Abstract: Leymus chinensis is the dominant species in Songnen salt-alkali grassland of Northern China.The effects of temperature(20/10℃,30/20℃ and 35/25℃),salinity(NaCl:Na₂SO₄= 9:1),alkalinity(NaHCO₃:Na₂CO₃= 9:1) and their interactions on seed germination and seedling growth of Leymus chinensis were investigated.Results showed that seed germination rate,root length and leaf length all decreased with added salinity and alkalinity stress compared with other treatments.Seed germination and seedling growth were inhibited under stress of extreme temperature and salinity interactions or extreme temperature and alkalinity interactions.Low temperature inhibited seed germination with salinity<200 mmol·L^-1.Effects were aggravated by extreme high temperature with increased salinity.Under alkali stress,germination percentage and germination rate both decreased markedly by high temperature(35/25℃) even though the alkalinity was very low.Results indicate that seed germination and seedling growth of Leymus chinensis are affected by temperature,salinity,alkalinity and their interactions.The deleterious effect of alkali stress on seed germination and seedling growth of Leymus chinensis is more severe than salt stress.

Key words: Salt stress, Alkali stress, Leymus chinensis, Seed germination, Temperature, Seedling growth

摘要： 羊草(Leymus chinensis)是我国东北松嫩盐碱化草地上的建群植物。为明确羊草在种子萌发与幼苗生长阶段对盐、碱胁迫及与温度交互作用的响应,采用3个温度处理(20/10℃,30/20℃和35/25℃),并混合2种中性盐(NaCl:Na₂SO₄=9:1)与2种碱性盐(Na₂CO₃:NaHCO₃=9:1)分别模拟土壤盐、碱胁迫条件进行研究。结果表明:随着盐碱胁迫浓度的增加,羊草种子的发芽率、发芽速率、叶片长度与根系长度均呈下降趋势,且在碱胁迫下其降幅更大;另外这2种胁迫均对羊草幼苗根生长的抑制作用更强。温盐、温碱交互作用显著影响羊草种子的萌发与幼苗生长,其中30/20℃处理下羊草生长最好;在盐胁迫下,当盐浓度<200mmol·L^-1时,低温是影响种子萌发的主要因素,随着盐度继续增加,高温则加剧了盐胁迫对种子萌发的抑制作用;在碱胁迫下,即使碱浓度较低,高温与其交互作用也极大地加剧了对种子发芽的抑制。因此,盐、碱胁迫及温盐、温碱交互作用对羊草种子萌发与幼苗生长的抑制作用明显不同,碱胁迫及其与温度交互作用对羊草的伤害更大。

关键词: 盐胁迫, 碱胁迫, 羊草, 种子萌发, 温度, 幼苗生长