dc.description.abstract | Selection of eucalyptus genotypes with wide adaptability across diverse environments IS
important for adoption recommendation. When selecting superior genotypes one is usually
confronted with the problem of genotype by environment interaction. An extension of analysis of
variance (ANOVA) for studying genotype by environment interaction (GEl) is Additive Main
Effects and Multiplicative Interaction (AMMI) Model, which is a hybrid analysis that
incorporates both additive and multiplicative components of a two way data structure. This study
applied AMMI to evaluate genotype by environment interaction of eucalyptus species in Kenya
grown at different locations, determined genotypes stability and pattern of response across
environmental sites. The model is applied to data on eucalyptus research undertaken by Kenya
Forestry Research Institute (KEFRI) for the tree improvement programme from 1998 and
assessed till 2006 with an aim of determining stable and adaptable genotypes across the diverse
environmental sites. The trials were set in a randomized complete..block design replicated two to
four times. The combined analysis of variance indicates that environments (E), genotypes (G)
and genotype by environment interaction (GEl) effects were significant, suggesting differential
responses of the genotypes and the need for stability analysis. Analysis of variance for AMMI
model revealed that two interaction principal components (IPCAs) were significant by using
Gollob's F- test and accounted for over 90o/~of GE interaction. Therefore, successful genotypes
need to be adapted to a broad range of environmental conditions in Kenya in order to ensure their
yield stability and economic profitability. Of the Eucalyptus hybrid clones experimented across
sites GC 14 ,GC 581, and GC 642 were found to be most stable genotypes for the highlands
while GC 540 ,GC 514, and GC 14 were found to be most stable genotypes for the lowland
environments implying they can be planted in a wide range of environments similar to the one
tried. This resolves the complication of tree breeding program, where breeders are particularly
interested in searching for fewer- widely adapted genotypes. The interaction was best predicted
by the first two principal components of genotypes and environments. Consequently, bi-plots
generated using genotypic and environmental scores of the first two AMMI components can help
breeders have an overall picture of the behavior of the genotypes, the environments and GEls.
The AMMI and ASV were found useful in describing GEl of various eucalyptus clones.
Key words: Eucalyptus clones, genotype by environment interaction (GEl) and Additive Main
effect Multiplicative Interaction (AMMI). | en |