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چکیده
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Genetic improvement of black cumin (Nigella sativa L.), particularly with regard to yield performance, is needed for enhancing its productivity in semi-arid environments. This study aimed to assess the morphological diversity among 27 black cumin genotypes collected from various regions of Iran and to explore their genetic potential using the genotype × trait biplot model for trait associations. A total of 14 morphological traits were measured, including plant height (PH), length of internodes (LI), length of flowering stem (LFS), number of internodes of the main stem (IMS), chlorophyll content (CC), follicle width (FW), follicle length (FL), number of seeds per follicle (NSF), seed length (SL), seed width (SW), number of follicles per plant (NFP), capsule weight (CW), thousand seed weight (TSW) and seed yield (SY). Based on biplot analysis, 62 and 18% of total variation was explained by the first and second components, respectively. Genotypes G24 and G25 emerged as the most promising for high yield and favorable trait associations, being closest to the ideal genotype position. Traits such as FL, CW, LFS, and NSF were identified as the most discriminative traits for selecting high-yielding genotypes. Conversely, traits like TSW showed little correlation with SY and did not significantly influence yield performance in this study. The results also highlighted the importance of considering genotype × trait interactions in breeding programs, as these interactions significantly affect the selection of superior genotypes. The biplot analysis helped identify the best genotypes based on multiple traits, facilitating a more informed selection process for breeding purposes. Genotypes G24 (Mashhad-II) and G25 (Marivan) were recommended for further testing in multienvironmental trials to assess their adaptability and yield stability.
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