Abstract
An evaluation of stability of thirty Arabica coffee genotypes was carried out across different environments. The interaction of genotype by environment (G x E) across the different environments was highly significant. Both heterogeneity of regression and pooled deviation mean square from regression were highly significant. On this basis stability analysis was done using regression and AMMI models. On the basis of the analyses, different sets of genotypes were found as stable by the two models. Genotypes 7803A and 7803B, which were at the 13 th and 14 th ranks from thirty genotypes, were found as stable by the regression model. On the other hand genotypes 8143, 75187B and 8019, which were at the second, third and seventh ranks, were found as stable by the AMMI model. The discrepancy noticed in the two models in indicating the stable genotypes was largely attributed to their differences in accounting the interaction sum of squares. The result of the study is considered as one remarkable success in the history of Arabica coffee research as identifying stable genotype for multi-locations / diverse environments has long been a major challenge and in practice able for decades.
Highlights
Arabica coffee is avital crop in the national economy of Ethiopia
This was further proved from the poor adaptation of the coffee berry disease resistant (CBD) varieties released for south-western Ethiopia when grown at the Eastern geographic region of the country (Mesfin, unpublished)
The combined analysis of variance revealed that the mean squares of genotypes, environments and genotype by environment interaction were highly significant (Table 3)
Summary
Arabica coffee is avital crop in the national economy of Ethiopia. Substantial proportion of the people in the country one way or the other earns their livelihood from coffee production or its trade. The result of their study confirms the fact that varieties that exhibit better adaptation at one location in one coffee growing region do not perform well at other locations of a different geographic region This was further proved from the poor adaptation of the coffee berry disease resistant (CBD) varieties released for south-western Ethiopia when grown at the Eastern geographic region of the country (Mesfin, unpublished). Adaptation tests carried out elsewhere in other countries confirms the presence of significant interaction effect of genotypic performance across different environments (Agwanda and Owuor, 1989; Agwanda et al, 1997; Montagnon et al, 2000) These workers reported that it is possible to identify stable varieties and minimize risk of crop failure that could result from genotype by environment interactions. Since Ethiopia has both wide genetic diversity of arabica coffee and diverse environments for growing it, conducting adaptation tests across different locations within region is important to identify stable genotypes and increase productivity and production of Arabica coffee across the different environments
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