Culture of Shoot Apices of Theobroma cacao

Surface sterilized buds of young cocoa plants (Theobroma cacao L.) taken at particular stages of the flush cycle were placed in Linsmaier and Skoog agar medium supplemented with a range of growth regulators. Only buds taken at the 1–2 (dormant) stage of the flush cycle and treated with gibberellic acid (GA₃) alone and GA₃plus kinetin (KN) supplement showed bud opening. In liquid Linsmaier and Skoog medium buds isolated at the 1–2 stage also responded to GA₃ and KN. In this case addition of KN caused bud opening, while GA₃ either initiated bud opening only or opening followed by leaf expansion depending on the concentration of GA₃ supplied. Bud development was inhibited when ABA was included in the medium hut this was overcome by the presence of GA₃ but not KN. Since a hormonal supplement was required for any response from the excised buds, it is suggested that the intermittent growth of the shoot apex in the intact plant may be determined by hormonal stimuli derived from other parts of the plant. The findings also indicate that the bud apices could be maintained in culture for long periods which may provide a basis for the development of a micropropagation procedure for cocoa.