Introduction
Sesame is a low-expected and low-input crop among oilseed crops, which holds economic significance not only in subsistence agriculture in arid and semi-arid regions of Iran but also in terms of its agronomical characteristics. Shattering tolerant sesame genotypes are crucial for developing sesame cultivation in countries such as Iran. There is a lack of comprehensive information on crop management, including the optimal planting arrangement for imported shattering tolerant sesame genotypes. Therefore, this research was planned and executed to answer the questions regarding the proper planting arrangement of this genotype in two crucial sesame producing provinces, Khuzestan and Fars.
 
Materials and Methods
The experiment was conducted in the Khuzestan (Dezful) and Fars (Darab) Agricultural and Natural Resources Research Center fields during 2019 and 2020. A split-block randomized complete block design with three replications was implemented at each location to investigate the effects of 30, 45, and 60 cm row spacing and 5, 8, 11, and 14 cm plant spacing on yield and yield components of shattering tolerant sesame genotypes. 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 experiment results indicate that reducing the distance between rows and plants increased plant height in both locations. In Darab, increasing the row distance from 30 to 45 cm increased grain yield by 6%, while a further increase in distance to 60 cm decreased grain yield. The highest seed yield of 659 kg per hectare was obtained in Darab using a planting arrangement of 45x5 cm, and the lowest yield was observed with a 21% decrease in yield for the planting arrangement of 60x14 cm. In Dezful, the maximum seed yield of 684 kg per hectare was obtained with a planting arrangement of 45x11 cm. The study results showed that in both locations, the highest grain yields were achieved with a row distance of 45 cm, and the commonly used row distance of 60 cm did not produce the highest yield in either location. Additionally, in Darab, increasing planting density by up to 42 plants per square meter increased seed yield. In Dezful, the maximum seed yield was obtained at a density of 38 plants per square meter.
 
Conclusion
This research suggests that reducing the row distance while maintaining appropriate plant spacing can be a practical approach to achieving high sesame yields. Moreover, increasing plant density can lead to a certain extent of increase in grain yield. However, beyond a certain threshold, as the density further increases, yield decreases due to increased competition among plants. Thus, optimizing planting arrangements, including row and plant spacing, is essential to achieve maximum yields in sesame cultivation.