TY  - POS
AU  - Magorokosho,C.
AU  - Banziger,M.
AU  - Betrán,J.
TI  - Genetic diversity and agronomic performance of southern african maize varieties under abiotic stresses
PY  - 2009///
CY  - Shangai, China : 
PB  - SAGC, 
KW  - Genetics
KW  - AGROVOC
KW  - Maize
KW  - Varieties
N1  - Poster Abstract; Presented at International Conference on Integrated Approaches to Improve Crop production Under Drougt-Prone Environments (INTERDROUGHT), 3; Shangai, China, 11-16 Oct, 2009
N2  - Large scale and planned introduction of maize (Zea mays L.) in southern Africa was accomplished during the last 100 years. Since then, smallholder farmers and breeders have been selecting varieties best adapted to their specific growing conditions and market needs. A study was conducted in 2004 and 2005 to assess the variability and performance of a core set of maize varieties collected in Zimbabwe, Zambia and Malawi. A total of 108 varieties comprising ancestral open pollinated varieties (OPV) introductions originating from the USA, early generation OPVs developed in southern Africa around the 1900s, traditional landraces and improved varieties were evaluated under low soil nitrogen, low soil pH, drought stress, random stress, and under optimum moisture and fertilizer levels. Results obtained showed the existence of considerable variation in agronomic traits under the different environments. Differences among the accessions, type of accessions (landraces, ancestors, early OPVs and improved) were significant for most of the traits studied. Genotype x Environment (GxE) interactions were also significant. Agronomic performance of maize varieties under different environments was used to create dendrograms, where materials were clustered into groups based on respective performance under specific environments. Estimates of broad sense heritabilities varied depending on traits and testing environments. However, these estimates were generally larger for each trait in the environment where the variance of that trait was highest. Genetic and phenotypic correlation coefficients also varied depending on traits and testing environments. Biplots constructed revealed which traits were closely related for each environment. Generally improved varieties outperformed landraces under all environments, but there were notable exceptions with many landraces yielding as much as improved varieties. Landraces were more stable than improved varieties across test environments, but improved varieties were more responsive to favorable growing conditions. The most promising landraces for pre-breeding and further investigation were identified
UR  - http://libcatalog.cimmyt.org/Download/cis/G93651.pdf
ER  -