Up-scaling agamic propagation of giant reed (Arundo donax L.) by means of single-node stem cuttings

Giant reed (Arundo donax L.) is a warm-season, fast growing lignocellulosic crop suitable to Mediterranean and semi-arid environments. However, its sterility limits a cost-effective propagation along with environmental impacts associated with rhizome processing. In the present study, the effects of intrinsic (node size and node chemical composition) and extrinsic factors (node pretreatment with growth regulators) on root and shoot development were investigated under different excision time of node-cuttings in a controlled and open field conditions. Results indicated that nutrients availability of the propagation material plays a key role in rooting development. To enhance the success of giant reed propagation by single node stem-cuttings, the best period for node excision is July in open field trial, followed by the late spring (May). Nodes whose diameter exceed 2 cm resulted in higher rooting and plantlets development even in the less favorable excision dates. However, when big nodes are adopted in controlled environments even winter periods are eligible, being particularly useful for spring open field transplants of rooted plantlets. Among the growth regulators used in the present study, indole- 3-butyric acid - IBA (in controlled environment) resulted effective in promoting rooting particularly in the worse excision date (April); in open field, IBA significantly improved rooting in the excision dates of February and May in the big nodes, and only in February in the small ones. NAA (1-naphthaleneacetic acid) was almost ineffective in enhancing rooting as compared to the control. The present study might open a new perspective to overcome one of the most significant drawbacks to establish giant reed, namely its agamic propagation.