Journal of Crop Production and Processing

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Hosseinifard M, Majidi M M, Saeidi G, Mohammadi M. Genetic Analysis and Drought Tolerance Evaluation in Populations Derived from Crosses Between Iranian and Foreign Safflowers. Journal of Crop Production and Processing 2025; 15 (4) :75-97
URL: http://jcpp.iut.ac.ir/article-1-3385-en.html

Extended Abstract
Introduction: Safflower (Carthamus tinctorius L.), a member of the Asteraceae family, is globally cultivated as a multipurpose oilseed crop, prized for its high-quality edible oil (rich in unsaturated fatty acids), industrial applications, and adaptability to marginal environments. Its agronomic significance is particularly pronounced in arid and semi-arid regions, where its intermediate drought tolerance and low water requirements make it a resilient alternative to more sensitive crops. Despite its potential, safflower’s genetic improvement has lagged behind other oilseeds, partly due to limited exploitation of exotic germplasm and insufficient characterization of its genetic architecture under abiotic stresses. In Iran, where water scarcity and soil salinity increasingly threaten agricultural productivity, the narrow genetic base of local safflower cultivars exacerbates vulnerability to climate variability. While traditional breeding has achieved moderate gains in yield and stress tolerance, incorporation of foreign genetic resources (e.g., drought-adapted lines from India, Africa, or the Mediterranean) may reveal new allelic variations. The potential of exotic genetic diversity for improving drought tolerance through crosses with domestic cultivars, as well as gaining a deeper understanding of the genetic control of key traits, has been largely underutilized.  

Materials and Methods: In this study, 64 safflower genotypes, including 45 F2 populations from half-diallel crosses among 10 parents, 10 parental lines, and 9 check varieties, were evaluated at the research farm of the College of Agriculture, Isfahan University of Technology, located in Isfahan, Iran (32º 42′ N, 51º 28′ E, 1624 m above sea level) in 2022. The experiment was laid out as a randomized complete block design with two replicates under two environments: drought stress (90% depletion of available water) and non-stress (50% depletion). Sowing was performed on December 1st, and irrigation was controlled using a TDR moisture meter and related formulas. Traits measured included days to flowering, day to maturity, plant height, number of heads per plant, 1000-grain weight, and grain yield, along with physiological traits like relative water content (RWC) of leaves were measured. Statistical analyses including normality tests, analysis of variance, and estimation of general combining ability (GCA) and specific combining ability (SCA) effects were performed using SAS software; genetic parameters and heritability were estimated accordingly.

Results and Discussion:  Mean comparison revealed significant reductions in the traits such as RWC and grain yield under drought stress. However, the higher genetic diversity among the 45 hybrid populations led to the identification of genotypes with superior yield potential and enhanced stress tolerance indices. Notably, the remarkable stability of 1000-grain weight in certain crosses under stress conditions highlighted their genetic potential for drought-tolerance breeding programs. Genetic analysis of the F₂ generation indicated that most traits exhibited significant GCA variance, emphasizing the role of additive gene effects in their inheritance. However, for traits such as days to flowering, head diameter, 1000-grain weight, and grain yield, significant SCA variance suggested the additional influence of dominance effects. This underscores the potential for heterosis breeding in improving certain traits through hybrid development. A high broad-sense heritability was observed for a number of traits, indicating the feasibility of effective early-generation selection. Parental lines G54, G74, and G40, with the highest stress tolerance index (STI), were identified as drought-tolerant parents. The involvement of G74 in crosses resulted in the lowest percent reduction in yield (PRI) and high GCA, highlighting the critical role of additive genetic factors in controlling yield-related traits under drought stress. Additionally, crosses such as 54×74, 32×74, and 74×71 exhibited high STI and low PRI, making them promising genetic populations for drought-resistance breeding. The cross 86×40 demonstrated the best SCA effects, benefiting from the high GCA of both parents (G40 and G86), leading to superior genetic performance across multiple traits. 
 
Conclusions: The analysis confirmed that combining local and foreign germplasm results in considerable genetic diversity in the new populations, which enhances opportunities for improving drought tolerance and yield stability. Additive and dominance effects play key roles in controlling most of the traits. Crosses like 74×67 along with parents such as G71 are valuable resources for breeding tolerant varieties. Furthermore, crosses such as 54×74, 32×74, and 74×71 showed high STI values and low PRI scores, indicating superior performance and stability under water-limited conditions. Overall, the results indicated that utilizing a diverse parental pool and targeted hybridization can generate high genetic variability, making it possible to develop high-yielding, drought-tolerant safflower cultivars suitable for production in arid regions.