In vitro-derived and sterilized shoots of Cordyline terminalis were used as explants in this study. In order to investigate the effect of some amino acids and vitamins (as medium constituents) on the growth of cordyline in vitro, a recommended medium by Awad et al, (2008a) was used in all experiments. That medium contained 60 g/ L banana pulp, ½ MS, 30 g/ L sucrose and 2 g/ L gelrite. As for the effect of amino acids on shoot number/explant, results indicate that sporadic responses were observed with the used treatments, but the addition of arginine at 25 or 50 mg/ L in the recommended medium replacing glycine significantly increased shoot number/explant in all records (three records) compared to the other treatments. However, Serine at 100 mg/ L significantly showed a similar high number of shoots in all three records. In that concern, glycine (at 2mg/L as in MS) showed lower response in the third record (after 4 months). Some sporadic treatments of amino acids surpassed glycine {as in MS medium (2mg/ L)} in enhancement the colour intensity of cultures. However, that significant increase in colour intensity was only observed during all records (three records) with glutamine at 100 mg/ L and serine at 25 mg/ L. Although, glycine (2mg/ L) observed a significant increase in the growth vigor in the third record only, but some other treatments showed the same high response in all records such as 100 mg/ L glutamine and asparagine at 50 or 100 mg/ L. Concerning the vitamins when examined each alone, medium free of vitamins (control) observed significant increase in shoot number/explant of cordyline compared to the medium contained thiamine at normal level as in MS (0.1mg/ L) or higher level (0.5mg/ L). Using pyridoxine alone at lower level 0.1mg/ L), than that used in MS medium (0.5mg/ L), showed significant high response in shoot formation especially at the third record (after 4 months from culturing). In the final record (3rd record) results show that nicotinic acid at (0.10 mg/ L) showed a significant increase in shoot number when compared to the higher one (0.50 mg/ L as in MS) and the control (free of nicotinic acid). It was clear that the presence of any of those vitamin alone at 0.1 or 0.5 mg/ L was effective in enhancement both colour intensity and growth vigor of cultures compared to control medium.
Combining more than one vitamin in the medium indicated that, although different combinations illustrated positive responses in all measured parameters (shoot number, colour intensity and growth vigor) but using any of those vitamins alone at 0.1mg/ L proved to be sufficient in increasing the shoot number and 0.1 or 0.5mg/ L enhanced both of colour intensity and growth vigor.