Physicochemical analysis of Ugandan tea (Camellia sinensis) germplasm reveals potential commercial green and black tea varieties

Tea (Camellia sinensis L.) is an important beverage consumed worldwide. In Uganda, it is the second-largest and highly prioritized export crop after coffee and provides the much-needed jobs to more than 800,000 people. Despite its importance in the country, the crop has received very limited research attention for its improvement and optimal utilization. This study was aimed at characterizing existing tea germplasm in Uganda to inform future breeding initiatives for market-preferred tea varieties. Fifty-eight advanced tea clones were randomly selected from the tea germplasm conserved at Uganda's Tea Research Center in Rwebitaba and analyzed in the laboratory for eight physicochemical descriptors. Hierarchical cluster analysis performed on the 58 clones using Cluster-R package revealed four main clusters, indicating the existence of variation for physicochemical parameters within tested germplasm. This variation can be exploited to select among and/or improve the studied germplasm genetically for quality. High fermentation rate, which is one of the key indicators for good-quality black teas, revealed 15 fast-fermenter tea clones. Clone "UTR12/12" was identified as the most rapid fermenter, fully fermenting within 30 min, which implies a good clone for black tea. The clone also had the highest polyphenol content (26.7%), higher than the highquality clone "UTR6/8" (control). Other tea clones whose polyphenol content was within the range of the control black tea clone were: "UTR144/10" (20.9%) and 'UTR144/17, (20.66%). The identified promising black tea clones can be advanced to multi-location trials for further evaluation and selection for eventual variety release as commercial black-tea clones.