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Great effort has been placed to identify the most suited bioenergy crop under different environments and management practices, however, there is still need to find new genetic resources for constrained areas. For instance, South Mediterranean area is strongly affected by prolonged drought, high vapour pressure deficit (VPD) and extremely high temperatures during summertime. In the present work we investigated the soil water effect on crop growth and leaf gas exchange of Saccharum spontaneum L. ssp. aegyptiacum (Willd.) Hackel, a perennial, rhizomatous, herbaceous grass. Furthermore, the net increase of biomass production per unit light intercepted [radiation use efficiency (RUE)] and per unit water transpired [water use efficiency (WUE)] was also studied. To this end a field trial was carried out imposing three levels of soil water availability (I100, I50 and I0, corresponding to 100%, 50% and 0% of ETm restutition) under a semi-arid Mediterranean environment. Leaf area index (LAI), stem height, biomass dry matter yield, CO2 assimilation rate, and transpiration rate resulted significantly affected by measurement time and irrigation treatment, with the highest values in I100 and the lowest in I0. RUE was the highest in I100 followed by I50 and I0; on the other hand, WUE was higher in I0 than I50 and I100. At LAI values greater than 2.0, 85% photosynthetically active radiation was intercepted by the Saccharum stand, irrespective of the irrigation treatment. Saccharum spontaneum spp. aegyptiacum is a potential species for biomass production in environment characterized by drought stress, high temperatures and high VPD, as those of Southern Europe and similar semi-arid areas. [ABSTRACT FROM AUTHOR]

Highlights • Propagation by single-node stem cutting of giant reed (Arundo donax) was attempted. • Nutrients availability on the node plays a key role in rooting development. • In open field, the best period for node excision is July followed by May. • Nodes whose diameter exceed 2 cm showed higher rooting and plantlets development. • IBA resulted effective in promoting rooting in the worst excision dates. Abstract 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. [ABSTRACT FROM AUTHOR]