外源 Si 对盐胁迫下甘草幼苗形态及生理指标的影响

摘要

In this study,a water culture experiment was conducted to investigate the effect of silicon addition on the morphological indicators (radicle,seed germ)and physiological indicators [membrane permeability,ma-londialdehyde (MDA)level and peroxidase activities]of Glycyrrhiza uralensis seedlings under salt stress.Two NaCl concentrations (100 and 200 mmol/L)and six Si levels (0,0.4,0.8,1.2,1.6 and 2.0 mmol/L)were set as treatments in the experiment.Potassium silicate (K2 SO4 )was used as the source of Si.The Si addition can effectively increase the length and dry weight of germ and radicle of G.uralensis seedlings under salt stress.Under 100 mmol/L NaCl,the 0.4 mmol/L Si treatment promoted radicle growth the most among all the Si treatments,while under 200 mmol/L NaCl,the 0.8 mmol/L Si treatment promoted radicle growth the most.Exogenous Si addition was also able to increase the peroxidase activity and proline content,and reduce the levels of MDA under salt stress.In conclusion,G.uralensis showed enhanced osmotic stress resistance and reactive oxygen scavenging capacity under salt stress when exogenous Si was added to the culture medium and Si addition alleviated growth suppression of G.uralensis seedlings caused by salt stress.%为深入了解 Si 对盐胁迫下甘草幼苗的影响，本实验采用培养皿滤纸床进行发芽试验，以乌拉尔甘草幼苗为试验材料，在两种浓度 NaCl 溶液胁迫下设置不同浓度的硅溶液对甘草幼苗进行处理，通过测定幼苗形态（胚根、胚芽）及生理（质膜相对透性、丙二醛和过氧化物酶）指标，以探讨在盐胁迫下外源硅对甘草幼苗形态及生理指标的影响。结果表明，在 NaCl 胁迫下，加入硅（Si）溶液后可以有效增加幼苗胚芽和胚根的长度及重量。在低盐（100 mmol／L）胁迫下，Si 浓度为0．4 mmol／L 时对胚根生长的促进最强；在高盐（200 mmol／L）胁迫下，Si 浓度为0．8 mmol／L 时对胚根生长的促进作用最强。外源 Si 也不同程度提高了过氧化物酶活性、渗透调节物质脯氨酸含量，以及丙二醛含量和质膜相对透性。由此可见，在盐胁迫条件下，加入适宜浓度的外源硅，可以通过保持一定的抗渗透胁迫能力和清除活性氧的能力，进而保持膜的稳定，来缓解盐胁迫对甘草幼苗生长的抑制作用。