Correlations and Genetical Analyses on the Several Characteristics of the Tea Plant at the Stage of Individual Selection (Part 1)

Abstract

The correlation analyses and the statisticgenetical studies based on the analysis of variance of "biparental progenies" were made here at the stage of individual selection of the tea plants, to find the reasonable combinations and the methods of early selection in the tea breeding.The phenotypic correlation coefficients were calculated among the following characters, sprouting time, quality of black tea, plant height, yield of first crop, number of buds per plant, bud weight per 100 buds, growth weight in a year, leaf length, variation of leaf length and leaf thickness in the F1 progenies of the crosses, between a strain of Assam indigineous and japanese varieties.These ten characters were classified in three groups, sprouting time, quality and other traits concerned with growth and yield. The groups were approximately independent of each other, but intra-relationships within the third group were relatively closed.Especially, growth weight showed a close correlation with yield, so it is appeared that yield in the next year could be practically estimated by growth weight.The analyses of "biparental progenies" were used on the traits of sprouting time, plant height, growth weight, leaf length, variation of leaf length, internode length of shoot and diameter of shoot in the progenies originated from the mutual crossings among the selected Assam hybrid clones, and then phenotypic, genetic and environmental correlation coefficients and heritabilities were estimated.The results of this analyses suggested that the positive correlations of early sprouting time with plant height, diameter of shoot, and length of internode were hereditarily and environmentally significant. And early sprouting time was associated with small leaf length and small variation of leaf length hereditarily, but reversely with large these traits environmentally, also growth weight had no correlation hereditarily with early sprouting time, but environmentally closely related.Heritabilities of these characters were estimated, and the value of sprouting time was very high and the other traits showed relatively low values.And then, the genetic variance has been divided into additive genetic variance and variance due to dominance deviations on these five characters, sprouting time, plant height, growth weight, leaf extent (leaf length × leaf width) and leaf shape index (leaf length ÷ leaf width).Heritabilities in the narrow sense of sprouting time and leaf shape index were high, while plant height and leaf extent had very low heritability values.The dominance for genes concerned with sprouting time and leaf shape index was estimated to be nearly complete, and the possibility of large overdominance in the action of genes determining plant height, leaf extent and probably growth weight was indicated.In addition to the above results, some discussions were made to suitable choice of mating parents for each breeding objective.