Abstract: Using the sesame cultivar Shangzhi 196 as experimental material，a pot experiment was systematically conducted to investigate the regulatory effects of different concentrations（0，0.25，0.50，0.75 mg/L）of 2，4‐epibrassinolide（EBR）on sesame seedling growth and physiology under gradient drought stress［normal moisture（W1），mild drought（W2），and severe drought（W3）］.The results demonstrated that as soil water content decreased，sesame growth was inhibited，manifested by reduced plant height，increased root‐to‐shoot ratio，and suppressed aboveground biomass accumulation.After 12 days of stress treatment，under W2 and W3 conditions，the average plant height decreased by 6.70% and 28.88% respectively compared to W1，while the root‐to‐shoot ratio increased by 17.54% and 67.69% correspondingly.Transpiration rate and stomatal conductance showed decreasing trends，intercellular CO₂ concentration generally exhibited an increasing trend，and both malondialdehyde and proline contents increased，while antioxidant enzyme activities declined as the soil moisture content decreased.The effects of EBR varied depending on stress severity and growth stage.Appropriate EBR concentrations effectively increased sesames’plant height，aboveground dry weight and root dry weight，enhanced photosynthetic capacity，reduced membrane lipid peroxidation，and significantly improved drought resistance.Principal component analysis revealed that under mild drought stress，foliar application of 0.50 mg/L EBR most effectively enhanced drought tolerance，while 0.25 mg/L EBR showed better efficacy under severe drought conditions.

Key words: Sesame；Drought stress； 2, 4‐epibrassinolide（EBR）； Physiological characteristics；Photosynthetic characteristics

摘要： 为提高芝麻苗期应对干旱的能力，实现干旱条件下芝麻稳产、高产，以商芝196为试材，通过盆栽试验，系统研究不同质量浓度（0、0.25、0.50、0.75 mg/L）2，4-表油菜素内酯（EBR）对梯度干旱胁迫［正常水分（W1）、轻度干旱（W2）、重度干旱（W3）］下芝麻苗期生长及生理的调控效应。结果表明，随土壤水分含量减少，芝麻生长受到抑制，表现为株高降低，根冠比升高，地上部生物量积累受到抑制，其中胁迫处理12 d，W2 和W3 条件下平均株高较W1 分别下降6.70%、28.88%，根冠比则相应增加17.54%、67.69%；蒸腾速率、气孔导度呈下降趋势，胞间CO2浓度总体呈上升的趋势，丙二醛和脯氨酸含量增加，抗氧化酶活性降低。不同胁迫程度和不同生育进程下EBR作用效果不同，适宜浓度的EBR处理能有效增加芝麻幼苗的株高、地上部干质量及根干质量，增强光合能力，降低膜脂过氧化程度，有效提高芝麻幼苗的抗旱能力。通过主成分分析结果可知，轻度干旱胁迫下喷施0.50 mg/L EBR能有效提升芝麻幼苗的耐旱性，重度干旱胁迫下喷施0.25 mg/L EBR效果更佳。

关键词: 芝麻；干旱胁迫；2, 4-表油菜素内酯（EBR）；生理特性；光合特性