Abstract: In order to explore the optimal brassinolide (BR) concentration for repairing salt-stressed damage,Leymus secalinus ‘Jinbei’ was treated with 500 mmol·L^-1 NaCl for 15 days,and then was sprayed with BR of different concentrations (0.05,0.10,0.15,0.20 μmol·L^-1). Through the measurement and analysis of photosynthetic and physiological indexes of L.secalinus seedlings,the repairing effects of brassinolide on salt-stressed was investigated. The results showed that the phenotype and physiology of L.secalinus reached the degree of damage under 500 mmol·L^-1 NaCl stress,and BR could play a repairing role. Na ⁺and K⁺ were sensitive to BR,and K⁺/Na⁺ increased by 49.85% (P<0.05). After spraying BR,the content of superoxide anion free radical (O^-₂) and relative conductivity was decreased significantly,the activities of superoxide dismutase (SOD) was increased significantly,the activities of catalase (CAT) and peroxidase (POD) did not increase significantly,the chlorophyll content was increased,but the net photosynthetic rate was increased slowly. The above results showed that BR treatment could regulate ion transport and increase osmotic regulatory substances in leaves to resist the damage caused by ion stress,enhance antioxidant defense and reduce the oxidative damage of cells,so as to repair the damage caused by salt stress. 0.15 μmol·L^-1 BR treatment had the best repairing effects on L.secalinus under salt stress.

Key words: Leymus secalinus, Brassinolide, Salt stress, Photosynthetic physiology, Principal component analysis

摘要： 为探究油菜素内酯(Brassinolide，BR)对盐胁迫赖草的修复作用，本研究采用盆栽模拟试验，以‘晋北’赖草(Leymus secalinus ‘Jinbei’)为材料，用不同浓度(0.05，0.10，0.15，0.20 μmol·L^-1)的BR喷施盐(500 mmol·L^-1NaCl)胁迫的赖草叶片，通过对赖草幼苗光合生理指标的研究，筛选修复盐胁迫损伤的最适BR浓度。结果表明，500 mmol·L^-1NaCl胁迫后，对赖草表型及生理方面都达到了损伤的程度，不同浓度的BR处理盐胁迫后的赖草，能起到修复作用。Na⁺，K⁺对BR的作用比较敏感，K⁺/Na⁺提高了49.85%，效果显著(P<0.05)；BR喷施后，超氧阴离子(Superoxide anion free radical，O^-₂)含量、相对电导率显著降低，超氧化物歧化酶(Superoxide dismutase，SOD)活性显著降低，过氧化氢酶(Catalase，CAT)，过氧化物酶(Peroxidase，POD)活性增加不明显，叶绿素含量增加，但净光合速率提高缓慢。综合分析，BR处理主要通过调节离子运输抵抗离子胁迫带来的伤害，增加叶片渗透调节物质、降低活性氧损伤，保护细胞膜，达到修复盐胁迫的作用，且用0.15 μmol·L^-1BR对赖草的修复效果最佳。

关键词: 赖草, 油菜素内酯, 盐胁迫, 光合生理, 主成分分析