Yields and quality of Cynara cardunculus L. wild and cultivated cardoon genotypes. A case

study from a marginal land in Central Italy.

Rosa Francavigliaa*, Annarita Brunob, Margherita Falcuccia, Roberta Farinaa, Gianluca Renzia,

Donatella Esterina Russob, Lucia Sepeb, Ulderico Neria

a Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria, Centro di Ricerca per lo

Studio delle Relazioni tra Pianta e Suolo (CREA-RPS),Via della Navicella, 2-4, 00184 Roma, Italy

b Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria, Unità di Ricerca per la

Zootecnia Estensiva (CREA-ZOE), Via Appia, Bella Scalo, 85054 Muro Lucano, PZ, Italy

* Corresponding author: rosa.francaviglia@entecra.it (R.Francaviglia); phone +39 067005413; fax

+39 067005711

Keywords: cardoon, genotypes, yield, quality, Mediterranean crops.

Abstract

Cardoon yields and quality under low input conditions (reduced nitrogen fertilization and rainfed

conditions) in a marginal land of Central Italy are presented. During 2011-2013, two cultivated and

two wild cardoons were compared for the lignocellulosic biomass production, grain yield, and their

chemical composition. The results showed a 3-year average aboveground biomass and grain yield in

the range 8-18 and 1.2-2.8 t ha-1 dry matter respectively, significantly higher in the cultivated

genotypes. The grain lipid contents were not significantly different as average, but the wild

genotype Tolfa achieved the highest content (20.3%) in the last year of research. Average oil yields

were 0.45 and 0.23 t ha-1 in cultivated and wild genotypes respectively. ANOVA showed a general

prevalent influence of the genotype factor (G) on crop yields, and grain lipid and protein contents;

on the other hand, the nitrogen factor (N) never showed significant effects on the different

parameters. The chemical composition of the lignocellulosic biomass showed slight differences

among the genotypes, but not always significant. Cardoon cultivation improved soil fertility

parameters, even if differences were not always statistically different. Considering the results,

dedicated production chains could be implemented in many Italian Regions taking advantage also

from the availability of wild cardoon genotypes. The production costs and revenues analysis of

cardoon in comparison with other herbaceous annual crops, demonstrated the low cultivation costs

per hectare, the higher total revenues deriving from the yield outcomes, and its suitability for the

inclusion in arable cropping systems in marginal lands.

1. Introduction

Cynara is a relatively small genus of the Asteraceae family with very few perennial species, among

which the only having an economic interest is Cynara cardunculus L. which includes three taxa

(Foury, 1989; Rottenberg and Zohary, 1996; Raccuia and Melilli, 2007; Sonnante et al., 2007): wild

cardoon (Cynara cardunculus var. sylvestris Lam.), cultivated cardoon (Cynara cardunculus var.

altilis DC.), and globe artichoke (Cynara cardunculus subsp. scolymus Hegi). Recent studies

showed that wild cardoon is the ancestor of both the cultivated cardoon and globe artichoke

(Acquadro et al., 2005). The plant has its origins in the Mediterranean basin, and therefore is

particularly adapted to low rainfalls in summer, high rainfalls in autumn and winter months which

help the vegetative re-growth, mild winter temperatures and very warm conditions in summer.

The interest in the cultivation of cardoon arises from its perennial biological cycle, with a vegetative

growth in autumn-spring, i.e. the period with the highest natural water inputs from rainfall in

Mediterranean environments, while the seed ripening is in summer. This allows achieving high

yields without irrigation, while the root apparatus acts as a stock of reserve substances allowing the

vegetative re-growth in autumn after the summer dormancy.

Since simple cropping techniques and low production costs are among the requirements of energetic

crops, cardoon is cultivated in the Mediterranean areas of southern Europe given its adaptability to

semi-arid conditions, the high yields of lignocellulosic biomass, and other important uses (e.g. oil

from the seeds, inulin from the roots, etc.).

The lignocellulosic biomass is particularly suited for energy applications given its large scale

availability, the low cost of production and the low environmental input (Lynd et al., 2005). The

lignocellulosic biomass is having a growing importance in the production of bioethanol (Hahn-

Hägerdal et al., 2006; Prasad et al., 2007), even if there are still research challenges needing further

investigations about pre-treatment technologies and the optimization of production systems (Abelha

et al., 2013).

Many Authors have studied cardoon as source of lignocellulosic biomass for its use as solid fuel for

alternative energy production (Gonzáles et al., 2004a; Ochoa and Fandos, 2004), paper pulp

(Antunes et al., 2000; Gominho et al., 2001), production of biomass residues pellets for domestic

heating (Foti et al. 1999; Piscioneri et al. 2000; Gominho et al. 2001; Gonzáles et al., 2004b;

Fernandez et al., 2006; Raccuia et al., 2007).

Dry biomass yields are very variable in relation to the pedoclimatic conditions, the cropping

techniques and the genotypes compared. Available studies are mainly from Italy, Portugal and

Spain, and report dry biomass yield ranging from 10-15 to 30 t ha -1 due to differences in irrigation

inputs and fertilizer applications (Foti et al., 1999; Piscioneri et al., 2000; Gonzáles et al., 2004a;

Mauromicale and Ierna, 2004; Ochoa et al., 2004; Raccuia and Melilli, 2007; Ciancolini et al.,

2013; Gominho et al., 2014).

Besides biomass, cardoon provides a good production of seeds which can be used for oil production

suitable for human consumption, since this genus is botanically related to other oil crops (e.g.

sunflower), and the quality of the extracted oil is very similar (Maccarone et al., 1999; Curt et al.,

2002; Raccuia and Melilli, 2007; Curt et al., 2014). Seed yields and oil contents are very variable

and depend again on the genotype, the pedoclimatic conditions and the cropping techniques (Foti et

al., 1999; Curt et al., 2002; Raccuia and Melilli, 2007).

The extracted oil can be used also either pure as additive to the traditional fuels or treated with

different technologies for the production of biodiesel (Encinar et al., 1999; Encinar et al., 2002a, b;

Lapuerta et al., 2005).

Due to high protein content, the residual flour can be used for animal feed after oil extraction from

grain (Fernández and Manzanares, 1990; Foti et al., 1999). Fresh biomass is suitable to be used as

winter forage for livestock feeding (Cravero et al., 2012).

Roots can be used for extraction of inulin, of interest for food and no-food applications (Ritsema

and Smeekens, 2003; Raccuia and Melilli, 2004; Raccuia et al., 2005; Raccuia and Melilli, 2010).

Leaves are used because of the pharmacological and cosmetic properties of the polyphenolic

component (Perez-Garcia et al., 2000; Lupo, 2001; Jimenez-Escrig et al., 2003; Peschel et al., 2006;

Ramos et al., 2013).

The aims of this work were: i) to evaluate the yield potential of two cultivated genotypes in

comparison with two wild cardoon genotypes, ii) to evaluate the quality of the lignocellulosic

biomass (e.g. fibres) and grain (lipids and proteins), iii) to assess the possible effect of nitrogen

inputs under rainfed conditions, and iv) to compare the cardoon production costs and revenues with

other annual herbaceous crops.

2. Materials and methods

2.1 Study area

The field experiment was carried out in a marginal area of the hills of Latium Region (Central Italy)

at the CREA-RPS research farm of Tor Mancina near Rome (lat. 42°06’ N, long. 12°40’ E, alt. 43

m a.s.l.) during a 3-year period (2011-2013). Soils were Eutric Cambisols (WRB, 2014) of volcanic

origin with the following main physical and chemical soil properties in the top 40 cm determined in

winter 2010: sand 20%, silt 48%, clay 31%, silty-clay loam texture, field capacity 30.6% w/w,

wilting point 22.1% w/w, organic carbon 0.81%, total nitrogen 0.105%, C:N ratio 7.7, pH 6.7,

electric conductivity 134 μS cm-1, cation exchange capacity 28 cmol(+) kg-1, Ca2+ 19.6 cmol(+) kg-1,

available P 7.5 mg kg-1, exchangeable K 118 mg kg-1.

The long term mean climate (Fig. 1) has a mean annual temperature of 15.2°C (24°C in July-

August, 7°C in January), and 800 mm total rainfall (28 mm minimum in July). According to the

updated Köppen-Geiger climate classification (Kottek el al., 2006), the climate is warm temperate

with hot summers (Cfa). During 2011, total rainfall (572 mm) was much lower in comparison with

the long-term value, and was coupled with temperature peaks, mainly in July. In 2012, total rainfall

was 713 mm of which 421 mm from September to December, with a long dry period in June and

July; temperature was higher in comparison with the long-term values in the period June-August. In

2013, total rainfall was considerably higher than the mean value (1130 mm), particularly in the

spring, summer and winter months.

2.2 Experiment set-up and crop management

The potential of cultivated (Cynara cardunculus L. var. altilis DC) and wild (Cynara cardunculus

L. var. sylvestris Lam) cardoon genotypes was studied, both in terms of yields and quality of the

lignocellulosic biomass and seeds. Four genotypes were compared: two cultivated genotypes

(CDL07 and Gigante) and two wild cardoons, one from Sicily (RCT10) and the other from Latium

(Tolfa Mountains).

The initial experimental set-up followed a split-plot scheme with 3 replicates (plot size 28 m2,

seeding density 8 plants m-2), where the crop genotype was the main factor (plots 1-12 in Fig. 2). A

nursery was arranged for seeds germination to provide the seedlings for transplanting in October,

and again in November 2010 due to the low seeds germination in the previous nursery. As a

consequence, transplanting was made in January (first period) and February 2011 (second period),

and the second factor in the first year was therefore represented by the transplanting period (sub

plots TP1, TP2 in Fig. 2). A small amount of supplementary irrigation was provided locally after

transplanting. In the second year, nitrogen fertilization was added as third factor (0-50 kg N ha -1

from urea) following a split-split-plot scheme (sub-sub plots N0, N50 in Fig. 2), with a total of 48

sub-sub plots.

Seed-bed was prepared in October 2010 with a mechanical spade at 25 cm, and 300 kg ha -1 of triple

superphosphate (P2O5 46%) were distributed. Harrowing to control weeds was made in January

2011 before the transplanting. Urea was applied in November 2011 and 2012 at the dose of 50 kg

ha-1 in the N50 sub-sub plots.

Yearly samplings on each sub-sub plot (4 plants) were taken in August to determine either the yield

parameters (fresh and dry biomass, grain weight), and the qualitative parameters of biomass and

grain.

2.3 Chemical analyses

Soil chemical parameters were determined according to the standard methods (SSSA, 1986; SSSA,

1996; MiPA, 1997; MiPAF, 2000). Before the analysis, soil samples were air dried and sieved at 2

mm. pH and electric conductivity (ECe) were determined in a 1:2 soil:water suspension by

potentiometric method, particle size distribution with the wet sieving and sedimentation procedure,

texture according to USDA, field capacity and wilting point with a Richard apparatus (Soilmoisture

Equipment Corp., Santa Barbara, CA, USA), total N with the Kjeldahl method, organic carbon C by

dry combustion with a Carbon Analyzer RC612 (LECO Corporation, St. Joseph, MI, USA), cation

exchange capacity (CEC) and exchangeable cations with the barium chloride-triethanolamine

method of Mehlich buffered at pH 8.2., available P2O5 with the Olsen method.

Ash, crude fibre (CF), neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent

lignin (ADL) were analyzed according to the standard procedure of the AOAC (1990) on ground

dry plant samples sieved at 2 mm.

Crude fibre (CF) analysis was carried out following the Weende method by treating the samples

with a boiling solution of sulphuric acid 0.26 N and then of sodium hydroxide 0.31 N.

Subsequently, the samples residues were dried and incinerated.

Neutral deterged fibre (NDF), acid deterged fibre (ADF) and acid deterged lignin (ADL) analyses

were carried out with procedure of Van Soest et al. (1991).

The neutral deterged fibre (NDF) determines the content of the fibrous constituents of the cell wall

(cellulose, hemicelluloses, lignin, cutin, and mineral constituents). Its content was determined by

treating an aliquot of each sample for one hour with a boiling solution containing a neutral detergent

(sodium lauryl sulphate), and with subsequent drying and incineration of the sample residues.

The Acid deterged fibre (ADF) is used to determine the fibrous residue that is cellulose, lignin,

cutin and silica. Its content was determined by treating an aliquot of each sample for one hour with

a boiling solution containing the detergent cetyl-trimethyl ammonium bromide in sulphuric acid 1

N, and subsequent drying of the sample residues. The difference between NDF and ADF allows to

obtain an estimate of the content of hemicelluloses of the sample.

Acid deterged lignin (ADL) was determined by cold treating the residue ADF with sulphuric acid at

72% for three hours. Subsequently, the sample residues were dried and incinerated. Acid deterged

lignin (ADL) determines the lignin content of the sample, and the difference between ADF and

ADL determines the cellulose content in the sample. The crude fibre (CF), neutral deterged fibre

(NDF), acid deterged fibre (ADF) and acid deterged lignin (ADL) were analyzed with an Ankom

200 Fibre Analyzer (ANKOM Technology Corporation, Macedon, NY, USA).

The total lipid content of grain samples was measured with the Soxhlet method AOAC (1990),

using petroleum ether as organic extraction solvent and a Soxhtraction device (VWR International

PBI S.r.l, Milano, Italy). Grain protein content was measured using the Kjeldhal method (protein =

N x 6.25).

2.4 Cultivation costs and revenues

The cultivation costs of cardoon were compared with other crops commonly grown in the area, i.e.

durum wheat, sunflower and rapeseed The costs per hectare were derived considering the

machinery interventions commonly adopted in the area, based on the mean charges applied in 2012

by the farm contractors in the area of Rome and Rieti (Latium), and the local market costs of seeds,

fertilizers and pesticides. Economic revenues were derived from the total dry biomass yields

presented in this study for cardoon, and from the yields commonly obtained in the same area for

durum wheat, sunflower and rapeseed. Total dry biomass yield for cardoon was considered,

assuming the use of above-ground biomass for combustion, grain yield was considered for wheat,

sunflower and rapeseed. Yield prices were derived from Bezzi et al. (2006) for cardoon, and from

ISMEA (Istituto di Servizi per il MErcato agricolo Alimentare, http://www.ismea.it) for the other

herbaceous crops. Yield outcomes were calculated multiplying dry matter yields by yield prices.

The amortisation of the establishment costs for cardoon was also considered, assuming five years as

expected lifetime of the crop, and considering one fifth of the establishment costs. Total revenues

for all crops were calculated as difference between yield outcomes and yearly costs.

2.5 Statistical analyses

Chi-Square test was used to check normality of data distribution, and Levene’s test to check

homogeneity of variances; logarithmic transformation of data, before ANOVA, was used when

necessary (untransformed data are reported and discussed). Differences among treatments were

determined by analysis of variance (ANOVA), related to the experimental design adopted in the

field (split-plot design in 2011 and split-split-plot design in 2012 and 2013). The year effect was

tested in the ANOVA, and analyzed as further subplot in a split-split-split plot design, according

with some Authors that suggest this approach for perennial crops (Petersen, 1994).

General Linear Model procedure of the Statistica 8.0 software package (Statsoft, Tulsa, USA) was

used to perform the ANOVA, considering the block as random factor to calculate appropriate error

terms for the F test. Additionally, multiple means comparisons were performed through Fisher’s

protected least significant difference test (LSD test), at least for P ≤ 0.05.

3. Results and discussion

3.1 ANOVA results

Results of the analysis of variance for most parameters showed significant differences mainly

among genotypes (Tables 1-3). The genotype factor (G) showed a general prevalent influence on

yields during the three years of research, and the nitrogen factor (N) never showed significant

effects. The transplanting factor (TP), introduced in the experimental design due to problems in the

seed germination and maintained in the statistical analyses to detect the possible variance induced,

showed significant yield differences in the years with lower yields (2011 and 2013). 2012 showed

the higher yields, which were significantly influenced by the G factor only. The interactions of the

three factors (GxTP, GxN, and TPxN) never showed significant effects during the experiment

(Table 1).

The grain lipid content was significantly influenced by the interaction “year x genotype” (P =

0.0015). The other factors (TP, N) and their interactions were never significant with the F test. The

grain protein content was significantly influenced by the year and the genotype (Table 1).

The biomass quality (Tables 2-3) was generally not statistically influenced by the studied factors in

the majority of the analytical parameters (ash, crude fibre, hemicellulose, cellulose and lignin

contents). The most notable significant effect was shown by the genotype factor on the stem and

leaves hemicellulose content in 2012, and the genotype, nitrogen and their interactions on the lignin

content in leaves in 2013.

3.2 Biomass and grain yield

Yield parameters, even if statistically evaluated, were not economically significant in the first year,

that can be considered as a stabilization stage (Angelini et al., 2009); moreover low rainfall and

high temperatures in 2011 may have determined the low productivity. Cultivated genotypes showed

as average higher yields in comparison with the wild types in the second and third year, in terms of

fresh biomass, dry biomass, and grain weight, while the two nitrogen treatments (N0 and N50) had

no influence as shown in the ANOVA results. The main productive results are shown in Table 4.

The highest total fresh biomass yields were obtained with the Gigante genotype, with a 3-year

average value equal to 27.57 t ha-1 statistically significant in comparison with the other genotypes;

the maximum yield was obtained in 2012. The CDL07 genotype showed a fresh biomass yield

comparable to the yield obtained with Gigante in 2012, but with a sharp decrease in 2013 which

resulted in a 3-year average value of 19.22 t ha-1. The wild genotypes RCT10 and Tolfa showed

lower fresh biomass yields, equal to 3-year average values of 9.28 and 13.22 t ha-1 respectively.

Again, 2012 was the year with the highest yields for these genotypes. Overall, wild genotypes were

less productive than cultivated genotypes in terms of fresh biomass (mean yield ratio was 48%), and

the cultivated genotype Gigante showed more stable yields in the second and third year of the

experiment.

The trend of the total dry biomass yields was similar to the trend of the fresh yields, even if with

lower differences between cultivated and wild genotypes which are due to the lower moisture

content in the wild genotypes at harvest time, that can be ascribed to their early ripening. The

cultivated genotypes showed the highest dry biomass yields (16.0 t ha-1 as average) in comparison

with the wild genotypes (9.7 t ha-1 as average), and mean yield ratio was 60%.

CDL07 genotype showed the highest grain yields, with a 2-year average of 2.75 t ha-1 and the

maximum in 2012 (3.69 t ha-1). These yields were not significantly different in comparison with the

Gigante genotype (2.66 t ha-1). The wild genotypes showed a significantly lower grain yield, 1.21

and 1.79 t ha-1 in RCT10 and Tolfa respectively, with a mean yield ratio equal to 55% in

comparison with the cultivated genotypes.

Biomass yield results were generally in good agreement with the scientific literature available from

other Mediterranean countries. In a study performed in the Catania Plain (Sicily, southern Italy)

with a low irrigation input (100 mm), Foti et al. (1999) reported about 30.5 t ha -1 in cultivated

cardoon, 18.8 t ha-1 in wild cardoon as 3-year average dry biomass value. Lower yields but in

rainfed conditions were obtained in Basilicata (Piscioneri et al., 2000) with dry biomass yields for

cultivated cardoon genotypes ranging from 10 to 15 t ha-1 during the third year of cultivation. The

latter results were in agreement with the dry biomass yields obtained in Spain (Gonzales et al.,

2004a; Ochoa et al., 2004), but were lower than the yield of cultivated cardoon, equal to 20.6 t ha -1

as a 4-year average, reported by Mauromicale and Ierna (2004) in Sicily, with a very low irrigation

input (50 mm). Raccuia and Melilli (2007) reported a 3-year average dry biomass values in Sicily of

12.2 and 23.0 t ha-1 for wild and cultivated cardoon respectively, and with 50 mm irrigation. In a

large scale field experiment in Portugal, Gominho et al. (2014) reported a total dry biomass yield of

9.7 t ha-1, with minimum and maximum yields equal to 4.4 and 18.4 t ha-1 respectively due the

heterogeneity of the plant coverage in the field. Vasilakoglou and Dhima (2014) reported

total dry biomass yields equal to 11.0 and 21.8 t ha-1 in Northern and Central Greece

respectively, as 3-year averages of two irrigation treatments (0-90 mm) and with the application of

50 kg N ha-1 at the beginning of the experiment.

Dry matter grain yields commonly range from 1.3 t ha–1 (Curt et al., 2002) to 2.6 t ha–1 (Foti et al.,

1999), and up to 3.0 t ha–1 (Raccuia and Melilli, 2007). Grain yields reported by Gominho et al.

(2014) in Portugal were 2.2 t ha–1 as average (range 0.5-3.4 t ha–1). Vasilakoglou and Dhima

(2014) measured grain yields equal to 1.3 and 2.2 t ha-1 in Northern and Central

Greece respectively.

3.3 Grain and biomass quality

Lipid and protein contents in the grain are shown in Table 5. The cultivated genotypes showed

fairly constant lipid contents in 2012 and 2013, with average values of 18.5%. The wild genotypes

have shown instead contrasting results. Tolfa has shown the lowest value in 2012 (14.5%) and the

highest in 2013 (20.3%), while RCT10 showed good contents in 2012 (17.6%) and the lowest in

2013 (15.9%). Overall, lipid contents were not significantly different as average values in the four

studied genotypes. Moreover, oil yields were derived considering the grain lipid contents in % were

0.45 t ha-1 for both cultivated genotypes, and 0.23 t ha-1 as average value for wild cardoons (0.18

and 0.28 t ha-1 for RCT10 and Tolfa respectively).

The average protein content was higher in 2012 in comparison with 2013 (18.57% and 16.02%

respectively). Among the genotypes, CDL07 showed the highest protein content (18.0%), not

significantly different in comparison with Gigante (17.5%); RCT10 showed an intermediate content

(17.2%), significantly different in comparison with Tolfa (16.5%). Tolfa and CDL07 genotypes

were also significantly different. For both lipid and protein contents ANOVA showed a prevailing

significant effect of the genotypes, and nitrogen treatments (N0 and N50) had no effects also in this

case. The available literature reported grain lipid and protein contents in the range 20-23 and 19-

22% respectively in the Italian environments (Foti et al., 1999; Raccuia and Melilli, 2007).

Assuming a 24% of oil content, Gominho et al. (2014) reported an average oil yield in Portugal,

equal to 0.54 t ha-1 (range 0.12-0.81 t ha-1). With about 25% oil content, Vasilakoglou and Dhima

(2014) calculated an oil production of 0.28-0.40 and 0.49-0.66 t ha-1 in Northern

and Central Greece respectively.

The biomass quality in relation to ash, crude fibre, hemicellulose, cellulose and lignin contents is

reported in Table 6. Average ash content was higher in the leaves (15.1%) in comparison with the

stems (6.4%), crude fibre was higher in the stems (53.8%) than in the leaves (25.1%).

Hemicellulose was 6.4% in the leaves and 19.9% in the stems, cellulose 32.0% in the leaves and

50.2% in the stems, lignin 10.6% in the leaves and 11.5% in the stems. Ash, crude fibre and

hemicellulose did not show significant differences among the genotypes and the nitrogen treatments

(N0 and N50) as average, both in leaves and stems as already shown by the ANOVA. Cellulose

content in stems was significantly different in CDL07 (51.1%) and RCT10 (51.8%) in comparison

with Gigante (49.6%) and Tolfa (48.4%). Lignin content in stems was significant higher in Gigante

(13.4%) in comparison with CDL07 (11.3%), RCT10 (10.2%) and Tolfa (11.1%). ANOVA showed

a significant effect of genotype and nitrogen treatments only for lignin in leaves in 2013. Results

were in good agreement with Fernández et al. (2005), reporting the following composition of the

cardoon lignocellulosic biomass: 20-24% hemicellulose, 45-50% cellulose, and 7-14% lignin.

Lourenço et al. (2015) reported higher lignin contents in the range 18.8-25.5%.

3.4 Soil fertility

Soil fertility parameters before and after the three years of the experiment are shown in Table 7.

Available P significantly increased both in the topsoil (+63%, +4.8 mg kg -1) and in the subsoil

(+21%, +1.6 mg kg-1) due to residual effect of the initial fertilisation. Total N did not show

significant changes, but had a small increase in the topsoil (+2%, +0.002%) and an equivalent

decrease in the subsoil (-2%, -0.002%). Organic carbon did not show significant changes, but

increased in the topsoil (+13%, +0.10%) and in the subsoil (+4%, +0.03) The C/N ratio showed the

same trend of organic carbon, with an increase in the topsoil (+12%, +0.9) and in the subsoil (+5,

+0.4). The increase of soil organic carbon can be due to the leaves detachment during the harvest

and to the deep root system that produce high below-ground biomass. Moreover, deep roots are able

to extract nutrient elements and return them to the topsoil as root residue biomass. In a low quality

soil of Sicily (Mauromicale et al., 2014), the long-period cultivation of domestic and wild cardoon

(seven years) improved the soil fertility characteristics by increasing organic matter (+6.5%), total

nitrogen (+15.5%), and available phosphorus content (+15.8%).

3.5 Cultivation costs and revenues

The cultivation costs per hectare of cardoon, durum wheat, sunflower and rapeseed are shown in

Table 8 were all prices are VAT excluded (VAT, Value Added Tax, is a tax on the purchase price).

The main advantage of cardoon in comparison with the other herbaceous crops considered is the

multiannual growth, which allows the amortisation of the establishment and management costs

along the time span of the crop. Moreover, cardoon cultivation can be easily included in arable

farms with traditional cereal-fodder cropping systems particularly in marginal areas (low fertility,

climatic constraints, limited water availability, etc.), since no particular structural investments are

required. More in detail, the establishment costs of cardoon were lower in comparison with the

other crops considered but the possibility not to achieve an economically significant yield in the

first year must be considered, as previously stated. Among the establishment costs of cardoon, the

high costs related to the certified seeds (€ 207) of the cultivated genotypes must be pointed out; on

the other hand, an economically convenient seed reproduction of wild genotypes in the farm can be

hypothesized, after the mass harvesting in selected areas. In the following years costs were about

the half of the establishment of the annual herbaceous crop, and were mainly related to the harvest

operations, which can differ depending on the final use of the crop (above-ground biomass harvest

for combustion, or grain harvest for biodiesel production with threshing and subsequent harvesting

of stems with a mower-shredder-loader).

The economic budget of the four crops is shown in Table 9. Yield outcomes were 504 and 832 € ha -

1 for wild and cultivated cardoon genotypes respectively, and in the range 735-796 € ha -1 for wheat,

sunflower and rapeseed. Total revenues, calculated by the difference between yield outcomes and

the yearly costs already shown in Table 8, were higher and positive for cardoon (79 and 230 € ha -1

for wild and cultivated cardoons respectively), always negative for wheat and sunflower, and

positive for rapeseed due to the minimum tillage for the seedbed preparation.

4. Conclusions

ANOVA showed a general prevalent influence of the genotype factor (G) on crop yields, and grain

lipid and protein contents; on the other hand, the nitrogen factor (N) never showed significant

effects on the different parameters. The chemical composition of the lignocellulosic biomass

showed slight differences among the genotypes, which were mostly not significant.

In detail, wild genotypes were less productive than cultivated genotypes in terms of fresh and dry

biomass with a mean yield ratio between wild and cultivated cardoons equal to 48 and 60%

respectively. Similarly, grain weight was significantly higher in the cultivated genotypes in

comparison with the wild species, with a mean yield ratio equal to 55%.

Grain lipid contents were not significantly different as mean value, but the wild genotype Tolfa

achieved the highest content in the last year of research (about 20%); mean oil yields were higher in

the cultivated genotypes in comparison with the wild cardoons (mean yield ratio was 51%).

The biomass quality (ash, crude fibre, hemicellulose, cellulose and lignin) was not generally

influenced by the studied factors, but the lignocellulosic contents represented by hemicellulose,

cellulose and lignin were suitable for energy or paper pulp production.

In conclusion, cardoon has proved suitable for the cultivation in marginal lands like the hilly area of

Latium, helping to reduce the management inputs (nitrogen fertilization and irrigation supplies), to

maintain soil fertility, and to preserve the sustainability of the agricultural activity. Considering the

widespread diffusion of wild cardoon genotypes in many Italian Regions, small or associated

farmers, sectorial and processing industries, and land planning advisory boards could take

advantage also from the agricultural use of local cardoon genotypes for different bioenergy

purposes, through the implementation of dedicated production chains.

The production costs and revenues analysis of cardoon in comparison with other herbaceous annual

crops, demonstrated the low cultivation costs per hectare which can be amortised along the time

span of the crop, the higher total revenues deriving from the yield outcomes, and its suitability for

the inclusion in arable cropping systems in marginal lands, since no particular structural

investments are required to include the crop in the arable cropping systems.

Acknowledgements

The research is part of the BIOSEGEN Project (BIOcarburanti di SEconda GENerazione), funded

by the Italian Ministry of Agricultural Food and Forestry Policies (MiPAAF Decree

17532/7303/10), and coordinated by Dr. Vito Pignatelli, Italian National Agency for New

Technologies, Energy and Sustainable Economic Development (ENEA). We acknowledge the

contribution of CNR-ISAFOM (Istituto per i Sistemi Agricoli e Forestali del Mediterraneo), U.O.S.

Catania (Dr. Salvatore A. Raccuia) for providing the seeds of CDL07 and RCT10 genotypes and his

valuable suggestions during the research. We also acknowledge the technical contributions during

the research from Bruno Pennelli and Giampiero Simonetti (CREA-RPS). The valuable comments

of two anonymous reviewers are also acknowledged.

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0

5

10

15

20

25

30

35

0

50

100

150

200

250

J F M A M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D

Tem

pera

ture

°C

Rain

fall

mm

2011 2012 2013

R R mean T T mean

Fig. 1. Yearly climate (2011-2013) and long term mean values in the study area.

Fig. 2. Experimental design. Numbers represents the four genotypes with three replicates each

(plots 1-12). The gray arrows represent sub plots Transplanting Period (TP1 and TP2). The white

areas sub-sub plots N0, the dotted areas sub-sub plots N50.

Table 1ANOVA results: Probability level (P) of F test for yield and grain quality parameters during the 3 years of cultivation. Factors: genotype (G), transplanting period (TP), nitrogen (N).

Parameter2011 2012 2013

G TP GxTP G TP N GxT

P GxN TPxN G TP N GxTP GxN TPxN

Biomass yield(t ha-1 DM) ns 0.0134 ns 0.0318 ns ns ns ns ns 0.022

6 0.0144 ns ns ns ns

Biomass yield(t ha-1 FM) 0.00035 ns ns 0.0339 ns ns ns ns ns 0.001

3 0.0095 ns ns ns ns

Grain yield(t ha-1) - - - 0.0476 ns ns ns ns ns 0.0

079 0.0263 ns ns ns ns

Grain lipid content(% DM)

- - - 0.0015 ns ns ns ns ns 0.0289 ns ns ns ns ns

Grain protein content (% DM) - - - 0.043 ns ns ns ns ns ns ns ns ns ns ns

ns = P>0.05.

Table 2ANOVA results: Probability level (P) of F test for chemical parameters of stems during the 2 years of cultivation. Factors: genotype (G), transplanting period (TP), nitrogen (N).

Parameter2012 2013

G TP N GxTP

GxN

TPxN G T

P N GxTP

GxN

TPxN

Ash ns 0.009

ns ns ns ns n

s ns ns ns ns ns

Crude fibre ns 0.048

ns ns ns ns n

s ns ns ns ns ns

Hemicellulose

0.037 ns n

s ns ns ns ns ns n

s ns ns ns

Cellulose ns ns ns ns ns ns

ns

nsns ns ns ns

Lignin ns ns ns ns ns ns n

s ns ns ns ns ns

ns = P>0.05.

25

Table 3ANOVA results: Probability level (P) of F test for chemical parameters of leaves during the 2 years of cultivation. Factors: genotype (G), transplanting period (TP), nitrogen (N).

Parameters2012* 2013

G TP N GxTP GxN TPxN G TP N GxT

P GxN TPxN

Ash ns ns ns ns ns 0.037 ns ns ns ns ns nsCrude fibre ns ns ns ns ns ns ns ns ns ns ns ns

Hemicellulose 0.032 ns ns ns ns ns ns ns ns ns ns ns

Cellulose ns ns ns ns ns ns ns ns ns ns ns nsLignin ns ns ns ns ns ns 0.011 ns 0.011 ns 0.035 ns* Only two genotypes (Gigante, CDL07); ns = P>0.05.

26

Table 4Fresh and dry matter biomass and grain yields in t ha-1 (±SD) during the experiment.

Total fresh biomass

Genotype 2011 2012 (ln) 2013 (ln) Mean * (ln)

CDL07 3.64±1.15 a 34.13±11.62 b 19.90±4.71 b 19.22±5.83 b

Gigante 6.69±1.10 b 38.38±13.29 b 37.63±10.56 c 27.57±8.31 c

RCT10 2.49±0.85 a 15.33±4.18 a 10.02±3.90 a 9.28±2.98 a

Tolfa 3.01±0.92 a 21.33±5.27 a 15.31±9.96 ab 13.22±5.38 ab

Total dry biomass

Genotype 2011 2012 (ln) 2013 (ln) Mean *

CDL07 1.05±0.36 ns 28.14±9.10b 13.87±2.75 b 14.35±4.07 bc

Gigante 2.42±1.01 ns 28.29±8.56 b 22.47±5.81 c 17.73±5.13 c

RCT10 1.18±0.53 ns 14.01±3.81 a 9.15±3.56 a 8.11±2.64 a

Tolfa 1.42±0.69 ns 18.43±4.91 a 13.86±9.01 ab 11.24±4.87 ab

Grain weight (11% moisture) §

Genotype 2011 2012 (ln) 2013 Mean

CDL07 - 3.69±1.01 c 1.81±0.43 b 2.75±0.72 c

Gigante - 3.48±1.40 bc 1.84±0.45 b 2.66±0.92 bc

RCT10 - 1.85±0.48 a 0.57±0.33 a 1.21±0.40 a

Tolfa - 2.40±0.61 ab 1.18±0.81 ab 1.79±0.71 ab(ln) logarithmic transformation before ANOVA; * ANOVA on averages of sub samples of main plots; § seed weight not determined in the first year due to the low amount of heads at harvesting; different letters within each column are significantly different at P<0.05 (LSD test); ns = not significant.

27

Table 5Lipid and protein contents of grain in % (±SD) during the experiment.

Genotype

Lipid Protein

2012 2013 Mean 2012 2013 Mean

CDL07 18.1±3.3 b 18.4±1.7 ab 18.2±3.3 ns 19.7±1.6 b 16.3±1.4 ns 18.0±2.3 c

Gigante 19.4±2.6 b 18.2±3.3 ab 18.8±3.0 ns 19.0±1.4 b 16.0±1.1 ns 17.5±2.0 bc

RCT10 17.6±3.1 b 15.9±3.5 a 16.7±2.6 ns 18.2±1.6 ab 16.2±1.5 ns 17.2±1.9 b

Tolfa 14.5±2.9 a 20.3±1.4 b 17.4±3.7 ns 17.4±1.2 a 15.6±1.2 ns 16.5±1.5 aDifferent letters within each column are significantly different at P<0.05 (LSD test); ns = not significant.

28

Table 6Ash, crude fibre, hemicellulose, cellulose and lignin contents (% d.w.) (±SD) during the experiment.

Ash

GenotypeLeaves Stems

2012 2013 Mean 2012 2013 Mean

CDL07 16.5±2.1 ns 13.1±1.6 ns 14.8±2.5 ns 6.4±1.0 ns 6.6±0.7 ns 6.5±0.8 ns

Gigante 14.5±1.1 ns 16.3±3.1 ns 15.4±2.4 ns 5.5±0.9 ns 6.6±0.6 ns 6.1±0.9 ns

RCT10 nd 15.1±10.8 ns - 6.3±1.5 ns 6.8±0.7 ns 6.5±1.2 ns

Tolfa nd 11.3±1.1 ns - 5.4±1.2 ns 7.1±1.3 ns 6.3±1.5 ns

Crude fibre

GenotypeLeaves Stems

2012 2013 Mean 2012 2013 Mean

CDL07 24.7±2.3 ns 27.6±6.6 ns 26.1±5.1 ns 53.5±2.8 ns 54.6±2.4 ns 54.1±2.6 ns

Gigante 26.1±3.6 ns 22.0±2.3 ns 24.1±3.6 ns 56.2±4.3 ns 52.9±1.8 ns 54.6±3.6 ns

RCT10 nd 28.7±3.5 ns - 55.9±2.3 ns 52.1±1.5 ns 54.0±2.7 ns

Tolfa nd 28.8±4.0 ns - 54.1±3.5 ns 50.7±3.1 ns 52.4±3.7 ns

Hemicellulose

GenotypeLeaves Stems

2012 2013 Mean 2012 2013 Mean

CDL07 11.3±3.4 a 4.6±2.6 ns 7.9±4.5 ns 19.1±1.4 ab 18.7±2.8 ns 18.9±2.2 ns

Gigante 7.0±3.7 b 2.5±1.8 ns 4.8±3.7 ns 18.4±1.1 a 19.3±3.1 ns 18.8±2.3 ns

RCT10 nd 2.6±1.3 ns - 21.3±2.1 bc 21.2±3.2 ns 21.2±2.6 ns

Tolfa nd 3.2±1.9 ns - 21.5±1.9 c 20.0±1.6 ns 20.8±1.9 ns

Cellulose

GenotypeLeaves Stems

2012 2013 Mean 2012 2013 Mean

CDL07 29.0±3.8 ns 34.3±5.1 ns 31.7±5.2 ns 51.7±2.3 ns 50.4±3.0 ns 51.1±2.7 b

Gigante 32.8±4.9 ns 31.6±2.6 ns 32.2±3.9 ns 50.8±3.0 ns 48.4±2.1 ns 49.6±2.8 ab

RCT10 nd 38.2±2.5 ns - 52.5±1.8 ns 51.1±2.8 ns 51.8±2.4 b

Tolfa nd 37.2±4.1 ns - 50.2±2.5 ns 46.6±2.9 ns 48.4±3.2 a

Lignin

GenotypeLeaves Stems

2012 2013 Mean 2012 2013 Mean

CDL07 8.7±0.9 ns 12.5±1.5 a 10.6±2.3 ns 10.7±1.3 ns 11.9±3.0 ns 11.3±2.3 a

Gigante 8.7±1.9 ns 12.3±1.6 a 10.5±2.5 ns 13.0±1.4 ns 13.7±1.7 ns 13.4±1.6 b

RCT10 nd 15.0±1.8 b - 10.6±1.7 ns 9.8±1.2 ns 10.2±1.5 a

Tolfa nd 14.8±2.1 b - 10.5±1.3 ns 11.8±1.4 ns 11.1±1.5 a

29

nd, no data due to the detachment of leaves before harvesting; different letters within each column are significantly different at P<0.05 (LSD test); ns = not significant.

30

Table 7Soil fertility parameters (average values of all plots).

Parameter Depth of sampling cm

2010(A)

2013(B) (B-A)/A*100

P mg kg-1

0-20 (topsoil) 7.6 a 12.3 b 63

20-40 (subsoil) 7.4 a 9.0 b 21

0-40 7.5 a 10.7 b 43

Total N %

0-20 (topsoil) 0.105 ns 0.107 ns 2

20-40 (subsoil) 0.104 ns 0.102 ns -2

0-40 0.105 ns 0.105 ns 0

Organic carbon %

0-20 (topsoil) 0.80 ns 0.90 ns 13

20-40 (subsoil) 0.81 ns 0.84 ns 4

0-40 0.81 ns 0.87 ns 7

C/N

0-20 (topsoil) 7.5 ns 8.4 ns 12

20-40 (subsoil) 7.8 ns 8.2 ns 5

0-40 7.7 ns 8.3 ns 8Different letters within each row are significantly different at P<0.05; ns = not significant.

31

Table 8Establishment costs (€), including crop management, materials and harvesting.

Costs Cardoon (first year) Durum wheat Sunflower Rapeseed **

Ploughing 117 (45-50 cm) 92 (< 40 cm) 117 (45-50 cm)

Pulling up 44 44 44

Harrowing 48 48 48 48

Harrowing 48

Fertilizer application (at sowing) 24 24 24 24

Nitrogen application (top dressing) 24 24 24

Seeding 40 40 40 40

Rolling 35 35

Temporary ditches (hilly areas) 30 (optional)

Herbicide spraying 32 (optional) 32 32 32

Pesticide spraying 32 (optional) 32 (optional) 32 (optional)

Threshing 109 109 109

Crop residues chopping 41 41 41

Sub Total 274-338 455-518 515 402-434

Certified seeds 207 * 120 50 80

Phosphoric fertilizer (300 kg ha-1) 132

NP fertilizer (at sowing) 120 120 120

Nitrogen fertilizer (top dressing) 94 94 94

Herbicides 15-85 § 31 39

Geo-pesticides 28

Pesticides 20 (optional) 40 (optional) 20 (optional)

Sub Total 339-359 349-474 323 333-353

Total establishment costs per hectare 613-697 804-992 838 735-787

Costs (second year onwards) Cardoon

Nitrogen fertilizer 24

Pesticide spraying 32 (optional)

Heads threshing 109 (optional)

Harvesting of total biomass 210

Sub Total 234-375

Pesticides 20 (optional)

Urea (150 kg ha-1) 68

Sub Total 68-88

Total yearly costs per hectare 302-463

32

* Wholesale price of Gigante variety applied by the S.A.I.S company: € 46.00/ kg (dose: 4.5 kg ha-1); ** seedbed preparation by minimum tillage (two harrowings) after wheat; § variable cost in relation to the weeds to be controlled.

33

Table 9Economic budget of the four crops.Economic budget terms Cardoon Wheat Sunflower Rapeseed

Dry matter yield t ha-1 † 9.7-16.0 ‡ 3.0 2.0 1.7Yield price € t-1 52 245 385 468

Yield outcome € ha-1 504-832 735 770 796

Establishment costs (amortization) € ha-1 123-139

Total revenues (yield outcomes-costs) € ha-1 79-230 -69 -257 -68 61-8† Total dry biomass yield for cardoon, grain yield for wheat, sunflower and rapeseed; ‡ wild and cultivated genotypes respectively.

34