Genetic factors influencing grain yield and nutritional qualities in early-maturing provitamin A-enrich quality protein maize

Abstract

Provitamin A quality protein maize (PVA-QPM) is crucial for preventing vitamin A deficiency and malnutrition, widespread public health challenges a public health issue affecting millions, especially children and pregnant women in developing countries. Knowledge of the relationships between maize grain yield, carotenoid levels and quality protein, with their underlying genetic factors, is necessary for developing successful selection strategies for better maize cultivars. The study evaluated the genetic associations and factors optimizing grain yield, carotenoid profiles, and protein quality among newly developed early-maturing, high-performing PVA-QPM inbred lines. Two growing of testing were conducted on ten early PVA-QPM inbreds and two commercial maize hybrid controls under rainfed conditions at the Lower Niger River Basin Development Authority in Ilorin. All nutritional traits and grain yield differed significantly in the PVA-QPM inbreds and commercial hybrids. The PVA-QPM inbreds exhibited higher carotenoid levels than the commercial hybrids, with increases of 4 % for β-carotene and 7 % for β-cryptoxanthin. Despite a 12.9 % lower grain yield (5.73 t.ha⁻¹) compared to the hybrids (6.59 t.ha⁻¹), the nutritional benefits of the inbreds outweigh the yield reduction. There were strong positive genetic correlations between grain yield and most nutritional traits except for a negative genetic correlation between zein and crude protein, lysine and tryptophan, and lysine and tryptophan. Negative associations were also observed phenotypically between grain yield and lutein, as well as between yield and the lysine-to-tryptophan ratio. Path coefficient analysis indicated that grain yield and nutritional traits are directly interrelated through genetic relationships. The genetic linkages between yield and nutritional quality observed in PVA-QPM are considerable in informing breeding strategies for enhancing nutrient contents toward ameliorating chronic malnutrition and global food insecurity in maize-dependent regions.