不同温度和水分胁迫对高寒草地毒杂草黄帚橐吾种子发芽的影响

Effects of Temperature and Water Stress on Germination of Ligularia virgaurea seed in Alpine Grassland

黄帚橐吾是高寒草甸分布广泛的毒杂草,研究黄帚橐吾种子发芽和幼苗生长的适宜条件对探索黄帚橐吾在青藏高原的扩散机制具有重要意义。本研究通过设置不同的温度和水分梯度,比较黄帚橐吾种子在不同条件下的发芽情况与幼苗的生长状况,以探讨黄帚橐吾种子和幼苗对温度和水分胁迫的耐受能力。主要研究结果如下:黄帚橐吾种子在30℃条件下发芽率和发芽指数最高,在15℃、20℃和25℃时仍维持相对较高的发芽率和发芽指数;胚根长在20℃时具有最高值,胚芽长则在25℃时具有最高值。随着渗透势的降低,黄帚橐吾的发芽率、发芽指数、胚根长和胚芽长均逐渐降低,其中在-0.3MPa条件下,黄帚橐吾的发芽率和胚根长与对照(0MPa)相比差异不显著,在-1.2MPa条件下,黄帚橐吾的发芽率、发芽指数、胚根长和胚芽长相比-0.9MPa而言均有少量的回升。综上所述,黄帚橐吾的种子发芽和幼苗生长可以耐受较大的温度变化范围(15℃~30℃)以及一定程度的干旱胁迫,这为其种群的维持和更新提供了保证,也部分解释了黄帚橐吾在青藏高原得到快速扩散的原因。

Ligularia virgaurea is toxic weed spread widely in alpine grassland.The study of appropriate conditions of L.virgaurea seed germination and seedling growth is useful for the exploration of mechanism of L.virgaurea spread in the Qinghai-Tibetan Plateau.This study compared the seed germination and seedling growth of L.virgaurea under different temperature and osmotic potential.It was to explore the tolerance ability of L.virgaurea to temperature and water stresses.The mainly results as follows:the highest germination rate and germination index of L.virgaurea seed appeared under 30℃condition,they were also higher under 15℃、20℃and 25℃relatively.It was highest under 20℃for root length and 25℃for shoot length.The germination rate,germination index,root length and shoot length decreased gradually with the decrease of osmotic potential.It was not significantly different under-0.3 MPa compared to control(0 MPa)in germination rate and root length.There was a little rise under-1.2 MPa compared to-0.9 MPa in germination rate,germination index,root length and shoot length.Therefore,the seed germination and seedling growth of L.virgaurea could tolerate in a range of temperature and osmotic potential stress.This may provide guarantee for maintaining and regeneration of L.virgaurea population,and partly explain the fast spread of L.virgaurea in the Qinghai-Tibetan Plateau.