Abstract
This study investigated the effects of gamma irradiation doses and mannitol levels of lavender (Lavandula angustifolia Mill.) cultured on solid MS medium. The effects of different growth regulators concentrations on lavender explant growth were also studied. For the first experiment, shoots of Lavandula angustifolia Mill were sterilized with different Sodium hypochlorite concentrations (15%, 20%, 25%, and 30%) for 10 min. Growing the lavender explants on MS medium sterilized with 25% Cl produced the highest survival percentage (88.59%). The results indicated that maximum numbers of shoots and leaves of lavender plants were produced on MS medium enriched with 2 mg/L BA, which also produced the maximum callus induction. Growing the lavender explants on MS supplemented with 1.0 BA gave the longest shoots (4.40 cm/ explant). Adding 2 mg/l IBA to MS medium enhanced root growth and significantly increased the average number of roots (3.40 roots/explant) and root length (2.33 cm/explant). Exposing lavender explants to gamma irradiation at high doses (8 krad) decreased lavender growth to the lowest values. A low dose of gamma rays (2 krad) significantly increased the average growth parameters to the highest values when compared with the control. Moreover, increasing mannitol levels induced an adverse effect on the lavender growth control. That decrease was proportional to the level of mannitol, but the total indoles and phenols and reduced sugar increased to their maximum tolerance for drought stress. The highest non-reducing sugar content (12.7 mg) was produced with 20 g/L mannitol when compared with the control. Gamma rays induced changes in the lavender chemical composition in this study.