BREAKING UP DORMANCY OF ADANSONIA DIGITATA L. SEEDS AND REGENERATION OF PLANTLETS FROM STEM NODAL SEGMENTS IN VITRO

In Yemen, there are only three trees of Adansonia digitata L. which is adopted in this study. Natural regeneration and independent germination of Adansonia digitata is poor although it is one of the tallest trees in the world that was recorded to live about 4000 years. Unfortunately, the tree is a subject of extinction. In the present study, the seeds of Adansonia digitata L. were pretreated with full and half strength of hydrochloric, sulfuric and nitric acids for one and/or two hour as a mean of scarificationtobreakthedormancyoftheseeds.Seedswerethensurfacesterilizedandallowedtogerminateonhormone–freeMS basal salts culture medium in vitro. The obtained seedlings were used as a source of nodal segments explants for propagation in vitro. Results of the present study have shown that all of the acid treatments overcame seed dormancy and enhanced seed germination in various degrees. The percentage of seed germination increased from 18.6% in the control group to 86.6% using a pretreatment of half strength sulfuric acid for one hour. The germinated seeds grown into seedlings of a mean of 11.1 centimeter after 8 weeks of growth. Stem nodal segments were cultured on agar solidifiedMSbasalsaltssupplementedwithvarious concentrations of benzyle adenine (BA) and naphthalene acetic acid (NAA). The maximum regenerant shoot length (15.1±03 cm) was obtained with 8 mg/l BA plus 0.5 mg/l NAA while The maximum number of leaves per regenernt reached up (7.2±0.2) using 10 mg/l BA + 1.0 mg/l NAA.The obtained regenerants developed roots on the same culture media. They were acclimatized for one week and then transferred to soil.