Abstract:

In order to provide theoretical basis for sowing and seedling establishment under drought condition, the drought resistance and water requirement of switchgrass were investigated at germination and seedling establishment stages. The seeds of different switchgrass species (Pathfinder, Traiblazer and Alamo) were treated with low temperature (4℃) and 8 M sulfuric acid under different PEG concentrations (-0.1~-0.5 MPa). The water requirement thresholds of switchgrass seeds were evaluated at radicle emergence, plumule emergence and seedling establishment stages. Results showed that the times required for achieving the 50% radicle emergence, plumule emergence and seedling establishment of all seeds increased with environmental water potential decreasing. Water requirement threshold at seedling establishment stage was higher than that at radicle emergence and plumule emergence stages. Both low temperature treatment (4℃) and 8 M sulfuric acid treatment shorten the times required for achieving the 50% radicle emergence, plumule emergence and seedling establishment of all tested seeds, and enhanced the water requirement threshold in each stage. Pathfinder variety had lower requirement for environmental water potential than Trailblazer and Alamo varieties under the same treatment. Therefore, seedling establishment stage was the most sensitive to ambient water stress. Pathfinder variety showed the highest stress tolerance and drought resistance among three varieties.

Key words: Switchgrass, Seed treatment, Water stress, Drought tolerance, Critical water potential

摘要：

研究柳枝稷（Panicum virgatum）成苗期间的抗旱性及需水特性，可为其在干旱条件下播种保苗提供依据。采用不同浓度的聚乙二醇（-0.1~-0.5 MPa）模拟外界环境水分条件，用4℃低温冷冻化和8 M硫酸处理3个柳枝稷品种（Pathfinder，Traiblazer和Alamo）的种子，研究其成苗过程中种子萌动、萌发和出苗3个阶段的需水阈值。结果表明：随着环境水势的降低，种子群体萌动、萌发和出苗达50%概率的时间逐渐延迟；且各阶段的需水阈值不同，出苗阶段的最低。4℃低温冷冻化处理和8 M硫酸处理均使种子群体萌动、萌发和出苗达50%的时间缩短，各阶段需水阈值增大。在相同处理下，Pathfinder品种各阶段对环境水势的需求较Trailblazer和Alamo宽松。可见，柳枝稷种子出苗阶段对环境水分胁迫最为敏感，忍受胁迫能力最弱，抗旱性最弱； 其中Pathfinder品种忍受胁迫能力最强，抗旱性最强。

关键词: 柳枝稷, 种子处理, 水分胁迫, 耐旱性, 需水阈值