Combining ability of extra‐early biofortified maize inbreds underStrigainfestation and low soil nitrogen

Abstract

Striga hermonthica (Del.) Benth parasitism, low soil N, and nutritional deficiencies of normal-endosperm maize (Zea mays L.) threaten maize yield and exacerbate nutritional problems in sub-Sahara Africa (SSA). This study was conducted (a) to evaluate genetic variation among extra-early maturing maize hybrids with provitamin A and quality protein characteristics, (b) to investigate gene action governing the inheritance of Striga resistance, grain yield, low N tolerance, and other measured traits under low-N, high-N, and Striga-infested environments, and (c) to identify hybrids with high yield and stability across environments. One hundred and fifty hybrids developed using North Carolina Design II were evaluated with six checks under low-N, high-N, and Striga-infested environments in Nigeria. Mean squares for hybrids were highly significant (P < .01) for grain yield and other traits across environments. Only general combining ability (GCA) for female and/or male mean squares were significant for measured traits under low N. In addition to significant GCA effects for most traits, specific combining ability was significant (P < .05) for Striga emergence count under Striga infestation, and ear height and ears per plant under high N, indicating that additive and nonadditive genetic effects controlled the inheritance of few traits under Striga and high N, whereas additive genetic effect governed the inheritance of the traits under low N. Hybrids TZEEIORQ 55 × TZEEIORQ 26, TZEEIORQ 49 × TZEEIORQ 75, and TZEEIORQ 52 × TZEEIORQ 43 were high yielding and stable across environments and have potential for improving nutrition and maize yields in SSA. Abbreviations: AEA, average environment axis; ASI, anthesis-silking interval; ATC, average tester coordinate; DA, days to 50% anthesis; DS, days to 50% silking; EASP, ear aspect; EHT, ear height; EPP, ears per plant; ESP1, Striga emergence count at 8 wk after planting; ESP2, Striga emergence count at 10 wk after planting; GCA, general combining ability; GCA f , general combining ability for female effect; GCA m , general combining ability for male effect; GGE, genotype main effect plus genotype x environment interaction;

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

“…The results of the present study agreed with those of other researchers(Ifie All rights reserved. 21 maternal effects for GY under contrasting environments but contradicted the findings ofOyekale et al (2020) who reported significant maternal effects for GY under LN, Striga and HN conditions.The significant GCA-male x Env, GCA-female x Env and SCA x Env interactions for GY under the different management conditions suggested that the combining ability of the parents varied across LN, Striga and HN conditions. The result inferred that the additive and non-additive gene effects interacted with the environments in their expression, which justified the importance of multilocation testing in breeding LN tolerant and Striga resistant/tolerant hybrids.…”

“…While Ertiro et al (2017), Obeng-Bio et al (2019) and Oyekale et al (2020) reported the inheritance of grain yield under LN to be largely influenced by additive gene action, Badu-Apraku et al (2016), Mafouasson et al (2017) and Annor et al (2019) reported prominence of non-additive genes. Under Striga, Badu-Apraku et al (2020) and Oyekale et al (2020) established that additive gene effects played a greater role in the inheritance of grain yield, Striga damage syndrome rating and Striga emergence while Badu-Apraku et al (2016) documented superiority of non-additive gene effects. Maternal effects were reported to influence the inheritance of grain yield and few traits under LN, Striga and HN conditions by Oyekale et al (2020) while Ifie et al (2015) reported non-significant maternal effects under similar growing conditions.…”

“…Under Striga, Badu-Apraku et al (2020) and Oyekale et al (2020) established that additive gene effects played a greater role in the inheritance of grain yield, Striga damage syndrome rating and Striga emergence while Badu-Apraku et al (2016) documented superiority of non-additive gene effects. Maternal effects were reported to influence the inheritance of grain yield and few traits under LN, Striga and HN conditions by Oyekale et al (2020) while Ifie et al (2015) reported non-significant maternal effects under similar growing conditions. The inconsistencies in the literature indicate that the expression of genes for LN tolerance and Striga resistance/tolerance are germplasm dependent, making it prudent to determine the gene action for the newly developed QPM yellow and orange inbred lines.…”

“…(2020) and Oyekale et al. (2020) established that additive gene effects played a greater role in the inheritance of grain yield, Striga damage syndrome rating, and Striga emergence, whereas Badu‐Apraku et al. (2016) documented superiority of nonadditive gene effects.…”

Development of Extra-Early Provitamin A Quality Protein Maize Inbreds with Resistance/Tolerance to Striga hermonthica and Soil Nitrogen Stress

“…The total potassium (K), phosphorus (P) and nitrogen (N) contents of the soils were determined by Kjeldahl digestion and colorimetric method [41]. The soil analyses at Ile-Ife and Mokwa used in this study are the same as reported by [42]. Following the soil test, the total N available in the high-and low-N plots were augmented with urea to 90 and 30 kg N ha −1 , respectively.…”