Genetics of extra‐early‐maturing yellow and orange quality protein maize inbreds and derived hybrids under low soil nitrogen and Striga infestation

Abstract

Ideas 1. General combining ability (GCA) effects were superior over specific combining ability (SCA) effects indicating that additive genes largely controlled grain yield and other traits among the newly developed extra-early quality protein maize inbred lines under low nitrogen, Striga-infested and high nitrogen conditions. 2. Maternal genetic effects influenced plant height under Striga-infested condition which suggested that inbred lines that exhibited significant and positive GCA-female effects for plant height should not be used as female parents to avoid production of tall hybrids that are liable to lodging. 3. Genetic distances were significantly associated with grain yield under low nitrogen, Strigainfested and high nitrogen conditions which implied that inbred lines that had high pairwise genetic distances should be considered for hybrid production to maximize heterosis. This article is protected by copyright. All rights reserved. 2 4. TZEEQI 358 displayed significant and desirable GCA effects for grain yield and other important traits across low nitrogen, Striga-infested and high nitrogen conditions and could be a useful source of valuable alleles for population improvements. 5. TZEEIORQ 58 x TZEEQI 397 exhibited high grain yield and stability across the low nitrogen, Striga-infested and high nitrogen environments and could potentially address the food and nutritional insecurities prevailing in sub-Saharan Africa.

Genetic Analysis of Early White Quality Protein Maize Inbreds and Derived Hybrids under Low-Nitrogen and Combined Drought and Heat Stress Environments

“…Partitioning the QPM hybrids into genetic components, significant GCAm and GCAf mean squares were observed for grain yield and other measured traits under low-nitrogen environments implied that additive gene action was more important in the inheritance of grain yield and other measured traits under low-nitrogen. Similar findings were reported by Ifie et al [30], Annor and Badu-Apraku [31], Obeng-Bio et al [11], and Abu et al [32] on the preponderance of the additive gene action over the non-additive gene action in the inheritance of grain yield under low-nitrogen environments. Contrarily, studies by Makumbi et al [33], and Neolle et al [34] reported non-additive gene action to be more important in the inheritance of grain yield under low-nitrogen environments.…”

“…The inconsistencies in the reports on the relative importance of the additive and non-additive gene action in the inheritance of grain yield and other traits call for the need for further studies to confirm the type of gene action controlling grain yield and other agronomic traits in the newly developed early maize QPM inbred lines in the IITA-MIP. Additionally, several studies have reported the preponderance of additive gene action over non-additive gene action in the inheritance of grain yield under low-nitrogen conditions [12,[30][31][32]. Contrarily, studies by Makumbi et al [33] and Badu-Apraku et al [26] reported that non-additive gene action conditioned the grain yield of maize hybrids under low-nitrogen, while Noelle et al [34] reported that both additive and non-additive genetic action conditioned grain yield when soil nitrogen was low.…”

Genetic diversity and inter-trait relationship of tropical extra-early maturing quality protein maize inbred lines under low soil nitrogen stress

“…Also, the absence of clustering based on LN tolerance or tryptophan content is supported by previous finding of [ 65 , 66 ] who reported that clustering among a set of CIMMYT inbreds and open pollinated varieties was independent of the phenotype or environmental adaptations. The high genetic distances between inbreds from different source populations which caused them to be grouped under different clusters suggested that hybrid crosses between yellow and orange lines from different clusters would produce higher heterosis compared to crosses between only yellow or orange lines within to the same cluster [ 6 ].…”

“…Seed samples of 65 (55 yellow plus 10 orange lines) selected inbred lines were dispatched to the Maize Nutritional Quality and Plant Tissue Analysis Laboratory of CIMMYT, for tryptophan analysis using the calorimetric method [ 24 ]. The 65 inbred lines were selected because they were newly developed lines with high levels of pro-vitamin A and/or lysine and tryptophan contents, and were also of major interest for the combining ability studies [ 6 ]. Tryptophan content of each genotype was estimated from two independent samples.…”

“…Adu et al [ 5 ] reported wide genetic distances among 94 early maturing white and yellow endosperm stress tolerant tropical maize inbred lines suggesting the presence of unique alleles for maize improvement. In another study by Abu et al [ 6 ] significant correlation was observed between genetic distances and grain yield (GY) performance of tropical QPM maize inbred lines under low soil nitrogen (LN), Striga and optimal growing environments. Suwarno et al [ 4 ] also reported correlations between single nucleotide polymorphism (SNP)-based heterotic groupings and high heterosis of selected provitamin A maize inbred lines.…”