IJA-2018_2.qxp_Hrev_master 06/06/18 12:44 Pagina 103 Italian Journal of Agronomy 2018; volume 13:937 Exploring the potential of wild perennial grasses as a biomass source in semi-arid Mediterranean environments Javier Gulías,1 Rita Melis,2 Danilo Scordia,3 Josep Cifre,1 Giorgio Testa,3 Salvatore L. Cosentino,3,4 Claudio Porqueddu2 1Research group on Plant Biology under Mediterranean Conditions, Department of Biology, University of the Balearic Islands, Palma de Mallorca, Spain; 2Institute for Animal Production System in Mediterranean Environment, National Research Council (CNR-ISPAAM), Sassari, Italy; 3Department of Agriculture, Food and Environment, University of Catania, Italy; 4Trees and Timber Institute, National Research Council (CNR-IVALSA), Catania, Italy tosynthesis was measured in the C4 species S. spontaneum and S. –2 –1 Abstract halepense (26.6 and 23.8 mmol CO2 m s , respectively). A. mau- ritanicus showed the lowest transpiration rate and the highest In Mediterranean environments, few perennial grass species –2 –1 instantaneous water use efficiency (2.7 mmol H2O m s and 6.9 are available for cultivation in rainfed systems and marginal lands, –1 mmol CO2 mmol H2O , respectively). S. spontaneum was the where plants with excellent adaptation are required. The aim of most productive species, yielding more than 18 Mg DM ha–1 as a the present work was to determine the potentiality of five native three-year average. The highest content of acid detergent lignin Mediterranean perennial grasses for lignocellulosic biomass pro- was found in P. miliaceum, while A. mauritanicus was the species duction. Wild accessions of three hemicryptophytes richest in hemicellulose and cellulose and poorest in ash. S. spon- (Ampelodesmos mauritanicus, Hyparrhenia hirta, and taneum showed the highestonly moisture content at harvest. Overall, Piptatherum miliaceum) and two geophytes (Saccharum sponta- the studied species showed interesting morphological, physiolog- neum ssp. aegyptiacum and Sorghum halepense) were collected at ical, productive and qualitative traits. Nevertheless, additional three Mediterranean sites (Sicily, Sardinia and Majorca), and their research is necessary to investigate their long-term performance morphological, physiological, productivity and quality traits were under differentuse management strategies. evaluated in the field. The species differed in height, with S. spon- taneum and A. mauritanicus being the tallest. The leaf mass ratio ranged from 0.23 to 1.0 g g–1 among species. Maximum net pho- Introduction The interest in producing biomass to generate bioenergy has Correspondence: Danilo Scordia, Department of Agriculture, Food and increased to a great extent during the last 20 years worldwide. Environment (Di3A), University of Catania, Via Valdisavoia 5, 95123, Different crops, such as corn and rapeseed, have been used for this Catania, Italy. purpose (Firrisa et al., 2013; Zentková and Cvengrošová, 2013; Tel.: +39.095.234.496 - Fax: +39.095.234.449. Karlen et al., 2014; Liu et al., 2014). However, the use of these E-mail: [email protected] crops as a biomass source has been criticised, since their use com- petes with food production in a direct or indirect way, increasing Key words: Bioenergy; multipurpose species; wild accessions; ligno- food prices and limiting the food supply in a food-limited world cellulose; low-input system; marginal lands. (Valentine et al., 2012; Hennecke and Rettenmaier, 2015). Due to this reason, second-generation biomass composed of inedible Acknowledgements: this work was funded by the European Union FP7 species has been suggested as an interesting alternative OPTIMA project Optimization of Perennial Grasses for Biomass Production (Grant Agreement Non-commercial289642). The authors gratefully (Sanderson and Adler, 2008; Simmons et al., 2008; Naik et al., acknowledge Mr. D. Dettori and Mr. D. Nieddu (CNR-ISPAAM), Mr. 2010). Several perennial grasses have been investigated as sec- S. Virgillito, Mr. G. Patanè and Mr. S. Calcagno (Di3A) for their tech- ond-generation feedstock candidates both for generating bioener- nical assistance in the field activities. gy (i.e., heat and energy, bio-oil, syngas, etc.) and as a source of structural carbohydrates for biofuel production. In fact, perennial Conference presentation: SIA XLV Congress, Sassari, 2016. grasses have the advantage of producing relatively larger amounts of biomass than most annual species, even under low-fertility con- Received for publication: 7 February 2017. ditions. In addition, crop management costs for perennial grasses Revision received: 24 October 2017. are much lower than those for annual species, since they are plant- Accepted for publication: 30 October 2017. ed only at the beginning of the establishment of a long-lasting stand and require lower agronomic inputs to sustain yields ©Copyright J. Gulías et al., 2018 Licensee PAGEPress, Italy (Zegada-Lizarazu et al., 2010). The benefit is reduced greenhouse Italian Journal of Agronomy 2018; 13:937 gas emissions (Rettenmaier et al., 2010). Recently, it has been doi:10.4081/ija.2018.937 suggested that these advanced biomass crops should be grown in marginal lands to avoid competition with food crops in arable This article is distributed under the terms of the Creative Commons lands (Kang et al., 2013). Switchgrass (Panicum virgatum L.), Attribution Noncommercial License (by-nc 4.0) which permits any non- miscanthus (Miscanthus spp.) and giant reed (Arundo donax L.) commercial use, distribution, and reproduction in any medium, provid- are some of the most investigated perennial grasses for producing ed the original author(s) and source are credited. second-generation bioethanol (Scordia et al., 2014), but in [Italian Journal of Agronomy 2018; 13:937] [page 103] IJA-2018_2.qxp_Hrev_master 06/06/18 12:44 Pagina 104 Article Mediterranean environments, some constraints, especially water and having a perennial habit, belong to two groups (Table 1): i) shortages during summer, often reduce the production of these hemicryptophytes [(smilo grass (Piptatherum miliaceum (L.) species to various extents (Cosentino et al., 2007, 2014). Under a Coss.), diss grass (Ampelodesmos mauritanicus (Poir.) Dur. & Mediterranean climate, characterised by 2-6 months of drought Schinz), and coolatai grass (Hyparrenia hirta (L.)]; and ii) geo- during summer and short dry periods occurring during the growth phyte rhizomatous [(African fodder cane (Saccharum spontaneum phase from autumn to spring, plant CO2 assimilation is limited to L. ssp. aegyptiacum Willd. Hackel) and Johnsongrass (Sorghum a great extent (Gulías et al., 2009). Moreover, more limiting sce- halepense (L.) Pers.)]. narios are forecasted due to climate change during the 21st century P. miliaceum was grown at the three sites (ssp. miliaceum in in the Mediterranean basin; even areas receiving more precipita- Sicily, Sardinia and Majorca and ssp. thomasii also in Majorca), A. tion may get drier than today due to increased evaporation and mauritanicus was grown in Sardinia and Majorca, and H. hirta, S. changes in the seasonal distribution of rainfall and its intensity, halepense and S. spontaneum were grown in Sicily. higher air temperatures and increased occurrence of extreme All experimental sites are characterised by a typical weather events (Giannakopoulos et al., 2009; Cosentino et al., Mediterranean climate with mild and wet winters and hot and dry 2012). For these reasons, high yields of conventional energy crops summers. The total annual rainfall, based on long-term observa- can be achieved in southern Europe only in arable lands under irri- tions (30 years), is 447, 550 and 450 mm in Catania (Sicily, Italy), gation (Cosentino et al., 2012). Sassari (Sardinia, Italy) and Palma (Palma de Majorca, Spain), Under rainfed conditions, plants with excellent adaptation are respectively. The mean maximum temperature of the warmest needed; hence, it would be worth focusing on perennial grass month and the mean minimum temperature of the coldest month species well suited for specific sites and with low demand for are 32.0ºC and 5.0ºC in Catania, 29.5ºC and 6.2ºC in Sassari, and inputs. 30.2ºC and 7.4ºC in Palma, respectively. Over the experimental Currently, there is remarkable and still widely unexplored period, main meteorological parameters, such as air temperature plant diversity in the Mediterranean basin. Tilman et al. (2006) and precipitation, were continuously measured near the experi- highlighted that wild populations might represent a potential mental fields at the three sites. source of biomass plants in agriculturally degraded lands due Plants were grown in onlyexperimental field plots under rainfed mainly to traits of resistance and phenotypic plasticity. However, conditions with the aim to evaluate the aboveground biomass knowledge regarding their ecology, biology, physiology and yield, physiological traits and biomass quality. agronomy must be prioritised before they can be recommended as At all sites, gas exchange parameters, plant height, leaf mass candidate crops (Scordia et al., 2017). ratio (LMR, leafuse biomass/shoot biomass), aboveground biomass The general objective of this work was to determine the poten- production and biomass quality were determined. tiality of five native Mediterranean perennial grasses (Piptatherum miliaceum ssp. miliaceum and ssp. thomasii, Ampelodesmos mau- Field trial management ritanicus, Saccharum spontaneum ssp. aegyptiacum, Sorghum Site 1: Sicily halepense and Hyparrenia hirta) as