水杨酸对NaHCO_(3)胁迫下桂西北喀斯特地区青冈栎种子萌发的影响

Effects of salicylic acid on germination of Cyclobalanopsis glauca seeds under NaHCO_(3) stress in Karst area of northwest Guangxi

【目的】探讨外源水杨酸(SA)对NaHCO_(3)胁迫下青冈栎(Cyclobalanopsis glauca)种子萌发特征和生理特性的影响。【方法】研究两个SA浓度(0和0.50 mmol/L)和7个NaHCO_(3)浓度(0、24、48、72、96、120和144 mmol/L)共14个处理组合下,青冈栎种子萌发参数(发芽率、发芽指数和活力指数)、耐盐指数、相对盐害率、丙二醛(MDA含量)、抗氧化酶[超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)]活性以及渗透调节物质(可溶性糖、可溶性蛋白和游离脯氨酸)含量的变化。【结果】(1)无SA处理时,在各NaHCO_(3)胁迫浓度下,青冈栎种子萌发参数和耐盐指数均低于对照组,相对盐害率则显著高于对照组。经SA处理后,种子萌发参数和耐盐指数均高于无SA处理组,相对盐害率则低于无SA处理组;当NaHCO_(3)浓度为0~72 mmol/L时,萌发参数和耐盐指数高于对照组,且在NaHCO_(3)为72 mmol/L时,萌发参数和耐盐指数最高,而相对盐害率最低。(2)无SA处理时,随NaHCO_(3)浓度的增加,种子POD和CAT活性先增后减,SOD活性显著低于对照组,MDA含量迅速增加。经SA处理后,在各NaHCO_(3)胁迫浓度下,种子抗氧化酶活性显著高于无SA处理组,MDA含量显著低于无SA组;且在NaHCO_(3)为72 mmol/L时,SOD和POD活性最高。(3)无SA处理组,在NaHCO_(3)各胁迫浓度下,种子中渗透调节物质都高于对照组;经SA处理后,渗透调节物质有不同程度增加,且在NaHCO_(3)为72 mmol/L时,其渗透调节物质含量最高。【结论】在喀斯特地区进行青冈栎播种育苗时,用0.50 mmol/L外源SA浸种,对72 mmol/L NaHCO_(3)胁迫的缓解效应最好。

【Objective】This study aimed to alleviate NaHCO_(3)stress in Cyclobalanopsis glauca by investigating the effects of exogenous application of salicylic acid(SA)on the seed germination and physiological characteristics,under bicarbonate stress.【Method】Changes in germination rates and indexes,vigor indexes,salt tolerance indexes,relative salt damage rates,malondialdehyde(MDA)content,antioxidant superoxide dismutase(SOD),peroxidase(POD)and cata-lase(CAT)activities as well as osmotic adjustment substances agents(proline,soluble sugar and soluble protein)content were assessed in C.glauca seeds under NaHCO_(3)(0,24,48,72,96,120 and 144 mmol/L)stress and exogenous application of salicylic acid(SA:0 and 0.50 mmol/L)treatment.【Result】①Germination parameters and salt tole-rance were lower,and salt damage rates were significantly higher under NaHCO_(3)stress,without SA,in C.glauca seeds compared to those of the control.However,seeds had higher germination parameters,a higher salt tolerance index,and lower relative salt damage rates under NaHCO_(3)stress with SA compared to those without SA.The seed germination parameters and a salt tolerance index were always higher under 0-72 mmol/L NaHCO_(3)stress with SA treatment compared with the control group.The germination parameters and a salt tolerance index were maximal,and the relative salt damage rate was minimal under 72 mmol/L NaHCO_(3)stress with 0.50 mmol/L of SA treatment.②The POD and CAT activities of seeds without SA initially increased,then decreased with increasing NaHCO_(3)concentrations,and SOD activity was significantly lower than that of the control group,whereas the MDA content rapidly increased.Antioxidant enzyme activities and MDA contents were significantly higher and lower,respectively,under NaHCO_(3)stress with,than without SA.The activities of SOD and POD were maximal in 72 mmol/L of NaHCO_(3)with 0.50 mmol/L of SA.③The contents of osmotic adjustment agents were high under NaHCO_(3)stress without SA,and increased under NaHCO_(3)stress with SA compared with the control.The contents of osmotic adjustment agents were maximal under 72 mmol/L of NaHCO_(3)with 0.50 mmol/L of SA.【Conclusion】The effects of 72 mmol/L NaHCO_(3)stress on C.glauca seeds sowed and bred in the Karst areas were alleviated after immersion in 0.50 mmol/L exogenous SA.