Drought Impact on the Morpho-Physiological Parameters of Perennial Rhizomatous Grasses in the Mediterranean Environment

The selection of non-food crops for bioenergy production in limiting environments is a priority for energy security and climate change mitigation. Therefore, more studies are needed on the interactions between species and environmental factors in specific sites which allows their selection for biomass production. The objective of this work is to study the impact of drought on the morpho-physiological parameters of perennial rhizomatous grasses Panicum virgatum L., Miscanthus × giganteus, and Arundo donax L. in the Mediterranean environment. Plants were grown on field and trials were carried out under support-irrigation and rainfed conditions during two consecutive years. Morpho-physiological parameters were measured in May, June and August, and dry biomass at the end of the experiment. Under rainfed conditions, A. donax presented the highest photosynthesis rate (25, 15 and 10 CO₂ m⁻² s⁻¹), relative water content (85–90%), and dry biomass (~4500 g plant⁻¹) compared with P. virgatum (20, 5 and 5 CO₂ m⁻² s⁻¹, 65–85% RWC and ~1400 g plant⁻¹) and Miscanthus (18, 4 and 0 CO₂ m⁻² s⁻¹, 80–10% RWC and ~260 g plant⁻¹). It is concluded that A. donax would be the best perennial rhizomatous grass to be used as bioenergy crop under Mediterranean conditions.