Introduction
Durum wheat (Triticum turgidum L. var. durum) is an important crop for the human diet grown in many parts of the world predominantly for semolina and resulting pasta production. The presence of genotype × environment interaction (GEI) is a challenge for breeders in evaluating genotypes in multilocational trials. The use of statistical models such as GGE biplot assist breeders in quantifying and understanding the patterns of GEI and in evaluating the performance of genotypes in various environmental conditions. This allows breeders to select stable and adaptable genotypes for a range of environments. One of the important goals of durum wheat breeding programs is to produce high-yielding cultivars that have suitable characteristics for cultivation in different regions of the country. Therefore, the aim of this research was to select promising durum wheat lines in terms of stability and high grain yield by GGE biplot and SHMM models.
Materials and Methods
In this study, 17 promising lines of durum wheat with three check Hana, Aran, Mehregan in five research centers of Kermanshah, Khorramabad, Karaj, Dezful and Fars (Darab) in the form of randomized complete blocks design in 3 replications and in two cropping seasons (2020-2022) were cultivated and compared. The studied genotypes were planted in six lines along 6 m with a line distance of 15 cm. Seed rate was determined by 450 seeds per square meter considering the thousand kernel weight for each genotype. Seeds were sown using an experimental plot planter (Wintersteiger, Ried, Austria). The fertilizer composition was 32 kg ha^-1 nitrogen (twice), and di-ammonium phosphate and potassium sulfate were 100 and 50 kg ha^-1, respectively (before planting). After the removal of perimeter plants, all experimental plots were harvested with an experimental grain harvester (Wintersteiger, Ried, Austria).
Results and Discussion
The results of the combined variance analysis of grain yield showed that the differences between the test environments, genotypes and genotype x environment interaction effect are significant at the 1% level.  The highest grain yield in the first year was observed in Kermanshah station (Ker1) (8441 kg ha^-1) and the lowest seed yield in Khorramabad in the first year (Kho1) (5648 kg ha^-1) and Karaj in the second year (Kar2) (5961 kg ha^-1). GGE biplot analysis determined two durum wheat environmental groups. The first environmental group contained of Kho1, Dar1, Kar1, Kar2 and Dar2 environments, where the recommended genotypes 18, 17, 2 and 19 produced the highest yields. The second environmental group comprised of Kho2, Dez1, Ker2, Dez2 and Ker1 environments, where genotypes 12, 9 and 8 were the best adapted genotypes. Biplot results showed that genotypes 10, 5, 13, 18 and 16 were more stable than other genotypes, respectively. Comparison of the examined genotypes with the ideal genotype showed that genotypes 18 and 10 are the closest genotypes to the ideal genotype, which in addition to high grain yield, had high yield stability. Dar2 was the closest environment to the ideal environment. The results showed that the classification of environments based on the SHMM model was completely consistent with the GGE biplot model. Based on environmental vector of the biplot, Dar2 and Ker1 had high discriminating ability for the genotypes. Also, Dezful in the first and second year (Dez1 and Dez2), Karaj in the second year (Kar2) and Kermanshah in the second year (Ker2) showed low discriminating ability for genotypes. The environments that were placed in the same group were close to each other in terms of genotype x environment interaction values. Based on the SHMM model, the environments with the least cross over effects are placed in one group. Accordingly, the placement of Kermanshah and Dezful in the same group indicates the relative similarity of these places. Also, these results were confirmed by the GGE biplot model.
 Conclusion
As a conclusion, GGE biplot identified G10 (DW-99-10) and G18 (DW-99-18) as the superior durum wheat genotypes which that can be released as new commercial cultivars for the temperate and warm regions of Iran.