Dinamica di crescita e risposta produttiva di una coltura da biomassa lignocellulosica (Arundo donax L.) in tre ambienti del territorio campano

Le preoccupazioni per l’esaurimento delle risorse energetiche derivanti da energia fossile, hanno portato negli ultimi anni ad una maggiore attenzione verso fonti energetiche alternative rinnovabili, in particolare verso il settore agro energetico, il quale rappresenta un’ importante opportunità per lo sviluppo di riforme in campo sociale, ambientale ed economico. Inoltre, le filiere bioenergetiche offrono l’opportunità per compiere operazioni di tutela e valorizzazione ambientale, riducendo le emissioni di inquinanti atmosferici (con i conseguenti effetti positivi sul riscaldamento globale ed i cambiamenti climatici) seguendo di fatto gli indirizzi comunitari, e, contribuendo a risolvere il problema dell’approvvigionamento energetico, soprattutto nei i Paesi non energeticamente autosufficienti e indipendenti. Alcune bioenergie non pongono il problema della competizione tra uso alimentare ed energetico delle risorse agricole, essendo basate su sottoprodotti o scarti, ma addirittura consentono all’agricoltore di ricavarne un beneficio economico grazie ad una minore intermediazione del settore della trasformazione industriale (filiere corte). Possono essere economicamente valide anche a piccola scala, rendendosi particolarmente interessanti anche per sistemi agricoli di molte realtà italiane. Va inoltre ricordato che, anche la coltivazione di “colture dedicate” per le bioenergie possono avere ricadute positive sul territorio, se ben inserite, soprattutto nel caso in cui vengano utilizzati suoli poco adatti per la coltivazione di colture alimentari. Sulla base del crescente interesse verso la coltivazione di specie dedicate ad uso energetico, risulta importante testare anche sul territorio nazionale, il loro adattamento e le loro risposte produttive in ambienti di coltivazione non idonei alle colture alimentari. Per tali motivi, il presente lavoro si pone l’ obiettivo di studiare il comportamento dell’Arundo donax L., (specie erbacea perenne a destinazione energetica più promettente per l’areale mediterraneo) in aree considerate “marginali” del territorio campano, cioè caratterizzate da fattori ambientali limitanti (es. aree contaminate, presenza di falda affiorante, aree potenzialmente interessate alla progressiva salinizzazione, aree cerealicole collinari soggette ad erosione, ecc) che le rendono non idonee per le colture tradizionali o poco convenienti dal punto di vista economico. Per migliorare la conoscenza delle dinamiche di accumulo di biomassa, di sviluppo fogliare e delle asportazioni azotate durante il ciclo annuale e nel lungo periodo e comprendere le eventuali limitazioni di carattere ambientale e/o di tecnica colturale, è stata effettuata l’analisi di crescita che ha il vantaggio di utilizzare dati semplici primari in forma di aree, pesi e volumi al fine di studiare e descrivere i vari processi che coinvolgono lo sviluppo della coltura. I siti individuati ricadono in tre sistemi differenti del territorio campano, in particolare: pianura irrigua a rischio salinizzazione (sito di Bellizzi, SA), pianura a rischio inquinamento dei suoli (sito di Acerra, NA) e collina a rischio erosione (sito di Sant’Angelo dei Lombardi, AV). Le prove sono state condotte in tutti i siti in assenza d’irrigazione e con due tesi a confronto: (i) due livelli di concimazione azotata per la provincia di Salerno ed Avellino (50 kg ha-1 e 100 kg ha-1 di Azoto) e due livelli di fertilizzazione, con (20 t ha-1) e senza compost, per la provincia di Napoli. Le ricerche condotte hanno dato risposte produttive differenti riconducibili ai diversi trattamenti applicati in combinazione con differenti condizioni pedoclimatiche. Infatti, nel caso studio di Acerra, gli effetti del trattamento sono stati annullati dall’ elevata fertilità intrinseca del suolo. Per tutti i siti e tesi a confronto, lo sviluppo della biomassa aerea negli anni di coltivazione è risultata in accordo con quanto riportato in letteratura, ed in particolare sulla presenza di tre stadi di sviluppo della pianta, con il raggiungimento del plateau produttivo tra il 3° e 4° anno di crescita (Angelini et al. 2009). Le risposte produttive dei siti di Bellizzi (SA) e Sant’angelo dei Lombardi (AV), ambienti meno fertili rispetto al sito di Acerra, sono risultate in linea con quelle ottenute in Italia in suoli marginali da Nassi o di Nasso et al. (2010; 2013) ed inferiori a quelle riportate in letteratura per gli ambienti più fertili (Angelini et al., 2005a; Cosentino et al., 2006) le quali risultano in accordo con le produzioni ottenute nel sito di Acerra. Per quanto riguarda l’effetto dei diversi trattamenti a confronto, va detto che nel sito di Bellizzi con le tesi N100 ed N50 a confronto, nel lungo periodo il minor apporto di azoto al sistema da parte della concimazione (tesi N50) si traduce in un lento depauperamento delle riserve del suolo con un effetto riduttivo anche sulla biomassa prodotta, con una differenziazione sempre più evidente e marcata tra le due tesi nei diversi anni a confronto. Inoltre va sottolineato che nei due siti con le tesi (N100 e N50) a confronto (S.Angelo dei Lombardi e Bellizzi) la differenziazione in termini di biomassa aerea prodotta dalle tesi, è avvenuta dal terzo anno con un valore pressoché identico di differenza (circa il 16%). Diversamente nel sito di Acerra, le tesi a confronto: compost (COM) e no compost (NoCOM), hanno mostrato andamenti e produzioni simili senza diversificarsi. Tale comportamento è riconducibile alla qualità del suolo che ha ben supportato la crescita colturale. Nell’ambito della tesi realizzata, col fine di trasformare le informazioni raccolte in parametri di input per modelli di simulazione della produzione di biomassa aerea, basati sui modelli water growth engine, è stata determinata la water productivity (WP) dell’Arundo donax, non presente in letteratura, per le due tesi a confronto (N100 ed N50) del sito di Bellizzi per gli anni di monitoraggio (2012 e 2013). I valori ottenuti hanno confermato come questa coltura in presenza di limitato stress idrico e nutritivo mostri un comportamento a limite tra colture a ciclo fotosintetico C3 e C4 mostrando valori di WP vicini a 29 g m-2 (piante a ciclo C3 valori in letteratura tra 15-20 g m-2 e C4 tra 30-35 g m-2). Confermando le perplessità che si sollevano dai risultati ottenuti da Rossa et al., 1998 che mostravano un comportamento fotosintetico di tale specie (descritta come C3) superiore alle piante dotate di ciclo C4

Degradative actions of microbial xylanolytic activities on hemicelluloses from rhizome of Arundo donax.

Polysaccharidases from extremophiles are remarkable for specific action, resistance to different reaction conditions and other biotechnologically interesting features. In this article the action of crude extracts of thermophilic microorganisms (Thermotoga neapolitana, Geobacillus thermantarcticus and Thermoanaerobacterium thermostercoris) is studied using as substrate hemicellulose from one of the most interesting biomass crops, the giant reed (Arundo donax L.). This biomass can be cultivated without competition and a huge amount of rhizomes remains in the soil at the end of cropping cycle (10–15 years) representing a further source of useful molecules. Optimization of the procedure for preparation of the hemicellulose fraction from rhizomes of Arundo donax, is studied. Polysaccharidases from crude extracts of thermophilic microorganisms revealed to be suitable for total degradative action and/or production of small useful oligosaccharides from hemicelluloses from A. donax. Xylobiose and interesting tetra- and pentasaccharide are obtained by enzymatic action in different conditions. Convenient amount of raw material was processed per mg of crude enzymes. Raw hemicelluloses and pretreated material show antioxidant activity unlike isolated tetra- and pentasaccharide. The body of results suggest that rhizomes represent a useful raw material for the production of valuable industrial products, thus allowing to increase the economic efficiency of A. donax cultivation

Degradative actions of microbial xylanolytic activities on hemicelluloses from rhizome of Arundo donax

Polysaccharidases from extremophiles are remarkable for specific action, resistance to different reaction conditions and other biotechnologically interesting features. In this article the action of crude extracts of thermophilic microorganisms (Thermotoga neapolitana, Geobacillus thermantarcticus and Thermoanaerobacterium thermostercoris) is studied using as substrate hemicellulose from one of the most interesting biomass crops, the giant reed (Arundo donax L.). This biomass can be cultivated without competition and a huge amount of rhizomes remains in the soil at the end of cropping cycle (10–15 years) representing a further source of useful molecules. Optimization of the procedure for preparation of the hemicellulose fraction from rhizomes of Arundo donax, is studied. Polysaccharidases from crude extracts of thermophilic microorganisms revealed to be suitable for total degradative action and/or production of small useful oligosaccharides from hemicelluloses from A. donax. Xylobiose and interesting tetra- and pentasaccharide are obtained by enzymatic action in different conditions. Convenient amount of raw material was processed per mg of crude enzymes. Raw hemicelluloses and pretreated material show antioxidant activity unlike isolated tetra- and pentasaccharide. The body of results suggest that rhizomes represent a useful raw material for the production of valuable industrial products, thus allowing to increase the economic efficiency of A. donax cultivation

Lipid Production from Arundo Donax Grown under Different Agronomical Conditions

Hydrolysates of Giant reed (Arundo donax) biomass from three different agronomical conditions were used to grow the oleaginous yeast L. Starkey. The agronomical conditions affected the cellulose fraction of biomass, the amount of inhibitors generated during the acid hydrolysis, and the triglyceride yield after the yeast fermentation. Yet, the composition of triglycerides was not affected. Different approaches were developed to reduce the effect of inhibitors. The preliminary dilution of hydrolysates was studied, obtaining the highest values of biomass and lipid yields with a 50% dilution. Alternatively, the hydrolysates were pre-treated by adsorption and overliming. The latter pre-treatment gave the best results. A third approach was offered by the use of pre-adapted yeasts, that were able to grow in the presence of raw hydrolysates. The composition of the microbial triglycerides was compatible with the production of a biodiesel suitable for use as automotive fuel

Effects of urea-fertilization rates on the environmental performance of giant reed lignocellulosic feedstock produced for biorefinery purpose

A life cycle assessment (LCA) was carried out to investigate the environmental constrains of Arundo donax L. (common name giant reed) feedstock cultivation, for biorefinery purpose, treated with different amount of nitrogen fertilizations: 50 and 100 kg ha−1 of N as urea (low input- LI and high input- HI, respectively). The analysis was addressed for a cultivation of giant reed (GR) under Mediterranean conditions, considering primary data for the first eight years of cultivation and further modeled for the whole life cycle (15 years). The goals were, to ascertain and compare the environmental profile as well as to identify the hotspots for both investigated N- management techniques. Results highlighted a potential higher environmental performance for the LI giant reed cultivation, due to the reduced up-stream and direct field emissions linked to urea application. LI impacts resulted to be 24% lower than HI impacts, as averaged values for all impact categories. Crop yield represented a driving parameter and the lower biomass productivity under N low input management partially counteracted the entailed benefits of the lower fertilization rates. Through the inclusion of soil carbon storage, after seven years of harvesting, the whole crop phase revealed a net greenhouse gases sink and also differences between LI (−0.21 kg CO2 eq) and HI (−0.09 kg CO2 eq) appeared amplified. This was due to the enhanced C accumulation rate in LI trials (about 7.7 ton C ha−1 at the end of the seventh harvest year of GR cultivation), likely promoted by reduced soil organic matter mineralization at lower nitrogen availability. Nevertheless, in order to provide a full and comprehensive picture of the environmental performance of GR feedstock under different N-fertilization, further studies are needed encompassing the whole production chain: from the cultivation, through selected efficient conversion processes towards the co-production of added value products in the framework of the BioPoliS project

Lipids production by yeast grown on giant reed biomass

Giant Reed (Arundo Donax L.) is one of the most interesting crop for energy production due to the high productivity in less-fertile environments too. Among all the technological options, anaerobic fermentation with oleaginous yeasts for the synthesis of lipids rep- resents the last frontier of biological conversion of ligno-cellulosic biomasses to fuels or to bio-polymers. The chemical composition of biomass (i.e. cellulose, lignin and emicellulose) is a key factor of this process

Chemical composition and yield of rhizome biomass of Arundo donax L. grown for biorefinery in the Mediterranean environment

The contribution of the rhizome to productivity of fermentable sugars and the detailed composition of rhizomes were analyzed in three mature stands of Arundo donax L. cultivated in three locations of variable fertility in the South of Italy. Although the average yearly aboveground dry biomass and rhizome amount showed large and significant differences among sites, (15.3 and 2.6 Mg ha−1 year−1 of rhizomes in the most and less productive sites respectively), rhizomes of all sites had more than 30% of the dry matter (DM) as non-structural carbohydrates (NSC). Sucrose and starch were the most abundant NSC but measurable amounts of glucose, fructose, galactose and of the valuable trisaccharide raffinose were also present. The amount of NSC in rhizomes affected their content of dry mater, and water extractives. The ash content also varied significantly among cultivation sites; the highest amount was recorded in rhizomes of the most productive site (Acerra). The abundance in cell wall components of rhizomes was similar to that of published values for the above ground biomass. The present results demonstrate that NSC content in rhizomes of mature stands is a conserved trait. Hence, rhizome biomass, thanks to its quantity and high fermentable sugars content, should be considered as a relevant fraction of the A. donax crop product whose utilization can increase the productivity and the environmental fingerprint of this crop, in view of its biomass utilization in biorefinery

Biomass accumulation and heavy metal uptake of giant reed on polluted soil in southern Italy.

Giant Reed (Arundo donax L.) is well known for its adaptability to different ecological conditions, growing spontaneously in different regions of Southern Europe. Due to its high biomass productivity, it is commonly used for the production of energy, paper pulp, and wooden building materials (Papazoglou et al., 2005). Giant Reed could also be a useful tool for soil bioremediation thanks to its high resistance to pollutants (Papazoglou, 2006) together with a high accumulation capability of heavy metals in plant tissues (especially in rhizomes). A field trial was established in Acerra (Southern Italy, Campania) to asses the potential productivity of Giant Reed on a soil with high concentration of heavy metals. Treatments resulted from a factorial combination of two levels of compost (treated and non treated soil) and Trichoderma (inoculated and non inoculated rhizome). Soil samples were collected at twodepths (0-20 and 20-40 cm)at transplanting and at harvest. Soil and rhizosphere samples from plots under the different treatments were sampled and the composition of total aerobic bacteria, fungi, actinobacteria and microbial groups involved in key processes of the nitrogen cycle (e.g. aerobic free-living N2-fixing bacteria and ammonia-oxidizing bacteria) was estimated and the structure of cultivable populations was assessed. Plant aboveground tissues and rhizomes were collected after one growing season. A two-way ANOVA was performed on data considering compost addiction as main factor and Trichoderma inoculation as sub-factor in a split-plot design. Means were separated by LSD test according to a p-value of 0.05. Compost addiction allowed highest biomass production (13.2 Mg ha-1 vs 11.9 Mg ha-1 DMof non fertilized plots) and consequently highest metal uptakes. No interaction between factors was found. These results show the possibility of use Giant Reed for energy production on contaminated soils allowing incomes to farmers and reducing the levels of contamination