Person:
Gakunga, J.

Profile Picture
Email Address
Birth Date
Research Projects
Organizational Units
Job Title
Last Name
Gakunga
First Name
J.
Name
Gakunga, J.

Filters

2011 - 20122
Reset filters

Settings

AGROVOC: GENOTYPE ENVIRONMENT INTERACTION ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Yield stability of stem borer resistant maize hybrids evaluated in regional trials in east Africa
    (Academic Journals, 2012) Beyene, Y.; Mugo, S.N.; Tadele Tefera; Gethi, J.; Gakunga, J.; Ajanga, S.; Karaya, H.; Musila, R.N.; Muasya, W.; Tende, R.; Njoka, S.
    Twenty-seven stem borer-resistant maize hybrids and three checks were evaluated in 14 locations in Kenya and Ethiopia to study the genotype x environment interaction (GEI) and yield stability. An analysis of variance was conducted for grain yield, number of days to silking, plant height, ear height and grain moisture content, and reaction to turcicum leaf blight, gray leaf spot, maize streak virus diseases and common rust. The yield stability and adaptation pattern of genotypes were examined with genotype plus genotype x environment (GGE) interaction biplot. Variations due to location, genotype and GEI effects were highly significant for all traits. Location variance among the hybrids was the most important source of variation for all traits, accounting for 58 to 90% of the total variance. The genotypic variance was higher than the GEI variance for turcicum leaf blight, plant height and silking date. The GEI variance was higher than the genotypic variance for grain yield, ear height, gray leaf spot, common rust and grain moisture content. The GGE biplot showed that 50% of the entries had positive PC1 scores suggesting above average performance, and 50% of them had negative PC1 scores indicating below average performance. Based on the mean grain yield and stability parameters, hybrid CKIR07003 (5.5 t/ha), CKIR07004 (5.5 t/ha) and CKIR07005 (5.6 t /ha) were identified as high-yielding and stable genotypes, and could be nominated for national performance trials for commercial release in various countries.
    Publication
  • Thumbnail Image
    Testcross performance of doubled haploid maize lines derived from tropical adapted backcross populations
    (Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Maiscoltura, 2011) Beyene, Y.; Mugo, S.N.; Pillay, K.; Tadele Tefera; Ajanga, S.; Njoka, S.; Karaya, H.; Gakunga, J.
    Doubled haploid (DH) lines produced by in vivo induction of maternal haploids are routinely used in maize breeding. The present study was carried out to assess the performance of 75 doubled haploid maize testcrosses and six checks tested across four locations in Kenya for grain yield, agronomic traits and reaction to major leaf diseases. The 75 DH lines were derived from the backcross (BC1) plants of two CIMMYT bi-parental crosses. Significant location, genotype and genotype x location effects were observed for grain yield and anthesis-silking interval (ASI). Genotypes were significantly different for reaction to leaf blight and gray leaf spot. Location explained 69% of the total phenotypic variance while both genotype and genotype by environment interaction effects contributed 4% each. Fifteen DH testcross hybrids yielded better than the best commercial check, WH505 (5.1 t/ha). The best DH testcross hybrid (CKDHH0223) averaged over the four locations yielded 29.5% higher than WH505. These results indicate that maize testcrosses developed from DH lines produced as high a grain yield and as acceptable agronomic traits as the commercial hybrids developed through conventional pedigree methods. The DH lines identified in the study may be useful for improving yield and disease resistance in maize breeding programs in eastern and southern Africa.
    Publication