Callus induction and plant regeneration of Juniperus excelsa using in vitro technique

Low germination and non-viability of embryos are the main hindrans for forestation of Juniperus excelsa. Conventional methods of asexual plant propagation of this species have not been successful so far. In order to in vitro propagation, small pieces of stem of 8-10 years old trees(10-15 mm long) containing shoot tips with needles fascicles were used as explants. Those were excised from the plants and after surface sterilization. Samples were cultured on a Murashige & Skoog (MS) medium and six revised MS medium supplemented with different concentrations of BAP, Kin, IBA, NAA and 2,4-D. Then the cultures were incubated in a climate chamber at temperatures of 25°C (for day) and 15°C (for night) and 12 hours light at 2000-2500 Lux with 75% humidity. Results indicated that callugenesis and callus growth restricted by both type and nitrate and hormonal source. The best simulation of callus growth occurred on cultures of without KNO3, with gloutamin (100 ml/l) and amount of 2,4-D/BAP at more than 1 ratio. Although adventitious buds were formed on juvenile stages of parent plants, but root induction did not occur. In addition, the season of sampling can also restrict the calogenesis. Such, calougenesis of collected plants in autumn was more than in spring. We could not find any shoot proliferation on medium MS, however by elimination of ammonium nitrate from medium MS bud appeared from callus as well as leaf blade.