Large-scale in vitro propagation of giant reed (Arundo donax L.), a promising biomass species

Giant reed (Arundo donax L.), a promising energy crop, is vegetatively-propagated from fragments of stems and rhizomes. This may limit large-scale cultivation, since it is time-consuming and involves considerable cost and effort. Tissue culture is an alternative to conventional methods of vegetative propagation and may represent a useful tool for large-scale propagation of plants for biomass production programmes. This report describes a protocol for the largescale in vitro propagation of giant reed by adventitious bud formation. Stem nodes with dormant buds proved to be the most effective to initiate in vitro cultures giving the highest percentage of differentiated shoots (77%) compared to the other plant fractions tested. A sterilisation procedure using 5 g l-1 HgCl2 enabled the production of sterile explants. Moreover, early results indicated that late Autumn excision dates not only gave a higher percentage of welldeveloped shoots ( > 80%), but also a lower level of bacterial contamination (15 - 20%). 6-Benzylaminopurine (BAP) at 3.0 mg l-1 was most effective in promoting shoot multiplication when added to a basal medium containing Murashige and Skoog (MS) macro- and micro-nutrients, Morel's vitamins, 30 g l-1 sucrose, and 7.0 g l-1 bacteriological agar supplemented with 1.0 mg l-1 indole-3-acetic acid (IAA) and 0.05 mg l-1 gibberellic acid (GA3). Rooting was successfully induced on the same basal medium used for proliferation, modified by halving the MS macro-nutrients and replacing BAP and the other growth regulators with 2.0 mg l-1 1-naphthaleneacetic acid (NAA). Successful acclimatisation (> 95% survival) of plantlets was carried out, even in late Winter, in a cold greenhouse or under simpler facilities such as shade nets.