Morphological traits based genetic diversity assessment of Ethiopian potato [Plectranthus edulis (Vatke) Agnew] populations from Ethiopia

Ethiopian potato syno Ethiopian dinich [Plectranthus edulis (Vatke) Agnew], is one of the ‘orphans’ and ‘neglected’ indigenous edible tuber crops in the country. Nowadays, the crop, both the cultivated and wild forms, are close to total extinction partly because of climate change, habitat instability, and very little research intervention targeting its improvement and conservation. Hence, in the present study, we intended to generate baseline information through morphological traits based genetic diversity estimation that is useful for improvement and conservation actions. We tested 174 populations at three experimental locations using alpha lattice design with two replications/location and three blocks/replication/location following appropriate management practises. Data were recorded for 12 qualitative and 16 quantitative traits and analysed using Statistical analysis software 9.0, MINITAB® 14.13 and FigTree v1.4.3 packages. A wide range of variations and mean performance values have been recorded for the phenetic traits, suggesting the existence of considerable variations for use in breeding and conservation. Analysis of variance revealed a highly significant (p < 0.001) variation among the populations and non-significant environment-population interaction for most of the quantitative traits, implying the minimal environment effect on their expression. High genotypic coefficients of variation, coupled with a high estimate of broad sense heritability and high genetic advance as a percent of population mean, were observed in tuber weight per hill, number of primary branches per plant, tuber number per hill and number of plants per hill with eventually large magnitude of positive phenotypic and genotypic correlation with tuber yield per hectare. This result suggests importance of the traits in selection program that targets tuber yield improvement. Principal components analysis revealed about 77% of the total variation for the first six principal axes with high factor loadings again from the same traits. The populations were grouped into four clusters but weak region (zone) of origin-based pattern implying the historical or contemporary gene flow, specially germplasm (tubers) exchange among the regions (ethnicities). In general, there is high genetic-based variability for Ethiopian potato improvement and conservation. However, more collections and evaluation over multiple locations and seasons are recommended for well-refined genetic diversity estimation.