Gains in Maize Genetic Improvement in Eastern and Southern Africa: II. CIMMYT Open‐Pollinated Variety Breeding Pipeline

Masuka, Benhilda; Magorokosho, Cosmos; Olsen, Mike; Atlin, G. N.; Bänziger, Marianne; Pixley, K.V.; Vivek, B.; Labuschagne, Maryke; Matemba-Mutasa, Rumbidzai; Burgueño, Juan; MacRobert, John; Prasanna, B. M.; Das, Bish; Makumbi, Dan; Tarekegne, Amsal; Crossa, José; Zaman-Allah, Mainassara; Biljon, Angeline van; Cairns, Jill E.

doi:10.2135/cropsci2016.05.0408

Cited by 66 publications

(78 citation statements)

References 27 publications

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“…For tropical open-pollinated maize varieties, realized genetic gains reached 0.109 ton ha −1 yr −1 in the early maturity group, and 0.079 ton ha −1 yr −1 in the intermediate-to-late group (Masuka et al 2017b). Therefore, the genetic gains from the RCGS observed in the MPPs used in this study (0.100 ton ha −1 yr −1 ) are at the same or higher level than those observed in other studies under phenotypic selection but with a shorter breeding cycle.…”

Section: Discussionmentioning

confidence: 99%

Rapid Cycling Genomic Selection in a Multiparental Tropical Maize Population

Zhang

Pérez‐Rodríguez

Burgueño

et al. 2017

G3 Genes|Genomes|Genetics

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Genomic selection (GS) increases genetic gain by reducing the length of the selection cycle, as has been exemplified in maize using rapid cycling recombination of biparental populations. However, no results of GS applied to maize multi-parental populations have been reported so far. This study is the first to show realized genetic gains of rapid cycling genomic selection (RCGS) for four recombination cycles in a multi-parental tropical maize population. Eighteen elite tropical maize lines were intercrossed twice, and self-pollinated once, to form the cycle 0 (C0) training population. A total of 1000 ear-to-row C0 families was genotyped with 955,690 genotyping-by-sequencing SNP markers; their testcrosses were phenotyped at four optimal locations in Mexico to form the training population. Individuals from families with the best plant types, maturity, and grain yield were selected and intermated to form RCGS cycle 1 (C1). Predictions of the genotyped individuals forming cycle C1 were made, and the best predicted grain yielders were selected as parents of C2; this was repeated for more cycles (C2, C3, and C4), thereby achieving two cycles per year. Multi-environment trials of individuals from populations C0, C1, C2, C3, and C4, together with four benchmark checks were evaluated at two locations in Mexico. Results indicated that realized grain yield from C1 to C4 reached 0.225 ton ha−1 per cycle, which is equivalent to 0.100 ton ha−1 yr−1 over a 4.5-yr breeding period from the initial cross to the last cycle. Compared with the original 18 parents used to form cycle 0 (C0), genetic diversity narrowed only slightly during the last GS cycles (C3 and C4). Results indicate that, in tropical maize multi-parental breeding populations, RCGS can be an effective breeding strategy for simultaneously conserving genetic diversity and achieving high genetic gains in a short period of time.

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Section: Discussionmentioning

confidence: 99%

Rapid Cycling Genomic Selection in a Multiparental Tropical Maize Population

Zhang

Pérez‐Rodríguez

Burgueño

et al. 2017

G3 Genes|Genomes|Genetics

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“…Using this simultaneous selection approach, Bänziger et al (2006) developed hybrids that have shown a consistent yield advantage over private seed company hybrid checks for all testing environments. Masuka et al (2017aMasuka et al ( , 2017b evaluated genetic gains in the CIMMYT ESA maize hybrid and OPV breeding programs during the period 2000 to 2010. Hybrid gains in grain yield under optimal, managed drought, random drought, low N, and maize streak virus infested conditions were estimated at 1.4, 0.85, 0.85, 0.62, and 2.2% per season, respectively.…”

Section: Core Ideasmentioning

confidence: 99%

On‐Farm Yield Gains with Stress‐Tolerant Maize in Eastern and Southern Africa

Setimela¹,

Magorokosho²,

Lunduka³

et al. 2017

Agronomy Journal

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Core Ideas These selected varieties were compared with the best commercial check varieties on‐farm across 94 locations in eastern and southern Africa in a randomized complete block design with three replications for two seasons. The new drought tolerant hybrids showed a yield advantage over the commercial check varieties both in the early and medium‐late maturing categories by 4 to 19%. Among the CIMMYT hybrids, CZH0616 showed wide adaptation under stress and non‐stress conditions, making it an ideal genotype for smallholders’ farmers. Under farmers’ fields CZH0616, CZH0837, CZH0935, and CZH0928 were high yielding and stable across locations in eight countries that represent major maize production environments in eastern and southern Africa. Maize (Zea mays L.) is the most important staple food in eastern and southern Africa (ESA) with human maize consumption averaging 91 kg capita−1 yr−1. Current maize yield averages 1.2 t ha−1 and is barely sufficient for the region’s requirements due to drought and low N stresses. The objective of this study was to compare new drought tolerant (DT) maize hybrids and open pollinated varieties (OPVs) against the best commercial varieties in ESA under farmer management conditions and to validate on‐station results. Maize varieties were simultaneously selected on‐station in four types of environments across 44 locations in ESA during the 2008/2009 and 2009/2010 seasons. During the 2010/2011 and 2011/2012 seasons, 20 promising DT maize hybrids and OPVs were selected from the on‐station based on their mean grain yield and stability. These selected varieties were compared with the best commercial check varieties on‐farm across 80 locations in ESA in a randomized complete block design for two seasons. The genotype + genotype × environment comparison biplot showed variety CZH0616 together with other new DT hybrids to be stable and high yielding across 44 locations on‐station in the ESA region compared to the commonly grown checks such as SC513. The new DT hybrids showed a yield advantage over the commercial check varieties both in the early and medium‐late maturing categories by 4 to 19%, and the gains were bigger under stress conditions. Under farmers’ fields CZH0616, CZH0837, CZH0935, and CZH0928 were high yielding and stable across locations.

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“…Much higher yield gains of 1.7% yr −1 were reported by Tollenaar (1989) for outstanding maize hybrids developed between the late 1950s and late 1980s and evaluated under drought conditions in Canada. For example, Masuka et al (2017b) demonstrated annual gains in grain yield of 0.029, 0.085, 0.11, and 0.193 Mg ha −1 for early-maturing open-pollinated varieties (OPVs) under natural drought, low N, optimal conditions, and infestation of the Maize streak virus (MSV), respectively, in Eastern and Southern Africa (ESA). For example, Masuka et al (2017b) demonstrated annual gains in grain yield of 0.029, 0.085, 0.11, and 0.193 Mg ha −1 for early-maturing open-pollinated varieties (OPVs) under natural drought, low N, optimal conditions, and infestation of the Maize streak virus (MSV), respectively, in Eastern and Southern Africa (ESA).…”

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confidence: 99%

“…However, only a few reports are available on yield gains for tropical maize evaluated under drought stress. Genetic gains under random drought, low-N, rainfed, and MSV-infested conditions for the intermediate-late-maturing cultivars were reported to be 0.042, 0.053, 0.079, and 0.109 Mg ha −1 yr −1 , respectively (Masuka et al, 2017b). Genetic gains under random drought, low-N, rainfed, and MSV-infested conditions for the intermediate-late-maturing cultivars were reported to be 0.042, 0.053, 0.079, and 0.109 Mg ha −1 yr −1 , respectively (Masuka et al, 2017b).…”

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confidence: 99%

Gains in Grain Yield of Extra‐Early Maize during Three Breeding Periods under Drought and Rainfed Conditions

et al. 2018

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2399 RESEARCH M aize (Zea mays L.) is a major staple crop in West and Central Africa (WCA). The development and commercialization of extra-early maize that matures in 80 to 85 d have made it possible for maize to spread into the savannas of WCA. This has resulted in the expansion of the crop and rapid replacement of the traditional crops, including the indigenous sorghum [Sorghum bicolor (L.) Moench] and pearl millet [Pennisetum glaucum (L.) R.Br.], particularly in the savannas of WCA. This is attributable to the fact that extra-early maize cultivars respond better to application of fertilizer, have a shorter growing cycle, and are ready for harvest much earlier than the indigenous sorghum and millet crops. In addition, as a result of the dry spell usually experienced from November of each year to March of the following year, early and extra-early crops are preferred to reduce the hunger gap in July of each year ABSTRACT Drought is a key maize (Zea mays L.

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Gains in Maize Genetic Improvement in Eastern and Southern Africa: II. CIMMYT Open‐Pollinated Variety Breeding Pipeline

Cited by 66 publications

References 27 publications

Rapid Cycling Genomic Selection in a Multiparental Tropical Maize Population

Rapid Cycling Genomic Selection in a Multiparental Tropical Maize Population

On‐Farm Yield Gains with Stress‐Tolerant Maize in Eastern and Southern Africa

Gains in Grain Yield of Extra‐Early Maize during Three Breeding Periods under Drought and Rainfed Conditions

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