Document Type : Research Paper - Oil seed
Authors
1 Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
2 Assistant Professor at Bushehr Province Agriculture and Natural Resources Research and Education Center
3 Assistant professor, Soil and Water Science Research Department, Bushehr Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Borazjan, Iran
4 1- Assistant Professor, Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
5 Crops and Horticultural Science Research Department, Khuzestan Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Dezful, Iran
Abstract
Introduction
Sesame (Sesamum indicum L.) is an oilseed crop grown for its edible oil in dry and semi-arid conditions worldwide. Because of its minimal input requirements, it is a great crop to cultivate in rotation with other crops. In the context of irrigation planning and determining the optimal time to cut-off irrigation at the end of sesame cultivation in the Bushehr region, a major sesame production hub, there has been no research conducted on the available cultivars or newly introduced lines. This study hypothesises that by reducing water availability during non-critical stages of drought tolerance, it may be possible to enhance irrigation water productivity in existing sesame cultivars and lines while maintaining seed and oil yields. To test this hypothesis, the present research was designed and implemented.
Materials and Methods
The current experiment was carried out in 2022 and 2023 growing seasons at the Agricultural and Natural Resources Research Center fields in Borazjan, Bushehr, Iran. The region is characterized as hot and arid, and the average yearly precipitation (over a 30-yr period), which occurs mostly during the autumn and winter months, is 250 mm for the site. This study investigated the effect of different irrigation regimes—full irrigation (80 mm evaporation) and low irrigation (160 mm evaporation)—and the timing of irrigation cut-off on yield and yield components, seed oil content, oil yield and irrigation water productivity in two sesame genotypes: Dashtestan 2 cultivar and promising line number 7. The cut-off timings were as follows: beginning of flowering, beginning of capsule formation, and mid-capsule formation. A split-split-plot design was used, with irrigation regime as the main plot, irrigation cut-off timing as the sub-plot, and genotype as the sub-sub-plot, arranged within a randomised complete block design with three replications.
Results and Discussion
As anticipated, the reduction in water availability under the low irrigation regime led to a significant decrease in seed yield components across both genotypes. Results indicated that for the two primary traits determining sesame seed yield—the number of capsules per plant and the number of seeds per capsule—line number 7 outperformed Dashtestan 2 under full irrigation and was less affected by reduced irrigation or earlier irrigation termination. Conversely, Dashtestan 2 had a superior thousand-seed weight. Overall, line number 7 showed a higher average yield than Dashtestan 2 across irrigation treatments, and did not require irrigation beyond the early capsule- formation stage to reach maximum seed yield, leading to water saving of at least 600 cubic metres per hectare without significant yield reduction. While the maximum irrigation water productivity was similar for both genotypes, Dashtestan 2’s efficiency gains were due to lower water use rather than increased yield, whereas line number 7 achieved both water savings and satisfactory yield (733 kg per hectare) with early irrigation cut-off during capsule setting. Although Dashtestan 2 exhibited up to 1.5% higher seed oil content, line number 7 yielded up to 24% more oil yield than Dashtestan 2.
Conclusion
In conclusion, replacing older sesame cultivars with new lines alongside optimal irrigation management can increase water productivity, reduce water consumption, and prevent yield losses.
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