protocol for rapid in vitro propagation of genetically diverse pitaya

An efficient propagation system of pitaya with diverse genetic background was established by using tender stem as explants. Various types of plant growth regulators (PGRs) were used to determine the most effective hormone combination for shoot proliferation. Zeatin (ZT), thidiazuron (TDZ), 2, 4-dichlorophenoxyacetic acid (2, 4-D) and 6-benzylaminopurine (6-BA) alone could induce multiple shoots. In that case, the most shoots per explant i.e. 4.6 (13.68 µM ZT), 4.8 (0.11 µM TDZ), 4.3 (17.76 µM 6-BA) and 3.2 (0.23 µM 2, 4-D) were obtained. The best PGRs combination was MS medium with 3.0 µM ZT and 0.5 µM IBA producing the most shoots per explant and the most vigorous shoots. Of the two varieties and six superior selections cultured on the best PGRs combination, more than 6.0 shoots per explant were obtained. No polymorphism was detected among in vitro-derived plantlets selected at random after 11 sub-cultures. Those results showed that MS media with 13.68 µM ZT and 2.46 µM IBA was suitable for shoot propagation of diverse pitaya varieties and selections. The protocol can be used for large-scale propagation of pitaya to meet the demand of increasing commercial cultivation.