Introduction: Despite the desirable nutritional profile of sesame and the appropriate adaptation of this crop to the country's climatic conditions, the cultivation of this crop is not given that attention compared to other oilseeds. Because of its highly variable seed yield further agronomic research and management strategies are critical to improve sesame quantitative and qualitative yield. Planting arrangements and planting density are the most important agronomic practices that need attention. In addition, like many other sesame-producing countries, Iran has numerous local sesame populations adapted to their respective production regions' climatic and soil conditions. However, these populations are not suitable for large-scale cultivation and mechanized farming. In 2016, a sesame genotype resistant to seed shattering was imported into the Iran suggesting its potential contribution to sesame cultivation programs in the country. Due to the lack of comprehensive information to answer the questions rose regarding the planting arrangement and suitable planting density of the imported shattering tolerant sesame genotypes, this research was planned and executed.
Materials and Methods: Field experiments were conducted in Sistan and Baluchistan (Zabol) located at 61° 41' longitude and 30° 54' latitude, with an elevation of 492 meters above sea level and Kerman (Jiroft) located at 57° 51' longitude and 28° 32' latitude, with an elevation of 1100 meters above sea level provinces in 2021 and 2022. In this study, the effects of row spacing (30, 45, and 60 cm) and plant spacing (5, 8, 11, and 14 cm) were investigated on growth characteristics (plant height, number of sub-branches), seed yield, yield components, oil percentage and oil yield of a shattering tolerant sesame genotype. In each location, the experimental design was a randomized complete block design arranged in split blocks (strips) with three replications. The collected data were analyzed using SAS software (version 9.4), and Bartlett's test confirmed homogeneity in the variance of all studied traits. The mean values for both years were presented since the data were consistent. It is important to note that the data from each region were analyzed separately due to inconsistent variances between regions. Statistical significance was determined using an F-test, and protected LSD was used to separate the main effects when necessary. Furthermore, significant interaction effects were separated using the slicing method.
Results and Discussion: The results showed that seed yield was not affected by experimental treatments in the Zabol region. In the Jiroft region, the results indicated that in all the treatments of plant spacing, cultivation in row spacing of 30 cm was significantly superior compared to other row spacing (45 and 60 cm). The maximum seed yield in this area (1430 kg ha^-1) was obtained from the planting arrangement of 14 × 30 cm, which was 10 and 29% higher, compared to the same treatment in the row spacing of 45 and 60 cm, respectively. Also, the results indicate that the seed yield in Zabol did not show a specific reaction to the increase or decrease in density. In contrast, seed yield in the Jiraft region increased up to the density threshold of 33 plants per square meter, and after that, seed yield was reduced with a further increase in planting density.
Conclusion: This research showed that the yield potential of the imported shattering tolerant sesame genotype in the Zabol region was lower than the average yield in this region. Therefore cultivation of this genotype in the Zabol region is not suitable. In the Jiroft region, the maximum seed yield obtained from this genotype was up to 300 kg ha^-1, higher than the average yield of sesame in the Jiroft region. Therefore, the shattering tolerant genotype, especially in the 30 × 14 cm cultivation arrangement, has a good potential for cultivation in the Jiroft region.