Estimation of genetic parameters from specific crosses of cocoa (Theobroma Cacao L.)

Abstract

The research project entitled 'Estimation of genetic parameters from specific crosses of cocoa (Theobroma cacao L.)' was carried outean ongoing experiment of Cadbury-KAU Co-operative Cocoa Research Project (CCRP), College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur during 1998-99. The studies were conducted in four year old hybrids. The major objectives were to study the genetic variability, heritability, correlation of different traits with yield, extent of heterotic expression of various traits and to examine the association between seedling vigour and yield. Twenty five cocoa hybrids were maintained in randomised block design with three replications. The hybrids exhibited significant variability for most of the traits studied. The estimates of pev were higher than gcv for all the traits studied. The highest heritability was recorded for number of beans per pod and seedling vigour recorded as °HD2 (6 MAS) had a high genetic gain. Yield and number of pods per tree recorded moderate genetic gain. Yield was found to be significantly and positively correlated with number of pods per tree, height (2 YAP) and girth (2 YAP) of the tree. Absence of significant correlation between yield and seedling vigour was observed. Path analysis revealed the importance of pod number per tree and wet bean weight per pod in determining yield. Yield and number of pods per tree showed a very high heterotic expression in most of the hybrids. Among the 25 cross combinations H23 was identified as the superior cross combination followed by H16 and H; The parents of

these cross combinations can be used for raising biclonal seed gardens, as they had a good specific combining ability. The floral traits did not vary markedly in the hybrids. However the qualitative traits exhibited wide variation in the different hybrids.