In vitro propagation of Citrus maxima (Burm) Merr.

A system for in vitro propagation of pummelo orCitrus maxima (Burm) Merr. was established using shoot-tip and single-node stem segment taken from young seedlings. The procedure involved the initiation of shoots from explant tissue, followed by shoot proliferation, in vitro rooting, and finally, hardening of plantlets and potting out in soil. The agar-solidified Murashige and Skoog (MS) medium containing 30 g/L sucrose and supplemented with 0.2 mg/L BAP, 0.5 mg/L IBA and 40 mg/L adenine (MSI medium) was optimum for shoot initiation from both explants. For rapid shoot proliferation, the MS medium containing 0.5 mg/L BAP, 0.5 mg/L IBA and 40 mg/L adenine (MSP medium) was optimum. Eight-week-old shoots efficiently produced roots in agar-solidified MS medium containing 0.5 to 1.0 mg/L IBA compared with 4-wk-old shoots, indicating the importance of an adequate shoot growth prior to root induction.Using this system, 126 transplantable plantlets and 494 6-wk-old shoots can be produced from one nodal explant in a 4-month micropropagation cycle. One shoot tip explant can produce 26 transplantable plantlets and 50 6-wk-old shoots after 4 months.