Unravelling economic heterosis for nutritional profiles and grain yield in extra-early provitamin a quality protein maize

Abstract

Heterosis is a crucial genetic mechanism for enhancing grain yield and nutritional quality in extra-early
provitamin A (PVA) Quality Protein Maize (QPM). This study investigated the extent of heterosis in grain
yield, tryptophan content, and carotenoid composition among 10 PVA-QPM hybrids. A partial diallel
mating design, excluding reciprocals, generated 45 F₁ hybrids from 10 extra-early PVA-QPM inbred lines.
These hybrids, along with their 10 parental lines and two commercial hybrid checks, were evaluated under
rainfed conditions at the Lower Niger River Basin Authority, Oke-Oyi, Nigeria, over two consecutive years.
Significant economic heterotic effects were observed for grain yield, with values ranging from -4.29% in
TZEIORQ 26 × TZEQI 82 to 19.38% in TZEIORQ 11 × TZEIORQ 24, demonstrating the genetic advantage
of certain hybrids over commercial varieties. The Tryptophan content exhibited notable positive heterosis,
surpassing 50% in the derived hybrids, further validating the effectiveness of QPM breeding initiatives.
Provitamin A and different carotenoids showed significant hybrid vigour, especially marked by substantial
gains in α-carotene (295.65%), β-carotene (46.80%), and β-cryptoxanthin (40.52%). The low standard
error of difference values (0.0044-0.0124) and highly significant critical differences at 5% (0.0087-0.0247)
and 1% (0.0114-0.0319) levels confirmed the statistical reliability of the findings. These results underscore
the potential of hybrid breeding for biofortification, reinforcing its role in addressing vitamin A deficiency.
Further studies are needed to evaluate genotype-by-environment interactions, ensuring the stability and
adaptability of these hybrids in various agroecological regions