不同环境因素对大赖草种子萌发的影响

针对大赖草种群的自然更新率低、实生苗少的状况，研究了水分、盐分和埋深处理对大赖草种子萌发的影响。结果表明，大赖草种子具有快速吸水的特性；较低浓度（5％～10％）的PEG处理对层积8周后大赖草种子萌发率影响不明显，随着PEG浓度的升高，萌发抑制作用增强；盐分对其层积8周后种子的萌发具有明显抑制作用，在0．2mol／LNaCl溶液中仅有17％的种子萌发，而将盐溶液中处理15d的种子转移至蒸馏水中后，种子恢复萌发率随盐浓度升高而升高；沙埋深度的增加使其种子的萌发率呈先上升后下降的趋势，当沙埋深度为4cm时，种子萌发率最高为30％。经综合分析，干旱少雨、盐碱及风蚀沙埋的自然环境是大赖草种子在自然状态下萌发困难的主要因素。

Effects of Different Environmental Factors on the Seed Germination of Leymus racemosus

The seed germination characteristics of Leymus racemosus under different water supply,salini- ty （NaC1） and buried-depth were studied on the basis of slow renewal rate of the community of L. racemo- sus and its scarce seedlings. The results indicated that the seeds had the characteristics of rapid absorbing water. Lower concentration of PEG treatment （5 %- 10 ~） had no significant effect on the seed germina- tion rate after being stratified for 8 weeks. The percentage of seed germination inhibitory effect increased with the increase of PEG concentrations. Salinity had significantly inhibitory effect on the germination of the seeds which stratified for 8 weeks. There were only 17~ germinated seeds in 0.2 mol/L of NaCI solu- tion. However,when the seeds treated in NaC1 solution for 15 d were transferred to distilled water,the re- covery germination rate of the seeds increased with the increase of NaC1 concentration;the increase of bur- ied-depth of the seeds promoted the seed germination rate first to go up then go down. When buried-depth was 4 em, the highest germination rate of the seeds was 30~. Comprehensive analysis showed that the drought, salinity and erosion of sand burial in natural environment are the main factors to affect the germi- nation of L. racemosus seed in the natural habitat.