Abstract:
The combining abilities for yield, drought tolerance and quality related traits in
Camellia sinensis
were
estimated using a 4 x 4 full diallel mating design. There was significant phenotypic variation for the nine
traits measured among the progeny and their parents. Generally, parents with good combining ability
produced progeny with above average performance for all the traits evaluated. The general combining
ability (GCA) effects were significant for all but one black tea quality trait, TF:TR, while specific
combining ability (SCA) effects were significant for fermentability, pubescence and bud weight. All the
traits but TF:TR however were predominantly governed by additive gene effects. Strong maternal
influence for all traits was evident except for thearubigins and bud weight signifying the importance of
the choice of female parents in tea breeding programmes targeting yield, abiotic stress related traits
and processing of black tea and special tea products like the silvery tips. Significant non-additive
effects were demonstrated by all traits apart from yield, TF:TR and bud weight. However, only drought
tolerance, TF and pubescence exhibited unidirectional dominance effects. The results show that the
assessed traits are highly heritable and guided breeding and judicious clonal selection would lead to
further tea improvement. Although no trait can be treated singly, utilization of open pollinated seed
targeted towards improvement of yield and black tea quality traits particularly high levels of total
polyphenols and pubescence aimed at developing a designer clone for specialty tea product would
suffice given judicious choice and inclusion of suitable progenitors in seed orchards. It is inferred that
the basic information about combining abilities is valuable for breeding of elite cultivars.
