پژوهشنامه اصلاح گیاهان زراعی (Nov 2024)
Evaluation of Some Cumin Ecotypes Based on Selection Index of Ideal Genotype
Abstract
Extended Abstract Background: Cumin (Cuminum cyminum L.) is one of the most important and economic medicinal plants from the Apiaceae family with a considerable distribution in different regions of Iran. The cumin plant is one of the most important medicinal plants in Iran, which needs a lower irrigation to complete the growth stages. Therefore, cumin is one of the most valuable plants for cultivation in arid and semiarid regions of the world. The variety of cultivars is considered one of the important factors affecting the performance of plants. Therefore, the accurate and correct identification of the genotypes and landraces is very useful, in addition to being necessary for crop improvement programs of these plants; it is also very effective in preserving genetic reserves. The objectives of this research were to identify the superior cumin ecotypes based on grain yield and some agronomical traits using the selection index of ideal genotype (SIIG) method, classify cumin ecotypes using the cluster analysis method, and determine the most important traits affecting the essential oil yield trait using stepwise regression. Methods: To evaluate cumin ecotypes using the SIIG, an experiment was conducted on 12 cumin ecotypes based on a randomized complete block design with three replications in the 2022-2023 cropping season. The studied ecotypes were collected from Yazd (Ardakan, Abarkouh, Ashkzar, Bafgh, and Khatam), Fars (Shiraz and Abadeh), Isfahan (Isfahan and Semirom), and Kerman (Kerman, Rafsanjan, and Sirjan). Agronomical traits, including plant height, number of branches per plant, number of umbels per plant, number of seeds per umbel, 1000-seed weight (TSW), grain yield, biological yield, harvest index, essential oil percentage, and essential oil yield, were measured in this research. The SIIG method and cluster analysis were used to select superior cumin ecotypes. Results: The results of the analysis of variance (ANOVA) revealed that ecotypes significantly affected all studied traits at the 1% probability level, except for TSW. Mean comparisons showed that the Sirjan ecotype produced the maximum value of grain yield (642.3 kg/ha), followed by Kerman, Khatam, and Ardakan ecotypes (634, 614.2, and 594 kg/ha, respectively). The minimum values of grain yield were seen in Ashkzar (456.3 kg/ha) and Bafgh (467.11 kg/ha) ecotypes. Mean comparisons showed that Sirjan, Khatam, Kerman, and Ardakan ecotypes attained the highest values in the most traits. The minimum values of plant height were recorded in Kerman and Sirjan, and the maximum value belonged to Bafgh and Ashkzar ecotypes. Sirjan, Kerman, Khatam, and Ardakan ecotypes showed the minimum distance from the ideal genotype (di+), the maximum distance from the non-ideal genotype (di-), and the maximum SIIG value (0.937, 0.926, 0.769, and 0.667, respectively); thus, they were introduced as favorable ecotypes. Ashkzar, Bafgh, and Shiraz showed the maximum distance from the ideal genotype (di+), the minimum distance from the non-ideal genotype (di-), and the minimum SIIG value (0.059, 0.094, and 0.166, respectively); hence, they were introduced as the weakest studied ecotypes. Cluster analysis on significant traits in ANOVA based on the Ward method and using Euclidian distance classified the studied ecotypes into three groups. Sirjan, Kerman, Khatam, Abadeh, and Ardakan ecotypes were placed in the first group, Ashkzar, Shiraz, and Bafgh ecotypes in the second group, and Abarkouh, Isfahan, Semirom, and Rafsanjan in the third group. Grain yield and the most studied traits were higher in the first group ecotypes than in the other groups and the whole mean. Ecotypes of the second group produced the least grain yield and the other studied traits, except for the plant height trait. The third group ecotypes showed average values of the studied traits. The result of the distance between centers of groups obtained from cluster analysis showed that the maximum genetic distance was between ecotypes in the first and second groups. Thus, it could be claimed that the cross between ecotypes in the first and second groups probably produces higher heterosis and genetic variation. For stepwise regression, the essential oil yield trait was selected as the dependent variable, and the other studied traits as independent variables. The result of stepwise regression showed that four traits, including the number of umbel per plant, the number of branches per plant, the number of seed per umbel, and essential oil percentage, were entered the stepwise regression model and could explain 99.5% of the variability among the essential oil yield trait. Conclusion: The results of cluster analysis using the studied traits are similar to those of ecotype ranking based on the SIIG method. The present study showed that the SIIG method could properly classify the ecotypes. The result of cluster analysis and the SIIG method showed that Sirjan, Kerman, Khatam, Abadeh, and Ardakan were the best ecotypes, which can be used in breeding programs and the cultivation development of this plant. Ashkzar, Shiraz, and Bafgh were the worst ecotypes according to cluster analysis and SIIG values.
