Characterization and Genetic Diversity of Tea (Camellia sinensis (L.) O. Kuntze) Genotypes for Waterlogging Tolerance

Tea estates in Bangladesh are currently experiencing frequent waterlogging stress due to heavy rainfall or flooding under changing climate scenarios. The development of waterlogging-tolerant tea cultivars is, therefore, crucial for sustainable tea production with increased yield in waterlogging-affected areas. In this study, a total of two hundred tea genotypes were screened for waterlogging tolerance based on yield and quality potentials. Tea genotypes were raised at the nursery and evaluated with 13 traits at the seedling and mature stages. Descriptive and multivariate analysis of the recorded data of measured traits were performed for clustering the studied genotypes in relation to their yield and quality potential. The 200 tea genotypes were categorized into six clusters and the measured traits were classified into two groups. Cluster-5 comprised 46 closely related tea genotypes whereas other clusters-Cluster-1, 2, 3, 4, and 6 contained 39, 20, 24, 29, and 42 genotypes, respectively. PCA-biplot showed that the first two principal components (PC 1 and PC 2) cumulatively described 56.9% of total variations. From the genetic diversity analysis, the characteristics like green leaf yield (GLY), plucking points (PP), spreading of bush and number of pubescence (NP) exhibited high to moderate heritability, indicating to consider these traits as selection criteria for tea breeding program. The trait GLY showed a strong positive correlation with PP, and SBF and a negative association with PI and DR. The key quality trait, QSB had a positive correlation with SF and NP. Based on these studied descriptors, a total of 11 tea genotypes were selected, found potential for waterlogging tolerance, and can be considered for varietal improvement programs.