Insufficient attention has been paid to the physiological responses of sesame to drought and it is unclear if exogenous plant growth regulators are beneficial to drought-stressed sesame. Thus, a field study was conducted on seven Sesamum indicum genotypes affected by two levels of irrigation (60 and 80% depletions in available soil water) and by foliar-applied salicylic acid (SA; 0 and 0.6 mM). Water deficit led to depressions in net photosynthetic rate, stomatal conductance, leaf area index, chlorophyll a, b, and total chlorophyll contents, maximum quantum efficiency of PSII, and plant dry matter and seed yield, despite increases in carotenoid concentration, superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase activities. SA was found beneficial in ameliorating the depressions in all of the above characteristics, indicating that it could be applied for lessening the harmful effects of the drought stress.

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Core Ideas Osmoregulation helps sesame withstand drought. Diversity exists in sesame genotypes response to drought. Salicylic acid benefits sesame grain yield. Drought stress poses a major threat to plant growth, development, and yield. Salicylic acid (SA) is one of the endogenous plant growth regulators that plays a key role in plant resistance against environmental stresses, including drought. A 2‐yr field experiment was performed to assess the modifications in compatible solutes, water status, and seed yield of sesame (Sesamum indicum L.) under drought stress and to see whether foliar application of SA ameliorates these modifications. For this purpose, seven sesame genotypes, namely Yekta, Shiraz, Naz‐Takshakhe, Dashtestan, Isfahan, Varamin, and Oltan, were watered after 60% (control) and 80% (drought) depletion of the available soil water in the presence of two SA concentrations (0 and 0.6 mM). Drought was found to lead to significant reductions in leaf water potential (LWP), relative water content (RWC), seeds/capsule, capsules/plant, seeds/m2, 1000‐seed weight, and, thereby, seed yield and oil content. Significant increases were observed in proline and total soluble carbohydrates (TSC) concentrations in response to drought. Exogenously applied SA alleviated the stress impacts by enhancing all the studied attributes under both moisture conditions, more notably under water deficit conditions. The genotypes exhibited clear differences in their responses to water deficit and SA application. The genotype Yekta showed higher stability in terms of the majority of the studied attributes against drought stress. With the environmental conditions experienced in these 2 yr, osmoregulatory measures were found to serve as indicators of resistance to drought stress while SA seemed effective in the enhancing of these measures in this oilseed crop.