低温预处理对不同储存时间黄帚橐吾种子发芽的影响

Effect of different low temperature pretreatment time on seed germination of Ligularia virgaurea

黄帚橐吾是分布在高寒草甸的一种常见毒害草,研究黄帚橐吾种子萌发的影响因素,对于探索黄帚橐吾在高寒草地上的扩散机制以及有效防除黄帚橐吾具有重要意义。通过对不同年份采集的黄帚橐吾种子进行不同的低温预处理,比较其发芽率、发芽指数、根长和苗长等的变化,探讨低温预处理对黄帚橐吾种子萌发和幼苗生长的影响。结果表明:经过4℃预处理24 h和-20℃预处理2 h,当年采集的黄帚橐吾种子发芽率有明显提高;经过-20℃预处理2 h,黄帚橐吾种子发芽指数无明显变化,4℃处理24 h后发芽指数也无明显变化,但经过48、72 h的4℃低温预处理后,发芽指数显著低于对照;随着4℃处理时间的延长,黄帚橐吾根长和苗长均有降低的趋势,而经过短时间(0.5 h)的-20℃预处理,储存1年后的黄帚橐吾种子苗长显著高于对照,根长无显著变化。综上所述,储存1年的黄帚橐吾种子的萌发活力低于当年采集的种子,但经过低温预处理后二者在发芽指数和苗长上的差距有所减小。因此,低温处理可以改善黄帚橐吾种子经过长期储存而引起的萌发活力降低的现象,但长时间低温处理会对黄帚橐吾幼苗的生长产生一定的抑制。

Ligularia virgaurea is a common poisonous weed distributed in alpine meadow.The study of factors affecting the seed germination of L.virgaurea is of great significance to explore the spread mechanism and efficient control of L.virgaurea in alpine plateau.In this study, the seeds of L.virgaurea collected in different years were pretreated at low temperatures to compare the germination rate, germination index, root length and seedling length of L.virgaurea,so as to explore the effect of low temperature pretreatment on the seed germination and seedling grow of L.virgaurea.The results showed that the germination rate of L.virgaurea seeds pretreated at 4 ℃ for 24 h and-20 ℃ for 2 h increased significantly.The experiment also indicated that the germination index of L.virgaurea seeds did not change significantly within 2 h after-20 ℃ pretreatment, nor did it change significantly after 4 ℃ pretreatment for 24 h.However, the germination index of L.virgaurea seeds after 48 h and 72 h at 4 ℃ pretreatment was significantly lower than that of the control.The results further implied that with the extension of treatment time at 4 ℃,both root length and seedling length of L.virgaurea decreased.However, after a short time(0.5 h) at-20 ℃,the seed seedling length of L.virgaurea was significantly higher than that of the control after one year of storage, but there was no significant change in root length.As a whole, the seeds of L.virgaurea collected in 2018 had lower germination vitality than that collected in 2019,but the difference between two years in germination index and seedling length decreased after low temperature pretreatment.In conclusion, low temperature treatment will promote the germination of L.virgaurea seeds which have lower germination vitality with the prolonged storage time.However, long time of low temperature pretreatment will influence the growth of L.virgaurea seedlings.These results will provide basic data for the study of germination mechanism of L.virgaurea and the effective control of poisonous weeds in alpine grassland.