The ability of callus formation from the embryo axes of coconut in different concentrations of 2,4-D was evaluated. The experimental design was completely randomized in a 4x5 factorial scheme (4 concentrations of 2,4-D x 5 segments of the embryogenic axis). The axes were excised longitudinally out of zigotic embryos and were then disinfected with sodium hipocloride (0.2%) for two minutes, washed with sterile distilled water, and soaked for two minutes in a solution of sterile citric acid (100 mg.L-1). The embryogenic axes were split in five segments corresponding to positions A, B, C, D and E, and transferred to Petri dishes containing the culture media Y3, suplemented with four concentrations of 2,4-D (10-4; 1.36x10-4; 3.62x10-4; 4.52x10-4 M), sucrose (50 g.L-1), activated charcoal (2.5 g.L-1) and vitamins of Morel and Wetmore. The Petri dishes were incubated in a dark atmosphere under the temperature of 25 ± 2ºC. After 15 days of inoculation, the segments A and B in the concentration of 10-4 M of 2,4-D presented 97.5% of explants with friable callus, and 92,5% and 80%, respectively, in the concentrations of 1.36x10-4 M of 2,4-D. The E segment, in both concentrations, presented 60% of callus formation. After 30 days of inoculation, the segments A and B promoted 100% and 97.5% in the concentration of 10-4 M, and 90% and 80%, respectively, in the concentrations of 1.36x10-4 M. The E segment promoted 55% to 57.5% of callus induction in both concentrations.
Tissue culture; growth regulators; in vitro culture