Plant Productions

Plant Productions

Genetic diversity assessment and cluster analysis of safflower (Carthamus tinctorius L.) germplasm for improving yield-related traits and oil quality

Document Type : Research Paper - Plant Breeding

Authors
Parisa Sheykholeslami 1
Jalal Saba 1
Mohammadreza Nazari 2
Afshin Tavakoli Zaniani 1
Kamran Afsahi 1
1 Department of Plant Production and Genetics, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
2 Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
10.22055/ppd.2025.50367.2287
Abstract
Introduction
Safflower (Carthamus tinctorius L.), a valuable oilseed crop, has considerable genetic potential for improving seed yield and oil quality through targeted breeding programs. However, its production may be constrained by low yield potential, a relatively long growing season, and limited seed oil content in some genotypes. Therefore, identifying and characterizing genetically diverse germplasm based on agromorphological traits, yield components, and fatty acid composition is essential for selecting promising genotypes and developing improved cultivars with higher productivity and desirable oil quality.

Materials and Methods
In this study, 120 safflower (Carthamus tinctorius L.) genotypes collected from diverse genetic resources worldwide were comprehensively evaluated at the Karaj Seed and Plant Improvement Research Institute using an augmented design with five check cultivars (Goldasht, Golmehr, Parnian, Soffe and Faraman). Agromorphological traits and fatty acid compositions of these genotypes were measured, followed by separate cluster analyses for each trait group, correlation analysis, and boxplot visualization performed using R software.

Results and Discussion
Analysis of variance revealed significant differences among most of the evaluated traits, indicating considerable genetic diversity among the safflower genotypes. Genetic parameter estimates showed that the highest phenotypic and genotypic coefficients of variation were observed for the number of branches per plant (38.4% and 36.9%, respectively) and seed yield (39% and 34.3%, respectively). Except for head diameter (26.3%), all traits exhibited high broad-sense heritability (67.6–98.2%), indicating substantial genetic variation and their potential for utilization in future breeding programs. Independent cluster analyses grouped the genotypes into five distinct clusters based on agromorphological traits and six clusters based on fatty acid composition. Among the agromorphological clusters, cluster II comprised genotypes characterized by high yield and early flowering, with E31, E186, E178, E167, and E37 identified as promising candidates for improving yield and escaping end-of-season stress. Cluster V, distinguished by the highest oil content, included E195, E172, E200, E77, and E180, which combined favorable seed yield with high oil content, representing valuable genetic resources for the simultaneous improvement of these traits. In the fatty acid composition-based clustering, clusters I and II exhibited high oleic acid content, contributing to greater oxidative stability of the oil, whereas clusters III–V were characterized by higher linoleic acid levels, highlighting their nutritional value. Compared with the collected germplasm, commercially released cultivars exhibited lower values for both agromorphological traits and oleic acid content, emphasizing the importance and potential of the newly evaluated genotypes. Boxplot analysis combined with significance testing demonstrated that geographic origin, thorniness, and flower color influenced variation in seed yield, days to flowering initiation, oil content, and fatty acid composition. Further analysis revealed that Pakistani genotypes predominantly exhibited early flowering, Iranian genotypes showed late flowering, and American genotypes had the highest oil content. African and Pakistani genotypes exhibited superior seed yield, whereas thorny genotypes tended to flower earlier, and genotypes with yellow flowers and thorns showed higher oil content. Notably, linoleic acid was found in higher concentrations in the white-flowered lines than in the yellow, orange and red-flowered lines, but the differences were not significant. Conversely, the oleic acid content was lowest in the white-flowered genotypes but the difference was not significant from the other flower colors. Similarly, the stearic acid, palmitic acid, and seed protein content were lowest in the white-flowered genotypes.

Conclusion
The findings of this study highlight the superior potential of the evaluated genotypes relative to the commercially released cultivars, which typically showed lower performance. This underscores the value of this germplasm as a promising resource for breeding programs aimed at the simultaneous improvement of yield and quality traits in safflower. Additionally, characteristics such as geographic origin, flower color, and thorniness can serve as effective phenotypic markers in the preliminary screening of genotypes. Among these, genotypes with yellow flowers and thorns exhibited significantly higher oil content, while genotypes originating from Pakistan showed considerable breeding potential due to their favorable combination of early flowering and high seed yield.
Keywords
Early flowering
Fatty acid composition
Oil content
Qualitative traits
Subjects
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Plant Productions
Volume 49, Issue 3
Summer 2026
Pages 465-484