Combining ability and gene action for grain yield and biofortification traits in pearl millet [Pennisetum glaucum (L.) R. Br.]: Implications for breeding high-yielding nutrient-dense hybrids

Micronutrient malnutrition, particularly iron and zinc deficiency, affects over two billion people globally, with women and children in developing countries being the most vulnerable. Pearl millet [ Pennisetum glaucum (L.) R. Br.], a climate-resilient cereal in arid and semi-arid regions, presents a very good opportunity for biofortification as it has an inherently high micronutrient level and genetic variability. The present investigation aimed to estimate combining ability effects, establish gene action, and identify superior parents and hybrids for the simultaneous improvement of grain yield and biofortification traits. Ten genetically diverse inbred lines were crossed in a half diallel mating design, following Griffing's Method 2, Model 1. The resulting 55 entries (45 F₁ hybrids and 10 parents) were evaluated across two environments in a randomized complete block design with three replicates. The analysis revealed high broad-sense heritability for iron (0.94), zinc (0.90), and protein (0.90) contents. Among parents, RIB-9205 had the highest GCA for iron content (6.65***), RIB-9184 for zinc (3.85***), and protein (0.78***), and RIB-15131 was a balanced multi-trait combiner. RIB-9184 x RIB-15131 showed the best hybrid with the highest multi-trait selection index value of 1.31, which produced good grain yield (18.84 g/plant) with improved iron (46.16 ppm), zinc (38.86 ppm), and protein (11.91%) content. The strong positive correlation between iron and zinc (rg = 0.82**) enables an efficient simultaneous improvement. The results suggest hybrid breeding for yield maximization and population improvement approaches for biofortification traits to develop high-yielding, high-nutrient pearl millet cultivars.