An Evaluation of Kernel Zinc in Hybrids of Elite Quality Protein Maize (QPM) and Non-QPM Inbred Lines Adapted to the Tropics Based on a Mating Design

Edna K Mageto,Thanda Dhliwayo,Juan Burgueño,Arnel R Hallauer,Félix San Vicente,Natalia Palacios-Rojas,Michael Lee

doi:10.3390/agronomy10050695

Abstract

Genetic improvement of maize with elevated levels of zinc (Zn) can reduce Zn deficiency among populations who rely on maize as a staple. Inbred lines of quality protein maize (QPM) and non-QPM with elevated Zn levels in the kernel have been identified. However, information about the optimal strategy to utilize the germplasm in breeding for high-Zn concentration is lacking. As a preliminary step, this study was conducted to ascertain the potential of QPM, non-QPM, or a combination of QPM and non-QPM hybrids for attaining desirable Zn concentration. Twenty elite inbreds, 10 QPM and 10 non-QPM, were crossed according to a modified mating design to generate hybrids, which were evaluated in four environments in Mexico during 2015 and 2016 in order to evaluate their merits as parents of hybrids. The highest mean values of Zn were observed when high-Zn QPM lines were crossed with high-Zn non-QPM lines. Hybrids with high Zn and grain yield were identified. General combining ability (GCA) effects for Zn concentration were more preponderant than specific combining ability (SCA) effects, suggesting the importance of additive gene action for the inheritance of Zn.

Highlights

Micronutrient deficiency, resulting from inadequate intake of essential minerals such as zinc (Zn), is an increasingly serious food-related health problem [1]
Ten quality protein maize (QPM) and 10 non-QPM inbred lines adapted to tropical and sub-tropical environments were selected for this study (Table 1)
The general categories of the inbreds’ phenotype, groups A–D, may provide some useful information for developing hybrids with increased Zn content, more reliable and relevant results can be obtained by evaluating the inbreds in hybrid combinations

Summary

Introduction

Micronutrient deficiency, resulting from inadequate intake of essential minerals such as zinc (Zn), is an increasingly serious food-related health problem [1]. 20% of the world’s population suffers from Zn deficiency, with the highest risks for young children and pregnant women in sub-Saharan Africa and South Asia [2]. Development of Zn-enriched staple crops through breeding may complement those options [5,6,7]. Maize is one of the major crops grown and consumed in regions where Zn deficiency is prevalent [8,9,10]. In sub-Saharan Africa, 80% of the maize is consumed directly as food, providing at least 30% of the total calories [10,11,12]. Maize improvement programs have primarily focused on developing high-yielding varieties able to tolerate various biotic and abiotic

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