Effects of drought stress and zeolite application rates on yield, oil content, and antioxidant enzymes of sesame cultivars in arid regions of Iran

Abstract Drought stress is a significant environmental factor affecting sesame ( Sesamum indicum L.) yield and quality. This study was conducted as a split‐plot factorial experiment in a randomized complete block design with three replications at two experimental sites: Zabol and Iranshahr in two arid locations in southeastern Iran, Sistan and Baluchestan province, Iran. The main plot factor was drought stress, with three irrigation levels: a1 (regional irrigation), a2 (irrigation cessation at 50% flowering stage), and a3 (irrigation cessation at 50% podding stage). The subplot factors were sesame cultivars (Halil, Dashtestan, and Darab) and four zeolite application rates (0, 3, 6, and 9 tons/ha mixed with the soil before sowing). The studied traits included plant height, number of capsules per plant, number of seeds per capsule, 1000‐seed weight, seed yield, biological yield, harvest index, and antioxidant enzymes. The highest plant height (111.38 cm) was observed for the Dashtestan cultivar in Zabol under non‐stress conditions with 9 tons/ha zeolite application. The highest number of capsules (42.1) and biological yield (3.92 tons/ha) were obtained from Zabol under non‐stress conditions with 9 tons/ha zeolite application and the Darab cultivar. The highest number of seeds per capsule (69.96), 1000‐seed weight (3.63 g), and seed yield (1.53 tons/ha) were obtained from Iranshahr under non‐stress conditions with 9 tons/ha zeolite application and the Halil cultivar. Additionally, the highest activities of catalase, ascorbate peroxidase, guaiacol peroxidase, and polyphenol oxidase were obtained under severe stress conditions (irrigation cessation at 50% flowering stage) without zeolite application in Iranshahr with the Halil cultivar. The highest oil percentage was obtained under non‐stress conditions with 9 tons/ha zeolite application and the Darab cultivar in Iranshahr. Zeolite application, particularly at 9 tons/ha, significantly improved seed yield, oil content, and antioxidant enzyme activities under moderate drought ( p < 0.05). Among cultivars, Halil demonstrated superior performance under stress conditions, showing higher catalase and peroxidase activity. These findings highlight the potential of using zeolite and drought‐tolerant cultivars to enhance sesame productivity in water‐limited environments.