Person:
Semagn, K.

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Semagn
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Semagn, K.

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Now showing 1 - 5 of 5
  • Genetic gains in grain yield through genomic selection in eight bi-parental maize populations under drought stress
    (CSSA, 2015) Beyene, Y.; Semagn, K.; Mugo, S.N.; Tarekegne, A.T.; Babu, R.; Meisel, B.; Sehabiague, P.; Makumbi, D.; Magorokosho, C.; Oikeh, S.O.; Gakunga, J.; Vargas Hernández, M.; Olsen, M.; Prasanna, B.M.; Banziger, M.; Crossa, J.
    Publication
  • The development of drought tolerant maize germplasm in sub-Saharan Africa using marker-assisted recurrent selection and genomic selection
    (CIMMYT, 2016) Beyene, Y.; Semagn, K.; Mugo, S.N.; Meisel, B.; Oikeh, S.O.; Tarekegne, A.T.; Olsen, M.; Prasanna, B.M.; Crossa, J.
    Publication
  • Performance and grain yield stability of maize populations developed using marker-assisted recurrent selection and pedigree selection procedures
    (Springer, 2016) Beyene, Y.; Semagn, K.; Mugo, S.N.; Prasanna, B.M.; Tarekegne, A.T.; Gakunga, J.; Sehabiague, P.; Meisel, B.; Oikeh, S.O.; Olsen, M.; Crossa, J.
    A marker-assisted recurrent selection (MARS) program was undertaken in sub-Saharan Africa to improve grain yield under drought-stress in 10 biparental tropical maize populations. The objectives of the present study were to evaluate the performance of C1S2-derived hybrids obtained after three MARS cycles (one cycle of recombination (C1), followed by two generations of selfing (S2), and to study yield stability under both drought-stress (DS) and well-watered (WW) conditions. For each of the 10 populations, we evaluated hybrids developed by crossing 47–74 C1S2 lines advanced through MARS, the best five S5 lines developed through pedigree selection, and the founder parents with a single-cross tester from a complementary heterotic group. The hybrids and five commercial checks were evaluated in Kenya under 1–3 DS and 3–5 WW conditions with two replications. Combined across DS locations, the top 10 C1S2-derived hybrids from each of the 10 biparental populations produced 0.5–46.3 and 11.1–55.1 % higher mean grain yields than hybrids developed using pedigree selection and the commercial checks, respectively. Across WW locations, the best 10 hybrids derived from C1S2 of each population produced 3.4–13.3 and 7.9–36.5 % higher grain yields than hybrids derived using conventional pedigree breeding and the commercial checks, respectively. Mean days to anthesis of the best 10 C1S2 hybrids were comparable to those of hybrids developed using the pedigree method, the founder parents and the commercial checks, with a maximum difference of 3.5 days among the different groups. However, plant height was significantly (P < 0.01) different in most pairwise comparisons. Our results showed the superiority of MARS over pedigree selection for improving diverse tropical maize populations as sources of improved lines for stress-prone environments and thus MARS can be effectively integrated into mainstream maize breeding programs.
    Publication
  • Improving maize grain yield under drought stress and non-stress environments in Sub-Saharan Africa using marker-assisted recurrent selection
    (Crop Science Society of America (CSSA), 2016) Beyene, Y.; Semagn, K.; Crossa, J.; Mugo, S.N.; Atlin, G.; Tarekegne, A.T.; Meisel, B.; Sehabiague, P.; Vivek, B.; Oikeh, S.O.; Alvarado Beltrán, G.; Machida, L.; Olsen, M.; Prasanna, B.M.; Banziger, M.
    In marker-assisted recurrent selection (MARS), a subset of molecular markers significantly associated with target traits of interest are used to predict the breeding value of individual plants, followed by rapid recombination and selfing. This study estimated genetic gains in grain yield (GY) using MARS in 10 biparental tropical maize (Zea may L.) populations. In each population, 148 to 184 F2:3 (defined as C0) progenies were derived, crossed with a single-cross tester, and evaluated under water-stressed (WS) and well-watered (WW) environments in sub- Saharan Africa (SSA). The C0 populations were genotyped with 190 to 225 single-nucleotide polymorphism (SNP) markers. A selection index based on marker data and phenotypic data was used for selecting the best C0 families for recombination. Individual plants from selected families were genotyped using 55 to 87 SNPs tagging specific quantitative trait loci (QTL), and the best individuals from each cycle were either intercrossed (to form C1) or selfed (to form C1S1 and C1S2). A genetic gain study was conducted using test crosses of lines from the different cycles F1 and founder parents. Test crosses, along with five commercial hybrid checks were evaluated under four WS and four WW environments. The overall gain for GY using MARS across the 10 populations was 105 kg ha−1 yr−1 under WW and 51 kg ha−1 yr−1 under WS. Across WW environments, GY of C1S2–derived hybrids were 8.7, 5.9, and 16.2% significantly greater than those of C0, founder parents, and commercial checks, respectively. Results demonstrate the potential of MARS for increasing genetic gain under both drought and optimum environments in SSA.
    Publication
  • Meta-analyses of QTL for grain yield and anthesis silking interval in 18 maize populations evaluated under water-stressed and well-watered environments
    (BioMed Central, 2013) Semagn, K.; Beyene, Y.; Warburton, M.; Tarekegne, A.T.; Mugo, S.N.; Meisel, B.; Sehabiague, P.; Prasanna, B.M.
    Background: Identification of QTL with large phenotypic effects conserved across genetic backgrounds and environments is one of the prerequisites for crop improvement using marker assisted selection (MAS). The objectives of this study were to identify meta-QTL (mQTL) for grain yield (GY) and anthesis silking interval (ASI) across 18 bi-parental maize populations evaluated in the same conditions across 2-4 managed water stressed and 3-4 well watered environments.Results: The meta-analyses identified 68 mQTL (9 QTL specific to ASI, 15 specific to GY, and 44 for both GY and ASI). Mean phenotypic variance explained by each mQTL varied from 1.2 to 13.1% and the overall average was 6.5%. Few QTL were detected under both environmental treatments and/or multiple (>4 populations) genetic backgrounds. The number and 95% genetic and physical confidence intervals of the mQTL were highly reduced compared to the QTL identified in the original studies. Each physical interval of the mQTL consisted of 5 to 926 candidate gene. Conclusions: Meta-analyses reduced the number of QTL by 68% and narrowed the confidence intervals up to 12-fold. At least the 4 mQTL (mQTL2.2, mQTL6.1, mQTL7.5 and mQTL9.2) associated with GY under both water-stressed and well-watered environments and detected up to 6 populations may be considered for fine mapping and validation to confirm effects in different genetic backgrounds and pyramid them into new drought resistant breeding lines. This is the first extensive report on meta-analysis of data from over 3100 individuals genotyped using the same SNP platform and evaluated in the same conditions across a wide range of managed water-stressed and well-watered environments
    Publication