目的：研究不同程度干旱胁迫下硅对甘草种子萌发和幼苗生长阶段的调控效应及其最佳浓度。方法：通过水培发芽试验，采用不同浓度PEG-6000水溶液模拟干旱胁迫环境，根据生产实践设置较多水平的干旱胁迫（0%、5%、10%、15%、20%、25%、30% PEG-6000），设置了3个硅（K₂SiO₃）浓度（0、1、3mM）。结果：轻中度（5%-15%PEG）干旱胁迫对甘草种子萌发和幼苗生长没有明显的抑制，重度（≥20% PEG）干旱胁迫明显抑制甘草生长、降低其幼苗生物量。施硅能显著促进试验所设条件下甘草种子萌发及其幼苗生长，且这种促进效应因硅浓度和干旱胁迫程度而异，具体表现为：在所有干旱条件下1mM硅的促进作用明显强于3mM；就1mM硅而言，在重度（≥20%PEG）干旱胁迫下的促进作用强于轻中度（5%-15%PEG）干旱胁迫。结论：硅参与了干旱条件下甘草生长发育的生理生化进程，从而缓解干旱胁迫，促进其生长，但硅具体参与了哪些生理生化过程，需要进一步证实。

This study aimed at investigating the regulatory effects of silicon on the seed germination and seedling growth of G.uralensis and the optimum concentration of silicon under different levels of drought stress.A water-culture experiment was conducted,while various levels of drought stress were stimulated by 0%,5%,10%,15%,20%,25% and 30% PEG-6000 according to production practice and three different concentrations(0,1,3mM)of K₂SiO₃.As a result,mild and moderate drought stress(5%-15% PEG)presented no significant inhibitory effects on the seed germination and seedling growth of G.uralensis,while severe drought stress(≥20% PEG)significantly suppressed its growth and reduced its biomass.Silicon additions significantly promoted the seed germination and seedling growth of G.uralensis,which was dependent on its concentration and the level of drought stress.Specifically,the promotive effects of 1mM silicon was stronger than those of 3mM silicon under all drought stress levels.Under the condition of 1mM silicon,the promotive effect on severe drought stress(≥20% PEG)was stronger than that on mild and moderate drought stress(5%-15% PEG).It was concluded that silicon was directly involved in the physiological process of seed germination and seedling growth of G.uralensis under drought stress with the relief of drought damage and the promotion of its growth.However,the exactly physiological and biochemical processes involved in silicon still needed confirming in the further researches.

国家自然科学基金委地区科学基金项目（31260304）：硅提高盐胁迫下甘草药材产量和甘草酸含量的潜力及机制，负责人：张新慧；国家自然科学基金委地区科学基金项目（31460330）：旱盐逆境下硅提高甘草综合水分利用效率的生理生态机制，负责人：张新慧。