Effects of different cytokinins on in vitro multiplication of Prunus 'Capdeboscq' rootstocks

Rootstocks for peach trees are obtained in Brazil from seeds without genetic uniformity or health guarantee. Micropropagation techniques supply genetically uniform shoots but the in vitro culture protocols must be optimized. Cytokinins are essential for breaking the apex dormancy and inducing auxiliary shoot proliferation that influence the success of in vitro multiplication. The objective of this study was to assess the effect of different cytokinins in vitro multiplication rate, and on the survival rate of apical and axyllary buds in the establishment of Prunus ‘Capdeboscq’ rootstocks. Apical and axyllary buds were inoculated in test tubes containing 10mL Lepoivre culture medium, supplemented with BAP (0.5 mg L -1 ). After two subcultures of the in vitro establishment process, 1-2 cm nodal segments were treated with kinetin, isopentenyladenine and BAP, at concentrations of 0.1; 0.5; 1.0 and 2.0 mg L -1 . At the in vitro establishment phase, stem tips presented greater survival, less contamination and no hyperhidricity. BAP gave the highest in vitro multiplication rate, with 25.9 shoots/explant at the 1.5 mg L -1 . The different cytokinins did not result in differences in shoot height. The best results for the number of shoots greater than 20 mm were obtained with BAP at 1.0 mg L -1 .