Paper Title
An Efficient Protocol for Begonia Rex Micropropagation Using Different Explant Types, MS Salt Strengths and Various Plant Growth Regulators

Abstract
Through this study a reliable and efficient protocol was developed for micropropagation of begonia plant Begonia rex by tissue culture technique. Two types of explants were tested at initiation stage including leaf discs and petioles after being disinfested with NaOCl (1%) for 15 minutes and the survival rates reached 70% and 60% respectively. The initiated shoots were successfully multiplied by the addition of BA and kinetin to the culture media especially at 4.0 mgl-1 and 7.0 mgl-1 of both cytokinins respectively. Kinetin was more effective than BA at the same or higher levels added to the multiplication media. The micro-shoots were rooted on MS medium enriched with 0.75 mgl-1 NAAby giving 75% rooting percentage, 75.00 roots per explant as the highest number of roots equaled to those produced by 1.5 mgl-1 NAA and the longest roots (6.65 cm) which were significantly higher than the control treatment. Generally, NAA performed better than IAA and IBA at rooting stage of begonia micro-shoots. On the other hand, while testing the effect of different MS salt strengths on rooting stage with the addition of the best treatment from the previous experiment (0.75 mgl-1 NAA), the highest rooting percentage (90%) was achieved from the culture of micro-shoots on half strength MS salts which was higher than 75% rooting percentage obtained from both full and quarter MS salt strengths. The produced plantlets, were successfully acclimatized and transplanted to the open air conditions with a high survival rate estimated at 75%. Conclusion: It is clear that through applying this micropropagation protocol for begonia is very effective and reliable and it is highly recommended for local nurseries toward mass production of this economically important plant with low cost projects. Keywords - Begonia, Begonia Rex, Micropropagation, Plant Growth Regulators, MS.