Abstract: The drought resistance of switchgrass seedling is a key factor limiting its growth in arid and semi-arid areas. Drought-resistance indicators and recovery growth after re-watering of switchgrass seedling were studied with split-unit design. Effects of persistent drought on the seedling growth and development of switchgrass differed from different varieties (lines). The Xiji 2 (from Alamo) had better drought-resistance than others. The growth of switchgrass seedling was restrained with the increasing of drought stress. The top of seedling was firstly restrained when drought stress was less than 10 days and soil moisture content (SWC) was higher than 3.7%. The seedling was completely restrained with the loss of leaf water and chlorophyll content reduced sharply, whereas root/shoot ratio, MDA content, the SOD, CAT and POD activities of seedling were increased when drought stress for 12 days. The top of seedling was dry and the new sprout grew after re-watering. Switchgrass would be dying and could not be revived after re-watering if drought stress was more than 12 days (more than 14 days for Xiji 2). Therefore, Xiji 2 might be a suitable variety recommended for use in the lack of rain areas and should be re-watered timely to rescue seedling after more than 10 days of drought stress and SWC was under 3.7%.

Key words: Switchgrass (Panicum virgatum), Drought stress, Re-watering, Tiller stage, Growth and development

摘要： 柳枝稷（Panicum virgatum）苗期的耐旱能力是其在干旱、半干旱地区生长的关键，为确定其耐旱能力，采用裂区试验设计对柳枝稷抗旱相关指标以及复水后幼苗的生长状况进行研究。结果表明：持续干旱胁迫对不同柳枝稷品种（系）的影响存在差异，其中以西稷2号（从Alamo中选育）的抗旱性较好。随干旱胁迫时间增加，其生长发育逐渐受到抑制，当胁迫时间低于10 d，土壤含水量高于3.7%时，其地上部生长受到一定程度的抑制，叶片失水，叶绿素含量急剧降低，根冠比、丙二醛（MDA）含量、以及抗氧化酶（SOD，CAT，POD）活性升高，此时复水柳枝稷幼苗能迅速恢复生长；当胁迫时间继续增大到12 d时，柳枝稷叶片失水严重，植株根冠比、叶片MDA含量，以及SOD，CAT，POD活性急剧升高，柳枝稷地上部干枯，此时复水可重新长出幼苗；但当胁迫时间超过12 d时（西稷2号超过14 d），将因缺水干旱死亡。因此，柳枝稷在降雨缺乏地区种植时，可选用西稷2号作为推广品种（系），且在持续干旱时间超过10 d，土壤含水量低于3.7%时，应及时复水救苗。

关键词: 柳枝稷, 干旱胁迫, 复水, 分蘖期, 生长发育