Decline of cocoa plantations in Amazonia has been attributed to Witches-broom-disease (Crinipellis perniciosa). An interspecific hybrid (Theobroma grandiflorum x T. obovatum) has demonstrated resistance to this disease. Calogenesis of this hybrid was evaluated, in preparation for its mass propagation. The explants used (tegument, cotyledons and embryos) were developed in sterile conditions in LPm media plus coconut milk (50 ml/l), glucose (20 g/l), 2,4 - D (2 mg/l), Thidiazuron - TDZ at concentrations of 0, 5 e 10 µg/l, and activated charcoal (2 g/l) in gelrite (2 g/l) at pH 5.8. Each concentration of TDZ x kind of explant was considered a treatment and were kept in the dark at a temperature of 22 ± 2 ºC. Explants did not show significant differences in the proportion of callus recovery (p= 0,14) although cotyledons did have the highest value. TDZ level did not influence callus recovery (p= 0,94). Different explants resulted in different frequencies of callus development (p= 0,023) but were not been influenced by the doses of TDZ (p = 0,66). Cotyledon explants displayed the highest values for frequency of callus development. There was also a slight trend that lower levels of TDZ resulted in higher frequencies of callus development. There was no interaction between kind of callus/flasks x doses of TDZ (p = 0,32).
cupuassu hybrid; tissue-culture; witches-broom-disease; micropropagation
