Abstract: In order to study the physiological response of Tamarix leptostachys Bunge, a rare native tree species, to salt stress in Hetao irrigation area, NaCl, Na₂CO₃ and NaHCO3 were selected as three stress salts, and three gradients of moderate (T1), severe (T2) and extremely severe (T3) were set up. There were altogether 10 treatments, including NaHCO₃ -T1, NaHCO₃ -T2, NaHCO₃ -T3, Na₂CO₃-T1, Na₂CO₃-T2, Na₂CO₃-T3, NaCl-T1, NaCl-T2, NaCl-T3, and salt-free sandy loam as control (CK). The two-year-old T. leptostachys seedlings were treated by pot experiment. The content of chlorophyll and malondialdehyde (MDA) and the activity of peroxide (POD), catalase (CAT) and root were determined to analyze the physiological response characteristics of T. leptostachys to three kinds of salt stress. The results showed that: ① Total chlorophyll contents of Na₂CO₃-T3 and NaCl-T3 treated for 40 d  decreased by 53% and 36%, respectively, compared with the corresponding treatment for 0 d, and showed a continuous decreasing trend with the extension of treatment. Other treatments showed a trend of decreasing firstly then increasing, which indicated  that extremely severe salt stress seriously affected the photosynthesis of T. leptostachys, while it could recover moderately in a short time under moderate and severe salt stress. ② The increase of MDA content under NaCl stress was the highest in all treatments, which indicated that the damage of NaCl stress to cell membrane system of T. leptostachys was more serious than those under NaHCO₃ and Na2CO3 salt stress. ③ With the prolongation of stress time, the activities of POD and CAT in different treatments showed a trend of increasing firstly then decreasing. ④ The root activity of T. leptostachys was gradually decreased with the increase of salt stress concentration. It was demonstrated that under moderate and severe salt stress, T. leptostachys showed strong adaptability and was suitable for popularization and application in saline-alkali areas. However, under extremely severe salt stress, it was seriously damaged, thus its application should be further evaluated. The present research provided a theoretical foundation for the popularization and application of T. leptostachys.

Key words: Tamarix leptostachys Bunge, salt stress, physiological response

摘要： 为研究河套灌区稀有乡土树种细穗柽柳(Tamarix leptostachys Bunge)对盐胁迫的生理响应，选择 NaCl、Na₂CO₃、NaHCO₃ 3种胁迫盐，设置中度 (T1)、重度 (T2)、极重度 (T3) 3个梯度处理，分别为NaHCO₃-T1、NaHCO₃-T2、NaHCO₃-T3、Na₂CO₃-T1、Na₂CO₃-T2、Na₂CO₃-T3、NaCl-T1、NaCl-T2、NaCl-T3，并设置无盐砂壤土为对照 (CK)，总计10个处理,通过盆栽试验对2年生细穗柽柳苗进行单盐胁迫处理40 d。测定不同处理的叶绿素、丙二醛 (malondialdehyde, MDA) 含量、过氧化物酶 (peroxidase, POD)、过氧化氢酶 (catalase, CAT) 活性及根系活力指标，分析细穗柽柳对3种盐胁迫的生理响应特征。结果表明，①Na₂CO₃ -T3处理和NaCl-T3 处理40 d的叶绿素总含量较相应处理0 d分别显著降低了53%和36%，且随着时间的延长呈持续递减趋势，其他盐胁迫及胁迫梯度处理组均呈先降低后升高趋势，说明极重度盐胁迫严重影响了细穗柽柳的光合作用，而中度和重度盐胁迫，细穗柽柳短期内能够适度恢复；②NaCl 胁迫在各梯度处理下MDA含量的增加均最多，表明 NaCl 胁迫对细穗柽柳细胞膜系统的伤害比 NaHCO₃ 和 Na₂CO₃ 盐胁迫更加严重；③随着胁迫时间的延长，不同盐处理不同胁迫梯度处理的POD 和 CAT 活性均呈现先升高后降低的趋势；④细穗柽柳的根系活力随盐胁迫浓度的增加逐渐降低。可见，在中、重度盐胁迫下，细穗柽柳表现出较强适应性，适宜推广应用；但在极重度盐胁迫下，受伤害严重，其应用需要进一步研究。结果为细穗柽柳的推广应用奠定理论基础。

关键词: 细穗柽柳, 盐胁迫, 生理响应