Effects of parent choices of provitamin A inbred lines on productivity and stability of their corresponding hybrids.

Abstract

Maize is a cereal that is widely utilized as both a food and feed crop globally. In Africa alone, about 900 million people depend on maize as a staple crop. Although maize is very rich in energy, it contains nutritionally inadequate quantities of some micronutrients such as vitamin A. As a result overdependence on maize and maize products results in vitamin A deficiency (VAD). To combat VAD in people who consume maize as a staple, vitamin A content of maize is being enhanced through biofortification. In this study, 84 provitamin A maize hybrids formed by differently combining provitamin A lines and non provitamin A yellow lines were grown across three sites, representing optimal, high density and random heat stress conditions in Zimbabwe. At each of the locations, hybrids were laid out in an alpha (0.1) lattice design with two replications. Analysis of variance results across all three sites showed significant differences (p<0.05) among the genotypes for grain yield (GY), days to anthesis (AD) and plant height (PH) while the hybrid by site interaction (GEI) was significant for grain yield and plant height only. High broad sense heritability (H2 ), genotypic coefficient of variation (GCV %) values and low environmental coefficient of variation (ECV %) values were observed for GY, highlighting the possibility of the application of direct selection in the effective improvement of this trait. Data revealed that, either a 3-way or a 4-way cross between a provitamin A single cross with a yellow inbred line or a single-cross female respectively, produce hybrids that can compete with the available commercial hybrids. Moreover, hybrids from these combinations showed grain yield stability across the test environments. The potential of hybrids from these two combinations is further buttressed by their ability to reach 50% anthesis at least three days earlier than commercial checks, a trait which is valuable for drought stress adaptation. Overall results show that when parents making up a provitamin A hybrid are properly chosen (provitamin A single cross x a yellow inbred line or a yellow single cross), yield potential and stability of provitamin A hybrids can be enhanced