稀土微肥对盐胁迫下菘蓝种子萌发及幼苗抗氧化系统的影响

Effects of rare earth micronutrients on seed germination and antioxidant system of Isatis indigotica Fort.under salt stress

【目的】研究外源稀土微肥对盐胁迫下菘蓝种子萌发、幼苗生长及幼苗抗氧化系统的影响,探究稀土微肥对菘蓝盐胁迫伤害的缓解效应,为稀土微肥在药用植物栽培中的应用提供理论依据。【方法】以蒸馏水为对照(CK),施加0.05%~0.50%的外源稀土微肥对100 mmol/L NaCl胁迫下的菘蓝种子及幼苗进行缓解处理,测定种子的发芽率、发芽势、发芽指数和活力指数,幼苗的株高、根长和鲜重以及幼苗中超氧阴离子自由基(O-2·)产生速率、过氧化氢(H2O2)含量、抗氧化酶活性等指标。【结果】100 mmol/L NaCl胁迫下,菘蓝种子的发芽率、发芽势、发芽指数和活力指数分别较CK下降66.67%、65.58%、58.30%和72.79%;幼苗的株高、根长、鲜重和干重分别下降41.06%、44.83%、40.76%和42.06%;幼苗中的O-2·产生速率和H2O2含量分别升高163.21%和121.13%,超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性分别升高77.78%、24.78%和51.47%,过氧化氢酶(CAT)活性下降57.47%;在施加0.05%~0.50%的外源稀土微肥后,菘蓝种子的各项发芽指标、幼苗生长及抗氧化生理指标优于100 mmol/L NaCl处理,尤以0.30%稀土微肥处理的种子发芽指标和幼苗生长指标最高,幼苗中的O-2·产生速率和H2O2含量最低,抗氧化酶(SOD、CAT、POD、APX)活性最高。盐胁迫下,稀土微肥与幼苗中的O-2·产生速率和H2O2含量呈负相关,与抗氧化酶活性呈正相关;O-2·产生速率与H2O2含量呈极显著正相关(P<0.01,下同),O-2·产生速率和H2O2含量均与SOD、POD和CAT活性间呈极显著负相关。【结论】施加适当浓度的稀土微肥可提高盐胁迫下菘蓝种子的萌发能力,促进幼苗生长,增强幼苗中抗氧化酶活性,降低活性氧积累,缓解盐胁迫伤害,尤以0.30%的稀土微肥处理缓解效果较佳。

【Objective】The effects of exogenous rare earth micronutrients on seed germination,seedling growth and seedling antioxidant system of Isatis indigotica Fort.under salt stress were studied,and the alleviating effect of rare earth micronutrients on salt stress injury of I.indigotica was explored,so as to provide theoretical basis for the application of rare earth micronutrients in the cultivation of medicinal plants.【Method】With distilled water as control(CK),0.05%-0.50%of the exogenous rare earth micronutrient were applied to I.indigotica seeds and seedlings under 100 mmol/L NaCl stress,the germination rate,germination potential,germination index and vigor index of seeds,seedling plant height,root length and fresh weight,superoxide anion radical(O-2·)productive rate,hydrogen peroxide(H2O2)content in seedlings and antioxidant enzyme activity were determined.【Result】Under 100 mmol/L NaCl stress,the germination rate,germination potential,germination index and vigor index of I.indigotica seeds decreased by 66.67%,65.58%,58.30%and 72.79%,respectively,compared with CK.The plant height,root length,fresh weight and dry weight of seedlings decreased by 41.06%,44.83%,40.76%and 42.06%,respectively.The O-2·productive rate and H2O2 content in seedlings increased by 163.21%and 121.13%,the activity of superoxide dismutase(SOD),peroxidase(POD)and ascorbate peroxi-dase(APX)increased by 77.78%,24.78%and 51.47%,and the activity of catalase(CAT)decreased by 57.47%.After applying 0.05%-0.50%exogenous rare earth micronutrients,I.indigotica seeds germination index,seedling growth and antioxidant physiological indexes were superior to the tendency for 100 mmol/L NaCl treatment,especially in the 0.30%rare earth micronutrients treatment,the seed germination and seedling growth indicators were the highest,the O-2·productive rate and H2O2 content were the lowest,and the activities of antioxidant enzymes(SOD,CAT,POD,APX)were the highest.Under salt stress,rare earth micronutrients was negatively correlated with O-2·productive rate and H2O2 content in seedlings,and positively correlated with antioxidant enzyme activity.The O-2·productive rate was extremely significantly positively correlated with the H2O2 content(P<0.01,the same below),and the O-2·productive rate and H2O2 content were extremely significantly negatively correlated with the activities of SOD,POD and CAT.【Conclusion】The application of proper concentration of rare earth micronutrients can improve the germination ability of I.indigotica seeds under salt stress,promote the growth of seedlings,enhance the activity of antioxidant enzyme system in seedlings,reduce the accumulation of reactive oxygen,and alleviate the damage of salt stress,especially 0.30%treatment has sound alleviating effect.