目的 研究外源吲哚-3-乙酸（indole-3-acetic acid，IAA）对NaCl胁迫下甘草幼苗生长调节及总黄酮含量的影响。方法 采用丙酮法提取叶片叶绿素含量；采用超声提取法、紫外分光光度法测定甘草幼苗总黄酮含量；火焰分光光度计分别测定Na^＋和K^＋的含量；氯电极直接电位法测定Cl⁻的含量；硫代巴比妥酸法测定丙二醛（malondialdehyde，MDA）的含量；苯酚法测定可溶性糖的含量；磺基水杨酸法测定脯氨酸（proline，Pro）的含量；愈创木酚比色法测定过氧化物酶（peroxidase，POD）的活性；氮蓝四唑光化还原法测定超氧化物歧化酶（superoxide dismutase，SOD）活性；紫外吸收法测定过氧化氢酶（catalase，CAT）的活性；采用Microsoft Excel 2019进行数据处理和分析，以SPSS19.0统计软件对数据进行方差分析。结果 施加10～20 mmol/L外源IAA能显著降低NaCl胁迫对甘草幼苗的伤害，其中外源IAA浓度为15 mmol/L时效果最佳。NaCl胁迫条件下，施加15 mmol/L的外源IAA时甘草幼苗长势最为健壮，根长、茎长等生长量增加明显。外源IAA浓度为15 mmol/L时，影响渗透调节的K⁺及K⁺/Na⁺浓度增加较显著，Na⁺、Cl⁺浓度相较于无NaCl胁迫处理时明显降低；外源IAA浓度为15 mmol/L时可增加甘草幼苗光合叶绿素含量，同时降低了甘草幼苗内可溶性糖、Pro和MDA的含量；外源IAA浓度为15 mmol/L时可提高甘草幼苗内抗氧化酶（POD、SOD、CAT）的活性；外源IAA浓度为15 mmol/L时可促进甘草幼苗有效成分总黄酮的积累，有利于提高甘草幼苗的抗性。结论 NaCl胁迫条件下，施加适宜浓度外源IAA可提高甘草幼苗生长量、促进有效成分积累、降低盐害带来的伤害、促进该逆境下甘草幼苗的生长。

Objective To study the effects of exogenous indole-3-acetic acid (IAA) on the growth regulation and total flavonoids content of Glycyrrhiza uralensis seedlings under NaCl stress. Methods Chlorophyll content in leaves was extracted by acetone method; The content of total flavonoids in Glycyrrhiza uralensis seedlings was determined by ultrasonic extraction and ultraviolet spectrophotometry. The contents of Na⁺ and K⁺ were determined by flame spectrophotometer. Determination of cl content by direct potentiometry with chlorine electrode; The content of malondialdehyde (MDA) was determined by thiobarbituric acid method. Determination of soluble sugar content by phenol method; The content of proline (Pro) was determined by sulfosalicylic acid method. The activity of peroxidase (POD) was determined by guaiacol colorimetry. The activity of superoxide dismutase (SOD) was determined by nitroblue tetrazole photochemical reduction method. The activity of catalase (CAT) was measured by ultraviolet absorption method. Microsoft Excel 2019 was used for data processing and analysis, and SPSS19.0 statistical software was used for data analysis of variance. Results The experiments showed that the application of 10—20 mmol/L exogenous IAA significantly reduced the damage to licorice seedlings under NaCl stress, with the best effect observed at an exogenous IAA concentration of 15 mmol/L. Under NaCl stress conditions, the application of 15 mmol/L exogenous IAA resulted in the strongest growth of licorice seedlings, with significant increases in root and stem length. When the concentration of exogenous IAA is 15 mmol/L, the concentration of K⁺ and K⁺/Na⁺ that affect osmotic regulation increases significantly. The concentrations of Na⁺ and Cl⁺ were significantly reduced compared to the treatment without NaCl stress; When the concentration of exogenous IAA is 15 mmol/L, it can increase the photosynthetic chlorophyll content of licorice seedlings, while reducing the content of soluble sugars, Pro, and MDA in licorice seedlings; When the concentration of exogenous IAA is 15 mmol/L, it can increase the activity of antioxidant enzymes (peroxidase, superoxide dismutase, catalase) in licorice seedlings; When the concentration of exogenous IAA is 15 mmol/L, it can promote the accumulation of total flavonoids in licorice seedlings, which is beneficial for improving their resistance. Conclusion Under NaCl stress conditions, the application of appropriate concentrations of exogenous IAA can increase the growth of licorice seedlings, promote the accumulation of effective components, reduce the damage caused by salt damage, and promote the growth of licorice seedlings under this stress.

R286.2

药用植物新品种引进筛选与示范推广项目（00004901）