Studies on improvement of 'West Coast Tall' cultivar of coconut for yield and resistance to root (wilt) disease through recurrent selection
In India, coconut is grown in 2.14 million hectares, and about 10 million people depend on coconut for their livelihood. Among the diseases affecting coconut, root (wilt) is the most serious. Cultivation of resistant varieties is the most ideal and practical solution for disease management. A comprehensive breeding programme for resistance to root (wilt) disease aimed at improving the local tall ('West Coast Tall') cultivar through recurrent selection was initiated in 1987. Disease-free, high-yielding palms found in the midst of heavily diseased palms and located in disease hotspots were selected as the base material for the breeding programme. The selected disease-free palms were selfed and inter se-mated since 1990 to produce two sets of first generation progenies (viz., self and inter se-mated). The first-generation progeny were planted during 1994-95 in experimental fields, which were hotspots of root (wilt) disease, in order to screen and select high yielding, disease-resistant palms. Observations recorded 18-19 years after planting revealed that the disease incidence in inter se-mated progenies was only 47% compared with 63% in selfed progenies. The inter se-mated progenies had 35-40% higher nut yields compared with selfed progenies and were also superior with regard to nut characteristics. A total of 40 high-yielding and disease-free palms belonging to the first generation were selected during 2009-10 to produce second-generation progenies for further evaluation, selection and crossing. Analysis of population structure of the mother palms and first-generation progeny using SSR markers, indicated higher values for inbreeding coefficient and homozygozity in subsequent generations. The inter se-mated progenies were superior to selfed progenies with respect to nut yield and resistance to root (wilt) disease.
Thomas, R.J., Shareefa, M., Nair, R.V., Jacob, P.M., Sasikala, M., Rajesh, M.K. and Karun, A. (2016). Studies on improvement of 'West Coast Tall' cultivar of coconut for yield and resistance to root (wilt) disease through recurrent selection. Acta Hortic. 1127, 141-148
coconut, root (wilt) disease, resistance breeding, sib-mating inbreeding, genetic diversity, microsatellite