In vitro micrografting of lentisk (Pistacia lentiscus L.) on Pistacia species (Pistacia vera L., Pistacia khinjuk Stocks, Pistacia atlantica Desf. and Pistacia terebinthus L.)

The success of in vitro micrografting of shoot tips of juvenile lentisk (Pistacia lentiscus L.) has been examined. Surface sterilization methods for mature seeds of 4 Pistacia species were developed. The mature dry nuts of Pistacia vera L., Pistacia khinjuk Stocks, Pistacia atlantica Desf., Pistacia terebinthus L. that germinated in vitro were used as rootstocks: Ten- to 14-day-old (for P. vera L. and P. khinjuk Stocks) and 8 weeks (for P. terebinthus L. and P. atlantica Desf.) in vitro seedlings after decapitation above the cotyledons. Growth characteristics such as root length, shoot length and shoot diameter of all four species during the development of micrografts were determined in the tree different growth media: (1) 0.5 mgl-1 BAP + 0.1 mgl-1 IBA, (2) 0.5 mgl-1 IBA + 0.1 mgl-1 BAP and (3) the control group (without plant growth regulator). Shoot tips derived from axenic germinated mature seeds of lentisk micrografted onto in vitro juvenile rootstocks of P.vera L., P.khinjuk Stocks, P. atlantica Desf., P. terebinthus L, resulted in the restoration of shoot-bud proliferation with a 100% uccess with all combinations when the rootstock was decapitated to remove all leaves and a vertical slit was made on the stump; the scion base, cut in a v-shape, was fitted to the slit. Variables tested include a size of microscion and effects of culture medium were used in oder to determine the micrografting success. The mean shoot diameter, shoot length and root length varied according to the rootstock types. The growth of rootstocks from mature seeds of P. vera L. and P. khinjuk Stocks were developed faster than P. terebinhus L. and P. atlantica Desf. Plant growth regulator free MS medium was the best germination medium for all species but 0.5 mgl-1 BAP + 0.1 mgl-1 IBA supplemented MS medium was used for the development of rootstocks because the development of roots was generally inhibited in this treatment. The best growth of rootstocks was obtained with the in vitro germinated mature seeds of P. vera L. and P. khinjuk Stocks rather than P. atlantica Desf. and P. terebinthus. Slow growth of shoot and longer root developments for P. atlantica L. and P. terebinthus was noticeable when the seeds were cultured on the IBA containing germination medium. The best responses for root length of P.vera L., P.khinjuk Stocks, P. atlantica Defs. and P. terebinthus L. was,34.43 mm , 44.53 mm mm, 28.58 mm and 16.83 mm, respectively. The 14-day-old seedlings of P.vera L. and P.khinjhuk Stocks were used as rootstock because the mean shoot diameters for P. vera L. and P. khinjuk Stocks were reached to 2.38 mm and 1.44 mm, respectively two weeks after culture. The seedlings of P. atlantica Desf. and P. terebinthus L. were developed slow and became ready for micrografting two months after culture. Shoot tips from juvenile lentisk micrografted onto in vitro juvenile rootstocks resulted in the restoration of shoot bud proliferation with a 100% success in all treatments tested. Root development of the micrografts was directly related with the length of the microscion used. The better root growth of micrografts was obtained with the 1.5 cm long shoot tips rather than 0.5 and 1.0 cm microscions. Slow growth and lack of axillary shoot development on the micrografts was noticeable when the micrografts were cultured on plant growth regulator-free medium. In vitro micrografted plantlets were successfully acclimatized and no problems were encountered with the establishment of micrografted plants in vivo. This study may be an efficient protocol the establishment of a micrografting protocol for clonally propagating mature lentisk genotypes may be an efficient technique overcoming conventional lentisk propagation problems because P. lentiscus L. is a shrub or dioecious tree, with separate male and female plants, and it needs several years to become a tree form by budding up to 5 m high in order to cultivate for its aromatic resin. It is expected that the micrografted plants will have one stem and several axillar branches. Key words: Lentisk, Micrografting, Pistacia lentiscus L., Vegetative propagation