关键词: 胡麻, 油菜素内酯, 干旱胁迫, 产量, 生理特性

Abstract: To identify effective approaches for alleviating drought stress in flax and improve its drought resistance，the flax cultivar Jinya 10 was used as the experimental material. At the seedling stage，three treatments were established：normal control（CK），drought stress after spraying with water（DS），and drought stress after spraying with 0.1 mg/L brassinolide（BD）. After the drought treatment reduced the relative soil water content to 50%，water physiological traits，antioxidant enzyme activities，antioxidant substances，malondialdehyde（MDA），osmotic adjustment substances，endogenous hormone contents，yield，and yield components were determined under each treatment. The results showed that drought stress at the seedling stage significantly affected the physiology and yield of flax，resulting in a significant reduction of 26.01% in seed yield.Exogenous brassinolide alleviated the adverse effects of drought stress on flax.Seed yield in the BD treatment was 15.59% higher than that in the DS treatment，mainly because of the significant increases in capsules per plant and seeds per capsule.Exogenous brassinolide significantly increased the relative water content and water use efficiency of flax leaves under drought stress.Compared with the DS treatment，the activities of superoxide dismutase（SOD），peroxidase（POD），and catalase（CAT）in the BD treatment increased significantly by 9.26%，12.37%，and 9.14%，respectively，whereas MDA content decreased significantly by 17.33%. Exogenous brassinolide also significantly increased the contents of ascorbic acid（AsA），glutathione，soluble sugars，soluble proteins，proline，indole‐3‐acetic acid（IAA），gibberellin（GA），and zeatin（ZA）in flax leaves under drought stress，whereas starch content decreased significantly by 4.73%，thereby further enhancing drought resistance.These results indicate that exogenous brassinolide effectively mitigates the adverse effects of seedling‐stage drought stress on the physiology and yield of flax by increasing leaf relative water content and water use efficiency，enhancing antioxidant enzyme activities and antioxidant substance contents，reducing MDA and starch contents，and regulating the balance of key endogenous hormones.

Key words: Flax, Brassinolide, Drought stress, Yield, Physiological characteristics