濒危植物海南龙血树种子萌发及其环境适应性分析

Seed Germination and Its Environment Adaptability of Endangered Tree Dracaena cambodiana

摘要:

为了解海南龙血树(Dracaena cambodiana)濒危的机制,研究了果皮、温度、水分和光照强度等对其种子萌发的影响,并分析海南龙血树种子萌发的环境适应性。结果表明,果皮对海南龙血树种子萌发有显著抑制作用,去除果皮且用果皮浸泡液浇灌可以显著促进种子的萌发。种子萌发对温度极为敏感,25℃是种子萌发适宜的温度,低于15℃或高于30℃均不能萌发,变温处理对种子萌发具有一定的促进作用。海南龙血树种子萌发需要较高的遮荫度,光照强度对种子萌发有显著影响。种子萌发对基质的水分含量不敏感,在含水量为9.09%~20.00%的河沙基质中,种子的萌发率、萌发速率指数、萌发时滞和萌发指数均无显著差异。因此,海南龙血树种子萌发对果皮、温度、光照强度等微环境的依赖性较强,原有生境破坏导致种子萌发微环境改变可能是海南龙血树居群有性生殖失败,海南龙血树处于濒危状态的主要原因之一。

Abstract:

In order to reveal the endangered mechanisms of Dracaena cambodiana, the effects of pericarp, temperature, soil moisture and light intensity on seed germination of D. cambodiana were studied, and its environment adaptability was analyzed. The results showed that seed germination of D. cambodiana was significantly inhibited by pericarp, and could be significantly promoted by removing pericarp and watering pericarp soak solution. Seed germination was very sensitive to temperature with suitable temperature of 25℃, and seeds could not germinate under below 15℃ or above 30℃. Alternating-temperature had certain facilitation to seed germination. The germination of D. cambodiana seeds need high shading density, light intensity had significant effect on seed germination. The germination of D. cambodiana seeds was insensitive to soil moisture, there were not significant differences on GP (germination rate), CRG (coefficient of germination rate), GTL (germination time lag) and GI (germination index) among soil moistures ranged from 9.09% to 20.00%. Therefore, the germination of D. cambodiana seeds strongly depended on pericarp and microenvironment factors, i.e. temperature and light intensity. The microenvironment changes caused by habitat destruction might be one of main reasons for failure of sexual reproduction and endangerment of D. cambodiana.