Regulatory Effect of 2,4-Epibrassinolide on the Growth and Physiology of Sesame Seedlings under Drought Stress

LÜ Shuli; DING Fang; TIAN Zhuangbo

doi:10.15933/j.cnki.1004-3268.2025.10.007

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.