Genetic variation is important in breeding programs because it determines the amount of gain from selection. This study was conducted to determine the magnitude of genetic diversity in coffee (Coffea Arabica L.) acces...Genetic variation is important in breeding programs because it determines the amount of gain from selection. This study was conducted to determine the magnitude of genetic diversity in coffee (Coffea Arabica L.) accessions for developing superior cultivars in Rwanda. Twenty-one coffee accessions established in 1990 in an un-replicated field experiment at the Rubona Experimental Station of the Rwanda Agriculture Board (RAB) located in the mid-altitude zone of Rwanda, were used in the study. Data were recorded on three randomly selected trees on eight quantitative morphological traits in each accession in 2013. One-way analysis of variance (ANOVA) indicated highly significant (p 0.01) differences among the accessions for number of primary branches, number of leaves per branch, number of cherries per internode and % coffee leaf rust disease rating;and significant (p 0.05) for yield, but not for internode length, weight of 100 cherries, and number of internodes per branch. Multivariate analysis showed that the first three principal components contributed cumulatively to 78.3% of the total variation. The PCA biplot grouped all the accessions into three different clusters and one singleton. The first and second PCs accounted for 43% and 21%, respectively. Cluster I and II grouped accessions with valuable quantitative agronomic traits while accessions in cluster III exhibited poor agronomic performance. The highest inter cluster distance of 475 was observed between cluster I and II, and the highest intra-cluster distance (62) was in cluster II. The phenotypic markers provided a useful measure of genetic distances among the coffee accessions and identified potential donors for future breeding efforts.展开更多
文摘Genetic variation is important in breeding programs because it determines the amount of gain from selection. This study was conducted to determine the magnitude of genetic diversity in coffee (Coffea Arabica L.) accessions for developing superior cultivars in Rwanda. Twenty-one coffee accessions established in 1990 in an un-replicated field experiment at the Rubona Experimental Station of the Rwanda Agriculture Board (RAB) located in the mid-altitude zone of Rwanda, were used in the study. Data were recorded on three randomly selected trees on eight quantitative morphological traits in each accession in 2013. One-way analysis of variance (ANOVA) indicated highly significant (p 0.01) differences among the accessions for number of primary branches, number of leaves per branch, number of cherries per internode and % coffee leaf rust disease rating;and significant (p 0.05) for yield, but not for internode length, weight of 100 cherries, and number of internodes per branch. Multivariate analysis showed that the first three principal components contributed cumulatively to 78.3% of the total variation. The PCA biplot grouped all the accessions into three different clusters and one singleton. The first and second PCs accounted for 43% and 21%, respectively. Cluster I and II grouped accessions with valuable quantitative agronomic traits while accessions in cluster III exhibited poor agronomic performance. The highest inter cluster distance of 475 was observed between cluster I and II, and the highest intra-cluster distance (62) was in cluster II. The phenotypic markers provided a useful measure of genetic distances among the coffee accessions and identified potential donors for future breeding efforts.
