盐碱胁迫对少花蒺藜草种子萌发和幼苗生理特性的影响

Effects of saline-alkali stress on seed germination and seedling physiological characteristics of Cenchrus incertus

摘要:

少花蒺藜草(Cenchrus incertus)是科尔沁沙地入侵最为严重的恶性杂草之一，近年来在有盐渍化的区域零星分布。为了解少花蒺藜草耐盐能力及适应机制，本试验采用 2 种浓度的 NaCl与 4 种浓度 NaHCO₃模拟 8 种混合盐对少花蒺藜草种子及幼苗进行处理，观察种子的萌发情况并测定盐胁迫后幼苗的各项生理指标。结果表明：各比例混合盐均降低了种子发芽率、发芽势及发芽指数，当 NaCl 浓度为 0. 20 mol/L，NaHCO₃浓度为 0. 20 mol/L 及 NaCl 浓度为 0. 20 mol/L，NaHCO₃浓度为 0. 40 mol/L 时发芽指标值均为 0；在受到低浓度盐碱胁迫时，少花蒺藜草可通过提高抗氧化物酶活性及渗透调节物质含量来增强自身耐盐性，当混合盐 NaCl 0. 10 mol/L，NaHCO₃ 0. 20 mol/L 时少花蒺藜草叶片各项生理指标达到最大值，当 NaCl 与 NaHCO₃ 浓度均为 0. 20 mol/L 时少花蒺藜草无法正常生长；NaCl 与 NaHCO₃的交互作用对少花蒺藜草种子萌发及幼苗生理特性(除过氧化氢酶活性外)具有显著影响。

Abstract:

Cenchrus incertus is one of the most serious invasive weeds in Horqin Sandy Land. In recent years，the seeds and seedlings of C. incertus were distributed sporadically in salinized areas. In order to understand the salt toler- ance and adaptation mechanism of C. incertus ，two concentrations of NaCl and four concentrations of NaHCO₃ were used to simulate 8 kinds of mixed salt to treat the seeds and seedlings of C. incertus . The germination of seeds was observed and the physiological indexes of seedlings after salt stress were measured. The results showed that all the mixed salts decreased the germination rate，germination energy and germination index of seeds. When NaCl concen- tration was 0. 20 mol/L，NaHCO₃ concentration was 0. 20 mol/L，NaCl concentration was 0. 20 mol/L，or NaHCO₃ concentration was 0. 40 mol/L，germination index was 0. Under low concentration saline - alkali stress，C. incertus could enhance its salt tolerance by increasing the activity of antioxidant enzymes and the content of osmotic regula- tors. When the mixed salt NaCl was 0. 10 mol/L and NaHCO₃ was 0. 20 mol/L，the physiological indexes of of C. in- certus leaves reached the maximum. When the concentrations of NaCl and NaHCO₃ were both 0. 20 mol/L，C. incer- tus could not grow normally. The interaction between NaCl and NaHCO₃ had significant effects on seed germination and seedling physiological characteristics(except CAT activity)of C. incertus.