Estimation of Heterosis and Combining Ability in Different Sunflower Genotypes Using Line × Tester Analysis

Abstract

One important oilseed crop that could help with the scarcity of edible oil is the sunflower (Helianthus annuus L.). This study used a Line × Tester mating design to assess sunflower heterosis and combining ability. Twelve F₁ hybrids were created by crossing four elite inbred lines (HZ-6, HZ-7, HZ-8, and HZ-9) with three testers (PBG-1, PBG-2, and PBG-3). In two seasons (fall 2023 and spring 2024), the parents and hybrids were cultivated using a randomized complete block design with three replications. Plant height, number of leaves per plant, leaf area, internodal length, stem diameter, head diameter, seed yield per head, and 100-seed weight were the eight yield-related characteristics for which data were collected. Significant genetic differences between genotypes for every trait were found by analysis of variance. According to line × tester analysis, non-additive (dominant) gene action predominated for the majority of traits, with specific combining ability (SCA) variance exceeding general combining ability (GCA) variance. Strong GCA effects were seen for important traits (e.g. internodal length, head diameter, seed yield) in the parental lines HZ-6 and HZ-9. Combinations like HZ-6 × PBG-3 and HZ-8 × PBG-1 performed better than other hybrids; HZ-6 × PBG-3 was superior in terms of stem diameter and leaf area, while HZ-8 × PBG-1 was superior in terms of plant height and 100-seed weight. Several traits (most notably head diameter and seed yield) showed positive mid-parent and better-parent heterosis, whereas traits such as internode length, stem diameter, and seed weight showed negative heterosis. These findings imply that sunflower breeding can benefit from hybrid vigour. The high-GCA parents and high-SCA hybrids that have been identified provide useful breeding material for creating improved sunflower cultivars that may increase yield and help lessen the edible oil deficit.