Genetic analysis of yield attributes in cocoa

Abstract

Genetic analysis of yield attributes in cocoa (Theobroma cacao L.) was carried out in College of Horticulture, Kerala Agricultural University, Vellanikkara, Trichur during the period 1992-93. Observations recorded on 16 characters including yield and yield attributes in 244 trees consisting of 19 hybrids and 15 parents revealed that variability in most of the characters were almost same for both the parent and the hybrid populations. Variability was maximum for yield expressed in terms of wet bean weight per tree, and number of pods. It was moderate for pod weight, wet bean weight per pod, dry bean weight and ratio of dry bean weight to wet bean weight. Hybrids showed significant diference among themselves for almost all characters. Yield, number of pods, fruit wall thickness at furrow, seed width, seed thickness and the ratio of dry bean weight to wet bean weight did not show significant difference among the parents. Parents, which are budded progenies of a single tree showed high amount of within variability. The wihin variability is ascribed to non- genetic reasons. Hybrids were more uniform and better yielding than parents. High heritability was obtained for pod length, pod weight, wet bean weight per pod, dry bean weight and number of beans per pod. Hertability was moderate for number of pods, pod width and seed thickness. Genetic divergence studies showed that the 34 genotypes did not show a natural grouping indicating that the genotypes were genetically similar. Path coefficent analysis revealed that number of pods contributes the maximum to yield followed by wet bean weight suggesting that selection based on number of pod and wet bean weight per pod would be effective in increasing yield. This experiment conveys that there is ample scope for hybridisation in cocoa. High yielding genotypes may be used as parents for hybridisation and high yielding progenies identified. These may be utilized in establishing poly cross gardens, thereby increasing the frequency of favourable genes in the population. Seeds from such gardens can be used for raising commercial plantations.