土壤基质和水分对珙桐幼苗生长的影响

Effects of Soil Matrix and Moisture on the Growth of Davidia involucrata Seedlings

珙桐是我国的一级濒危保护植物,探讨其迁地保护的生态限制因子尤为重要。以2年生珙桐为研究对象,采用盆栽试验在3种土壤基质下,设置3种水分梯度,分别为田间持水量的80%~90%、60%~70%以及40%~50%。研究珙桐幼苗株高、地径、根系和叶片氮、磷含量对土壤水分的响应,以及在不同土壤水分下珙桐幼苗的生物量分配特征。结果表明,不同水分处理对珙桐幼苗的株高、地径均有影响,干旱处理后期珙桐幼苗的株高及地径增量显著下降;水分胁迫降低了叶片的生物量,增加了根系的生物量和根冠比;随水分含量减少,叶片及根系氮含量呈上升趋势;土壤基质对幼苗的株高、地径增量及净光合速率的影响差异不显著。说明珙桐幼苗对干旱胁迫较为敏感,且耐旱能力较差,土壤基质的适应范围较广。

Davidia involucratais a rare and endangered plant species and has been listed as the first degree national protective plant.It is significant to find out the ecological limiting factors for the off-site preservation of D.involucrata.A pot experiment method was used to study the effects of soil moisture and soil matrix on 2-year-old D.involucrataseedlings.The results suggested that,the plant height and ground diameter dropped significantly at the end of drought processing.Water stress decreased the leaf biomass,and increased the root biomass and root cap ratio.Leaf nitrogen and root nitrogen contents presented a modest increase trend with the decrease of soil water.The effects of soil matrix on the the seedling height and Pnwas not significant.The results above mentioned indicated that D.involucrata seedlings was sensitive to drought stress,its drought resistance was relatively poor,and seedlings had a wide adaptation range of soil matrixes.