fa تنوع ‍ژنتیکی و روابط بین برخی صفات زراعی و اجزای عملکرد دانه در جمعیت‌های F2 گلرنگ عمومى General پژوهشي Research <div style="text-align: justify;">هدف از این پژوهش، بررسی میزان تنوع ژنتیکی و تعیین روابط بین برخی صفات زراعی و اجزای عملکرد دانه در جمعیت‌های F2 گیاه گلرنگ بود تا از این اطلاعات در برنامه‌های به‌نژادی و بهبود عملکرد دانه استفاده شود. برای این منظور، ۹ جمعیت F₂ حاصل از تلاقی ژنوتیپ‌های متفاوت به همراه ۷ والد آن‌ها (شامل یک ژنوتیپ خارجی و سایر ژنوتیپ‌های بومی ایران) در قالب طرح بلوک‌های کامل تصادفی با سه تکرار در مزرعه تحقیقاتی دانشگاه صنعتی اصفهان کشت و ارزیابی شدند. صفات فنولوژیک (تعداد روز تا شروع گلدهی، ۵۰ درصد گلدهی و رسیدگی)، صفات مورفولوژیک (ارتفاع بوته، تعداد طبق در بوته و قطر طبق) و صفات عملکردی (تعداد دانه در طبق، وزن صد دانه، عملکرد دانه در بوته و در واحد سطح) اندازه‌گیری شدند. نتایج نشان داد که تنوع ژنتیکی معنی‌داری برای اغلب صفات وجود دارد که بیانگر پتانسیل بالای این جمعیت‌ها برای انتخاب در برنامه‌های اصلاحی است. ضرایب تغییرات ژنوتیپی بالا مربوط به تعداد دانه در طبق (13/6 درصد) و وزن دانه در طبق (11/6 درصد) بود، که وراثت‌پذیری عمومی بالایی نیز به ترتیب برابر با 82/5 و 71/2 درصد نشان دادند. ضرایب همبستگی و تجزیه رگرسیون مشخص کردند که صفات تعداد طبق در بوته و تعداد دانه در طبق، بیشترین اثر مستقیم و همبستگی مثبت و معنی‌دار با عملکرد دانه داشته و در مجموع ۷۹ درصد از تغییرات عملکرد دانه در واحد سطح را تبیین نمودند، درحالی که وزن صد دانه تأثیر اندکی داشت. در بین تلاقی-های مورد بررسی، بیشترین عملکرد دانه و درصد روغن در تلاقی ها مربوط به تلاقی 5 ( &nbsp;(IUTc129 &times;IUTE1449با 2364 گیلوگرم دانه در هکتار و 24/7 درصد روغن و در بین والدها مربوط به والد 2) (IUTKh211 با 2642 گیلوگرم دانه در هکتار و 25/8 درصد روغن بود. به‌طور کلی، نتایج نشان می‌دهد که تمرکز بر بهبود صفاتی نظیر تعداد طبق در بوته و تعداد دانه در طبق می‌تواند به‌عنوان راهبردی مؤثر برای ارتقای عملکرد دانه در برنامه‌های اصلاحی گلرنگ به‌کار رود.</div> <div style="text-align: justify;">Extended Abstract:<br> Introduction: Safflower is an important oilseed crop with considerable potential for cultivation in arid and semi-arid regions due to its tolerance to drought and adaptability to marginal soils. Improvement of seed yield as the most important breeding objective in safflower, requires to investigate the genetic diversity and interrelationships among yield-contributing traits. Identifying the key traits associated with seed yield and understanding their direct and indirect effects is crucial for increasing the efficiency of selection in breeding programs, particularly in segregating generations such as F2 populations. The present study aimed to evaluate genetic variability and investigate phenotypic correlations, as well as the direct and indirect effects of several agronomic and yield-related traits on seed yield in F2 safflower populations.&nbsp;<br> <br> Materials and methods: In this study, several F2 populations derived from the crosses between diverse safflower genotypes were used. The genotypes were evaluated in a randomized complete block design (RCBD) with three replications. The data were subjected to analysis of variance to determine the presence of genetic variability. Phenotypic correlation coefficients among the traits were calculated to explore their interrelationships. Stepwise multiple regression analysis was performed to identify the most important yield components contributing to seed yield per unit area. Furthermore, path coefficient analysis was conducted to partition the correlation coefficients into direct and indirect effects for better understanding of the causal relationships among the traits.<br> <br> Results: Highly significant differences were observed among the F2 populations for most of the traits, indicating substantial genetic variability. This wide variation suggests that these populations harbor valuable genetic resources that can be used in selection and breeding programs to improve seed yield. Phenotypic correlation coefficients revealed strong positive and significant correlations between days to flowering, days to 50% flowering, and days to maturity, indicating that genotypes with late flowering tended to have longer growth duration. Plant height exhibited a positive and significant correlation with days to 50% flowering, days to maturity, number of capitula per plant, capitulum diameter, and number of seeds per capitulum, seed weight per capitulum, seed yield per plant, and seed yield per unit area. These results suggest that taller plants with greater vegetative growth can support more reproductive structures and produce higher seed yield. The number of capitula per plant showed a very high positive correlation with capitulum diameter, number of seeds per capitulum, and seed weight per capitulum, as well as with seed yield per plant and seed yield per unit area. Among these traits, the number of capitula per plant had the highest correlation with seed yield, highlighting its importance as an important seed yield component. In contrast, 100-seed weight showed weak and non-&nbsp;significant correlation with seed yield. Generally, cross IUTc129*IUTE1449 (with 2364 kg/ha seed yield and 24.7% seed oil content) among the crosses, and the parental line IUTKh211 (with 2642 kg/ha seed yield and 25.8% seed oil content) among the parental genotypes had the highest seed yield and seed oil percentage, highlighting their superior performance relative to the other genotypes. Stepwise regression identified the number of capitula per plant as the first variable to enter the model, explaining 69% of the variation for seed yield per unit area. The addition of the number of seeds per capitulum increased the efficiency of the model to 78%, and then including 100-seed weight raised the total R&sup2; to 79%. These results emphasize the primary role of the number of capitula per plant in determining seed yield and its superiority over number of seeds per capitulum and 100-seed weight as the other seed yield components.<br> Path analysis results supported the findings of correlation and regression analyses. The number of capitula per plant had the highest positive direct effect (0.67) on seed yield per unit area, followed by the number of seeds per capitulum (0.37). In contrast, 100-seed weight had the lowest direct effect (0.13) and negligible indirect effects on seed yield which was in agreement with its low correlation. These findings collectively demonstrate that the association between the number of capitula per plant and seed yield is mainly due to its strong direct effect rather than its indirect effects.&nbsp;<br> <br> Discussion: The strong positive relationship between the numbers of capitula per plant, the number of seeds per capitulum, and seed yield suggest that selection for these traits can be an efficient strategy to enhance seed yield in safflower. The observed genetic variation among the F2 populations provides an opportunity to select superior genotypes with high numbers of capitula and seeds per capitulum and acceptable agronomic characteristics.<br> The weak association between 100-seed weight and seed yield suggests that this trait is less important for yield improvement in the studied populations. Focusing selection pressure on 100-seed weight might not effectively increase seed yield and could even slow the breeding progress. Instead, improving the number of seeds per plant appears to be a more promising approach.<br> <br> Conclusion: This study demonstrated substantial genetic variation among the F2 populations for morpho-phenological and yield-related traits, which can be exploited for genetic improvement. The results also identified that the number of capitula per plant and the number of seeds per capitulum as the most important traits with direct effects on seed yield, whereas 100-seed weight had the least contribution. Therefore, these yield components can be considered as the reliable selection indices for improving seed yield and developing high-yielding cultivars. The findings of this research provide a valuable information for designing the effective breeding strategies to improve seed yield and its stability in safflower under various environmental conditions.</div> روابط صفات, روغن دانه, عملکرد, جمعیت های در حال تفرق. Traits relationships, Oil content, Grain yield, Segregating populations. 101 120 http://jcpp.iut.ac.ir/browse.php?a_code=A-10-2173-5&slc_lang=fa&sid=1 Ghodratollah Saeidi قدرت اله سعیدی gsaeidi@iut.ac.ir Yes Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan, Iran. گروه تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه صنعتی اصفهان، اصفهان، ایران. Seyed Hosein Ahmadi Moosavi سیدحسین احمدی موسوی hosein.ahmadi2811@gmail.com No Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan, Iran.،Department of Agronomy and Plant Breeding, College of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran گروه تولید و ژنتیک گیاهی، دانشکده کشاورزی، دانشگاه صنعتی اصفهان، اصفهان، ایران، گروه ژنتیک و به نژادی گیاهی، دانشکده کشاورزی، دانشگاه شهید باهنر کرمان، کرمان، ایران Zahra Alizadeh زهرا علیزاده zahra298051@yahoo.com No Department of Agronomy and Plant Breeding, College of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran. گروه ژنتیک و به نژادی گیاهی، دانشکده کشاورزی، دانشگاه شهید باهنر کرمان، کرمان، ایران.