Genetic improvement of cocoa for resistance to swollen shoot disease through mutation breeding and in vitro culture techniques

Various tissues (vegetative buds, pollen and selfed beans) of three cocoa types were irradiated with gamma rays with the view to inducing mutants resistant to cocoa swollen shoot virus (CSSV). To save time and space in cocoa mutation breeding, certain aspects of the tissue culture techniques in cocoa were also investigated. Efforts were made to delimit some of the factors crucial to producing plants via cocoa tissues in vitro. Use of concentrations of 2-4 mg/L of BAP coupled with weekly subculturing and light durations between 16-20 hours at 2000 lx greatly enhanced differentiation, plantlet growth and plant production. Indications are that the possibility of using in vitro techniques for mutation breeding in cocoa could be exploited. 5 refs, 1 fig., 6 tabs