Assessment of Heritability and Correlation Analysis of Yield and Oil-Related Traits in Different Safflower (Carthamus tinctorius L.) Genotypes

Abstract

Genetic variability and reliable heritability estimates are prerequisites for effective selection in plant breeding. This study assessed heritability and trait correlations for yield and yield-related characters in ten safflower (Carthamus tinctorius L.) genotypes. The experiment was carried out during the Rabi season of 2025–2026 at the Experimental Field, Botanical Garden, Department of Plant Breeding and Genetics, Sindh Agriculture University, Tandojam, Sindh, Pakistan. A Randomized Complete Block Design (RCBD) with three replications was used. Nine yield and yield-related traits were recorded and analyzed. Analysis of variance revealed highly significant (P ≤ 0.01) differences among the genotypes for all studied traits, indicating the presence of substantial genetic variability and considerable potential for genetic improvement through selection. Based on mean performance, genotypes PI-304093 and PI-306956 exhibited superior performance for most of the evaluated traits, suggesting their potential as valuable genetic resources for developing high-yielding safflower cultivars. Correlation analysis showed that most yield-related traits were positively and significantly associated with one another, indicating the possibility of simultaneous improvement through selection. High broad-sense heritability estimates were observed for days to 90% maturity (96.23%), plant height (97.99%), days to 75% flowering (95.09%), biomass per plant (79.97%), seed yield per plant (78.84%), oil content (67.69%), harvest index (62.25%), and capsules per plant (61.93%). These results indicate that direct phenotypic selection can be effective for most traits, and that harvest index may serve as a useful indirect selection criterion for improving seed yield. Genotypes PI-304093 and PI-306956 are recommended as promising parental material for safflower breeding, while multi-location, multi-season trials are suggested to confirm their stability before use in cultivar development.