生活史阶段,个体具备至少4根假鳞茎才能开始有性生殖,且对有性繁殖的投入逐年增大。华石斛的克隆生长则没有个体大小限制。根据繁殖器官生物量与植株总生物量的比例来看,随着华石斛个体株龄的增长,投入给繁殖活动的资源比例始终维持在27%左右,并且克隆繁殖始终占据2种繁殖方式的优势地位。

Reproductive Allocation of Dendrobium sinense,an Endemic Orchid Species to Hainan Island

Dendrobium sinense is a perennial epiphytic orchid,which belongs to the genus of Dendrobium and the family of Orchidaceae.Under nature conditions,D.sinense has a low seed setting rate and the environmental requirements for seed germination is very stringent.Besides sexual propagation,asexual ways like clonal propagation is also found in D.sinense.In this study,five transects were set up in Bawang Ridge of Hainan Province to monitor the dynamic change of D.sinense population and study the reproductive allocation rules of D.sinense plants at different age,in order to supply scientific evidence for the conservation of epiphytic orchids.The results showed that during the whole life history of D.sinense,individuals with at least four pseudobulbs could have sexual reproduction,and the investment paid into sexual reproduction increased year by year.Whereas,the clonal propagation of D.sinense was not limited by individual size.According to the ratio of reproductive organ biomass to total biomass,the proportion of resources devoted to reproductive activities was maintained at about 27％ through the whole life history.Clonal reproduction was found always being the dominant ones between the two reproduction methods.