http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Genotype-environment interaction and its effects on heterotic patterns in a diallel of exotic and local maize (Zea mays L.) in mid altitude zones of Kenya
The purpose of this investigation was to determine, the effect of genotype-environment interaction on the heterotic patterns, heterotic groups, combining ability, inbreeding depression and grouping testing sites in mid altitude zones of Kenya. Fifteen F1 genotypes, six parents and fifteen F2 families were tested at Kakamega, Embu, Bukura and Alupe for two seasons in 1992/93. The genotypes differed significantly for maturity traits, plant height, ear height and yield and interacted significantly with the environments. Embu had the highest location mean yield and the genotypes took longer to reach anthesis than at other test locations. The hybrid Bunyore x Maracay 8329 had the highest yield across locations over seasons. Most genotypes had stable yield across environments. The GCA effects had greater control of the studied traits than the SCA effects except for the grain yield. The parents Bunyore, Embu 12, and Rattray Arnold 8321 had high GCA effects for yield. Hybrids, Bunyore x Maracay 8329 and Embu 11 x Pool 20 showed consistently high SCA effects at all locations during long rains. No single cross showed consistently high SCA effects during short rains. Bunyore and Maracay 8329 were the only parents, that consistently combined well in seven of the eight environments. This indicates that heterotic patterns are environment specific. The inbreeding depression that F1 crosses suffered when selfed to F2 families was greater than was expected of the varietal crosses. This could be due to competition between F1 and F2 in favor of more vigorous F1 crosses, environmental effect, genetic interactions or serious genetic load in the genotypes. Bunyore and Maracay 8329 are recommended as the base populations for Kakamega breeding program with Rattray Arnold 8321 and Embu 12 as backup populations. The Embu program could use lines from either Embu 11 or Embu 12 and cross them to lines from Rattray Arnold 8321. Maracay 8329 could be a backup population for Embu program. Exchange of test materials between Kakamega and Embu breeding programs is recommended.