Direct regeneration of Birch (Betula litwinowii) by in vitro culture nodal explants

Birch (Betula sp.) is considered as a survivor of Caspian primary forests and one of the extinct forest trees in Iran. In our country، Birch species is endangered because of limited distribution range، unfavourable habitat conditions، lack of regeneration in natural habitat and inability to reproduce sexually in condition. Therefore، using the technique of in vitro is very important to support this species. The objective of this study is to optimize culture medium and surface sterilization treatments for B. litwinowii micro-propagation، that is one of known Birch by use of nodal explants. Nodal explants were collected randomly from 4-5 years old of birch seedlings and sterilised by applying different treatments in both MS and WPM medium with various concentrations of BAP and NAA hormones were cultured. The obtained data were analyzed based on completely randomized design using SPSS and MSTATC software. The results revealed that HgCl2 (0. 1% for 7 min) was the best treatment for surface sterilization of nodal explants. TheMS and WPM media supplemented with various concentrations of hormones were suitable for culture establishment of nodal explants. More than 70% of single lateral bud nodal in both mediums becomes to leaves. Finally، 10% of nodal explants are able to produce shoot and roots in WPM medium.