Abstract:

The seed physiological qualities of three switchgrass ecotypes (Panicum virgatum L.) were evaluated in laboratory by the simulation of water potentials using polyethyleneglycol-6000 (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa). The physiological indices including germination percentage, normal seedlings, ungerminated fresh seeds, dead seeds, germination index, seed vigor index, root length, shoot length and leaf area were measured. Results showed that the seed germination percentage, germination index, vigor index and seedling growth indexes of three switchgrass varieties increased under water stress, while the normal seedlings rate significantly decreased with osmotic potential decreasing. Fresh ungerminated seeds increased significantly, and dead seeds also increased compared to control. However, there was no significant difference among treatments. These results indicated that the secondary dormancy of switchgrass seed was induced in the treatment of lower osmotic potential. The effects of water stress on seed germination and seedling growth was severe when osmotic potential was below -0.4 MPa. The adaptability and resistance of switchgrass to water stress differed between tested cultivars. The adaptabilities of three switchgrass ecotypes to water stress were ordered as Alamo (lowland) >Cave-in-Rock (intermediate) >Sunburst (upland).

Key words: Switchgrass, Water stress, PEG-6000, Germination, Seedling growth

摘要：

采用聚乙二醇（PEG-6000）模拟不同水势（0.0，-0.2，-0.4，-0.6，-0.8和-1.0 MPa），在25℃条件下采用纸上发芽法测定发芽率、正常幼苗数、新鲜未发芽种子数、死种子数、发芽指数、活力指数、根长、苗长和叶面积等生理指标，研究水分胁迫对3个生态型的柳枝稷（Panicum virgatum L.）种子萌发及幼苗生长的影响。结果表明：3个品种柳枝稷种子发芽率、发芽指数、活力指数及幼苗生长指标均随水分胁迫程度的增加而下降，且基本符合“S”型曲线，而正常幼苗数随渗透势的下降显著降低，新鲜未发芽种子数显著增加，死种子数较对照增加，但各处理间差异不显著，说明降低渗透势可诱导柳枝稷种子二次休眠，当渗透势在-0.4 MPa时，水分胁迫对种子发芽及幼苗生长的影响较严重，不同品种柳枝稷种子对水分胁迫的适应性和抵抗力有一定差异，3个生态型的柳枝稷种子对水分胁迫的适应性强弱为Alamo（低地型）>Cave-in-Rock （中间型）>Sunburst（高地型）。

关键词: 柳枝稷, 水分胁迫, PEG-6000, 萌发, 幼苗生长