Productivity of giant reed (Arundo donax L.) and miscanthus (Miscanthus x giganteus Greef et Deuter) as energy crops: growth analysis

The growing interest in bioenergy crops is leading to the development of new research aims. In fact, there is a lack of knowledge of most of these crops in terms of suitability to specific environmental conditions and of biotic and abiotic influences. The objective of our study was to compare giant reed (Arundo donax L.) and miscanthus (Miscanthus × giganteus Greef et Deuter), two promising lignocellulosic energy crops in Southern Europe, in terms of productivity, through growth analysis, in order to understand environmental and/or management constraints to crop development. Our research was carried out in 2009, in San Piero a Grado, Pisa (Central Italy; latitude 43°41’ N, longitude 10°21’ E), on a seven-year-old crop, in loam soil characterised by good nutrient and water availability. Results confirmed high yields in both species, about 40 t/ha/yr in miscanthus and 30 t/ha/yr in giant reed, achieved in the second half of October. Different growth strategies were noted as miscanthus developed a greater number of stems per square meter and higher stems, although it showed minor basal stem diameter and leaf area changes. In addition, the physiological difference between crop pathways (C3 in giant reed vs C4 in miscanthus) in a non-limiting environment allowed miscanthus to perform better. As a result, the choice of the proper crop has to be made in order to obtain maximum yield levels, minimising external inputs and optimising the land use.