Introduction: Sesame (Sesamum indicum L.) is an important oilseed crop belonging to the Pedaliaceae family with high quality yield, which can be said to have originated in some developing countries in the world due to the need for labor, and high rural harvest. Sesame is an edible plant that contains odorless oil. In addition, it is also a good source of protein and fat for humans and pets.
Crops are grown underwater in dry and semi-arid regions where water pressure is great. Furthermore, it is sensitive to the dry season, mainly in the vegetative stage in all growing districts, and its production potential is low in semi-arid areas due to water stress. Since much of Iran's land is located in arid and semi-arid areas, this has led breeders to enhance water or drought tolerance traits, which is one of the main goals of the program crop improvement. However, genotype × environment interaction poses a major challenge in studying quantitative traits because it reduces yield stability across different environments and also complicates the interpretation of genetic experiments, and makes prediction difficult. A stable genotype has performance that remains constant or little changed regardless of any changes in environmental conditions. Several stability analyzes have been proposed to determine the linear relationship between genotype and environment performance. Among these, Eberhart and Russell (1966) proposed a method in which the environmental index is the average performance of all inputs in an environment. Therefore, further research into sesame's genetic differences and breeding is needed to progress and stabilize its yield under different environments. These findings may be applicable in detecting how sesame genetic resources may be used to develop novel cultivars suited to dry settings or enhance remaining cultivars.
Materials and Methods: In this regard to analyze genotype × environment interaction and determine the grain yield stability of 104 sesame genotypes in the tropics and subtropical climates of Iran, an alpha lattice design with two replications during 2019 in two stations, including Kerman and Jiroft were evaluated under two conditions, normal irrigation, and drought stress at the end of the season (irrigation interruption in 50% of flowering). Then, the univariate statistics of regression coefficient (bi), mean squares of deviation from regression (Sdi2), Shukla’sstability variance (σi2), Wricke’s ecovalence (Wi2), Environmental variance (Si2), determination coefficient values (R2) and coefficient of variability (C.V) were used to evaluate the stability of the grain yield of genotypes.
Results and Discussion: Combined analysis of variance showed that the effects of genotype, environment × genotype and genotype × environment linear on grain yield were significant, suggesting that genotypes differ in response to changes in environment. In order to study the interactions of genotype × environment more precisely and to determine genotypes with stable and high yields, different stability parameters were calculated for each genotype. Calculating stability parameters showed that genotypes G14, G19, G42, G80, G46, G69, G44, and G43 were recognized as genotypes with stable yield and suitable adaptation, respectively.
Conclusion: Different parametric and non-parametric stabilization procedures can be proposed to select drought-tolerant genotypes under different environmental conditions; these procedures can be used to identify the best genotypes under drought conditions. Therefore, yield stability analysis can be used in combination with parametric and non-parametric methods to evaluate and identify drought-tolerant genotypes. In this research, the studied genotypes indicated various environmental responses and proved a high genetic ability to adapt to water-deficient stress conditions. According to the findings of this research, the genotypes Jiroft local cultivar, Dezful local cultivar, TN78-84, SG90154-137, JL18 (82), SG90154-71, TN78-369, and, Halil had the best at adapting to environments with water stress. Therefore, according to the above analysis results, these genotypes can be introduced to low-water areas of Iran.