Investigation of the effect of planting date management on yield and growth traits of sesame cultivars in Dargaz region

Introduction
Food security is one of the major global challenges of the 21st century due to rapid population growth and increasing demand for food and vegetable oils. Improving agricultural productivity through sustainable management practices is therefore essential. Sesame (Sesamum indicum L.) is an important oilseed crop widely cultivated in arid and semi-arid regions. Its growth and productivity are highly influenced by environmental factors, especially temperature and moisture conditions (Weldermichael et al., 2025). Among agronomic practices, sowing date and cultivar selection are considered the most important factors affecting sesame growth, yield, and oil content. Previous studies have shown that delayed sowing can shorten the growth period and significantly reduce grain yield. However, the optimum sowing date varies depending on climatic conditions and cultivar characteristics (Hussain and Kumar, 2022). Therefore, this study was conducted to determine the best sowing date and suitable sesame cultivars for maximizing grain yield under the climatic conditions of Darrehgaz, Razavi Khorasan Province, Iran.

Materials and Methods
The experiment was conducted during the 2022–2023 growing season in Darrehgaz County, Razavi Khorasan Province, Iran (37°34′ N, 58°59′ E; 820 m above sea level). The experiment was arranged as a split-plot based on a randomized complete block design with three replications. Main plots consisted of three sowing dates (May 16, June 1, and June 17), while subplots included four sesame cultivars/genotypes: Local Landrace, Davarzan, Black Landrace, and Mohajer. Data were analyzed using SAS 9.4 software and mean comparisons were performed using Duncan’s multiple range test at the 5% probability level.

Results & Discussion
Results showed that sowing date and cultivar significantly affected days to capsule formation, plant height, stem diameter, number of capsules per plant, and oil percentage. In addition, the interaction between sowing date and cultivar significantly influenced flowering traits, capsule characteristics, thousand-seed weight, grain yield, and biological yield. Plant height decreased significantly with delayed sowing. The first sowing date produced the tallest plants (135.7 cm), whereas the third sowing date produced the shortest plants (84.7 cm). Among cultivars, Mohajer showed the greatest plant height (120.2 cm). The highest grain yield was obtained from Mohajer under the first sowing date with 3164 kg ha⁻¹. Under the same sowing date, Local Landrace and Black Landrace produced 2470 and 2446 kg ha⁻¹, respectively. In the second sowing date, Local Landrace and Black Landrace showed the best performance with 1921 and 1629 kg ha⁻¹. Under the third sowing date, Mohajer and Local Landrace performed relatively better than other cultivars. 1000-seed weight was highest in the first sowing date. Local Landrace, Mohajer, and Davarzan recorded 3.69, 3.59, and 3.25 g, respectively. Oil percentage also declined with delayed sowing, with the highest oil content observed in the first sowing date (38.87%) and the lowest in the third sowing date (37.48%). Mohajer had the highest average oil content (38.88%). Biological yield was strongly affected by the interaction of sowing date and cultivar. Mohajer and Local Landrace under the first sowing date produced the highest biological yields of 13,520 and 12,600 kg ha⁻¹, respectively, whereas Black Landrace under the third sowing date produced the lowest biological yield (2679 kg ha⁻¹). Overall, delayed sowing reduced sesame productivity because of shortened growth duration, limited canopy development, and exposure to unfavorable environmental conditions during reproductive stages.

Conclusion
The results indicated that early sowing significantly improved sesame growth, grain yield, biological yield, and oil percentage under the climatic conditions of Darrehgaz. Among the tested cultivars, Mohajer showed superior performance, especially under the first sowing date. Therefore, early sowing (May 16) along with cultivation of Mohajer cultivar is recommended for achieving maximum sesame productivity in semi-arid regions of northeastern Iran.

Acknowledgements
The authors gratefully acknowledge the assistance of the agricultural staff and farm workers involved in conducting this experiment.

Keywords
Sesame; Sowing date; Cultivar; Grain yield; Oil percentage; Semi-arid climate
References
Weldemichael, M. Y., Gebremedhn, H. M., Runo, S., & Gandhi, H. (2025). Molecular breeding for stress tolerance in sesame. Molecular Genetics and Genomics, 300(1), 69.
Hussain, M., & Kumar, A. (2022). Response of sesame (Sesamum indicum L.) cultivation to date of sowing. Flora and Fauna Jhansi, 29(2).