BACKGROUND: In drought stress conditions, the use of plant growth regulators such as salicylic acid can be considered as a strategy to mitigate the adverse effects of drought stress on plants. OBJECTIVES: This study aims to investigate the biochemical effect of growth regulator on the quantitative and qualitative yield of two wheat varieties, bread and rainfed, in Khuzestan province under end-of-season drought stress conditions. METHODS: Current research was done via factorial experiment according complete randomized block design with three replications in the greenhouse of Islamic Azad University, Ahvaz branch, in 2018. The treatment included two levels of salicylic acid [control (zero application) and 1 mM foliar spray], two irrigation regimes [watering until the end of the season and cessation of watering at the seed filling stage (Zadox stage 69)]; and two drought-resistant wheat varieties: Chamran 2 and Karkheh. RESULT: The results showed that end-season drought stress significantly affected the studied traits. The cessation of irrigation at the seed filling stage led to a significant increase in catalase, proline, protein, remobilization, and a decrease in chlorophyll index and stomatal conductance. However, the application of salicylic acid regulated these traits and positively influenced both the quantity (seed yield) and quality (gluten) of the seed, increasing them by 7.30% and 8.05%, respectively. CONCLUSION: The findings of this study suggest that salicylic acid application can mitigate the adverse effects of drought stress and enhance growth and yield under favorable conditions while reducing decline under stress conditions. Therefore, the use of salicylic acid as a growth regulator is recommended in the Chamran 2 variety. Manuscript profile