Analysis of variance
The combined analysis of variance results for the seed yields of common bean genotypes in two different locations in 2019 (Bayburt) and 2021 (Kahramanmaras) in summer season are presented in Table 1. According to the ANOVA results, statistically significant differences were found for genotypes (G) (P=0.0122), environments (E) (P=0.0005) and genotype x environment (GxE) interaction (P=0.0053) in terms of seed yield. The significance of the GxE interaction indicates that the studied common bean genotypes responded differently to different environmental conditions and this situation needs to be examined in more detail with stability analyses.
Mean performances and environmental effects
The average seed yields of the seven common bean genotypes in Bayburt and Kahramanmaras locations and their overall averages are given in Table 2. Significant yield differences were observed between locations; the overall average yield of the Bayburt location (123.98 kg/da) was found to be higher than the overall average yield of the Kahramanmaras location (93.94 kg/da).
There were also clear yield differences among genotypes. In the Bayburt location, the Suludere genotype (154.67 kg/da) gave the highest yield, while the Alaciftci genotype (93.37 kg/da) provided the lowest yield. In the Kahramanmaras location, Mollakoy (132.32 kg/da) and Aydintepe (127.68 kg/da) genotypes exhibited the highest yields and the lowest yield was recorded for the Suludere genotype (55.42 kg/da). Looking at the overall averages, Mollakoy (139.69 kg/da) emerged as the genotype with the highest average yield, followed by Aydintepe (123.12 kg/da) and Yukarikirzi (117.16 kg/da). The lowest overall average yield belonged to the Mispir genotype (86.71 kg/da).
GGE biplot analysis
The graph obtained from the GGE Biplot analysis applied to the seed yield data of common bean genotypes is presented in Fig 1. The first two principal components (PC1 and PC2) explained 100% of the total G+GE variation (PC1: 57.16%, PC2: 42.84%). This indicates that the biplot graph fully represents the variation in the data.
The following interpretations can be made from the GGE Biplot graph (Fig 1):
“Which-Won-Where” pattern
Environments (Bayburt and Kahramanmaras) are located in different sectors on the biplot. The Suludere genotype is located at the apex of the sector where the Bayburt environment vector is found, indicating it is the highest-yielding genotype in this environment. Mollakoy and Aydintepe genotypes are located in the sector where the Kahramanmaras environment vector is found, showing the best performance in this environment. Other genotypes were not among the highest-yielding genotypes in these two locations.
Genotype performance and stability
The average environment coordinate (AEC) axis (the horizontal axis of the biplot) shows the average yield performance of the genotypes. Mollakoy, having the furthest projection on the AEC axis, can be considered one of the genotypes with the highest average yield. The vertical line perpendicular to the AEC axis represents stability; genotypes close to this line are considered more stable (
Yan and Kang, 2003). Yukarikirzi genotype is positioned relatively close to the AEC axis, suggesting it exhibits a more stable performance compared to other genotypes. The Suludere genotype, on the other hand, is located quite far from the AEC axis and close to the Bayburt vector, showing strong specific adaptation to this environment but low overall stability.
Evaluation of environments
The angle between the Bayburt and Kahramanmaras environment vectors is greater than 90 degrees, indicating a negative correlation or a strong “crossover” GxE interaction between the two environments (
Yan and Tinker, 2006). That is, genotypes performing well in one environment may not perform similarly in the other. The length of both environment vectors indicates their high power in discriminating genotypes.
Wricke’s ecovalence (W²i)
Wricke’s Ecovalence (W²i) values, which quantitatively estimate the contribution of each genotype to the GxE interaction, are presented in Table 3. According to this parameter, ‘Yukarikirzi’ had the lowest W²i value (99.40), suggesting it was the most stable genotype across the two environments. Conversely, ‘Suludere’ had the highest W²i value (2395.01), indicating the largest contribution to the interaction sum of squares. However, interpreting this high value simply as ‘instability’ can be misleading when viewed in isolation, as a single univariate parameter does not capture the full nature of a genotype’s response. The GGE biplot provides the necessary context, revealing that Suludere’s high W²i value was not due to erratic performance, but rather a strong and positive specific adaptation to the Bayburt environment, where it was the top-performing genotype.
The findings of this study should be interpreted within the context of its primary limitation: the evaluation was conducted in only two locations and in different years. Therefore, this work does not represent a comprehensive GxE interaction analysis but rather a preliminary study aimed at assessing genotype adaptation to two distinctly contrasting agro-ecologies. The choice of Bayburt (cool, high-altitude) and Kahramanmaras (hot, lowland) was deliberate, designed to maximize environmental contrast and observe potential crossover interactions, where the ranking of genotypes changes between environments. The statistically significant GxE interaction found in our ANOVA results confirms that this objective was achieved, as genotypes indeed responded very differently to these two specific conditions.
The GGE biplot analysis proved to be a particularly effective tool for visualizing the strong crossover interaction suggested by the ANOVA
(Yan et al., 2007). This approach is consistent with recent studies in other legumes, where GGE biplot has been successfully used to identify stable and specifically adapted genotypes in crops such as pigeonpea
(Arulselvi et al., 2025). The ‘which-won-where’ pattern clearly showed that different genotypes were superior in each contrasting environment: ‘Suludere’ was the highest-yielding genotype in the cool climate of Bayburt, while ‘Mollakoy’ and ‘Aydintepe’ excelled in the hotter conditions of Kahramanmaras. This finding is a classic illustration of specific adaptation, which can be highly valuable for targeted breeding (
Ceccarelli, 1996). While a single univariate parameter like Wricke’s Ecovalence (W²i) provides a quantitative stability score, its interpretation is greatly enhanced by the GGE biplot’s visual context. For instance, ‘Suludere’ had the highest W²i value, indicating it was the least stable. However, the biplot clarifies that this is not simply instability, but rather a strong, positive adaptation to Bayburt’s specific conditions. In contrast, ‘Mollakoy’ combined a high average yield with good relative stability, representing the type of broad adaptation that is often a primary goal in breeding programs (
Annicchiarico, 2002). ‘Yukarikirzi’, with the lowest W²i value, confirmed its status as the most stable genotype, striking the balance between acceptable yield and high stability that breeders often seek (
Kang, 1993). These findings-identifying genotypes with broad adaptation (‘Mollakoy’) alongside those with strong specific adaptation (‘Suludere’)-are strongly supported by similar research on common bean in comparable Mediterranean environments. For instance,
Kargiotidou et al., (2019), also using GGE biplot analysis in Greece, similarly identified commercial cultivars with high yield and stability (wide adaptation) while noting that a local landrace was high-yielding but unstable, thus representing a valuable genetic resource for specific adaptation.
The two test environments, Bayburt and Kahramanmaras, discriminated genotypes differently on the GGE Biplot and showed a strong “crossover” G´E interaction between them (angle between vectors >90
o). This is an expected result considering the different growing seasons of the two locations (Bayburt 2019, Kahramanmaras 2021) and the distinct climatic differences detailed above (temperature, precipitation regime). The cooler and later vegetation period of Bayburt may have enabled some genotypes (Suludere, Yukarikirzi) to perform better under these conditions, while the hotter and earlier vegetation period of Kahramanmaras may have been more suitable for genotypes with different adaptation mechanisms, such as Mollakoy and Aydintepe. If there had been a positive correlation between test environments (angle between vectors <90
o), the probability that selection made in one environment would also be valid for the other environment would have increased (
Yan and Tinker, 2006). This strong negative correlation underscores the value of this study not for broad-scale GxE analysis, but for identifying specifically adapted genotypes for these types of contrasting mega-environments (
Gauch and Zobel, 1997).
In conclusion, the combined use of GGE biplot and a stability parameter like Wricke’s Ecovalence proved effective for interpreting genotype performance in this preliminary adaptation trial. While the findings are specific to the environments and years tested, they provide a strong rationale for future research. To validate the potential broad adaptation of ‘Mollakoy’ and the specific adaptation of ‘Suludere’, these genotypes should be tested across a wider range of locations and years, which would allow for a more comprehensive understanding of GxE interactions in Turkish common bean breeding programs.