Genotype-environment interactions in tea (Camellia sinensis L.) and their implications in tea breeding and selection

Abstract

SUMMARYAn analysis of yield data from 31 tea clones grown in replicated trials at four locations revealed the presence of significant genotype-environment interactions. Joint regression analysisshowed that a significant proportion of these interactions could be attributed to differences in the linear response of each genotype (clone) to the range of environments. However, estimates of the deviations from regression were also significant, indicating the presence of some unpredictable variation.The response of each individual clone was estimated by computing the regression coefficient of individual yield on environmental mean yield at each location. The clones used in this study had regression values ranging from 0·19 to 2·08, indicating considerable genotypic difference in response to environmental change. Genetic variation in adaptation was also found to be present. Clones of the Assam type were found to possess general adaptation whereas the one clone of Indo-Chinese origin was specifically adapted to low-yielding environments.Some known features of several tea clones are explained on the basis of the linear regression model and a more scientific basis is provided for the recommendations of clones for differentdistricts. The implications of genotype-environment interactions in practical tea breeding and selection are also discussed.