Valorization of Citrus spp. Cultivars cultivated in Sicily for the industrial use of citrus derivatives and in particular for potential alternative uses of essential oils for the enhancement of the island's citrus production

[ES] En esta tesis doctoral se discuten una serie de cuestiones científicas relacionadas con a la producción y el procesamiento de algunas especies de cítricos de especial relevancia en Sicilia y en el área mediterránea. Los objetivos se centran en estudiar la trazabilidad y sostenibilidad de la producción de algunas especies de cítricos, así como encontrar nuevas aplicaciones a los subproductos y productos de desecho de la industria, con el fin de mejorar su rentabilidad. Por lo tanto, los temas que se desarrollarán serán los siguientes: caracterización de los compuestos bioactivos presentes en aceites esenciales y en el hidrolato de diferentes especies de cítricos; seguimiento del efecto del estrés hídrico controlado sobre la producción de aceites esenciales en hojas y flores del cv. Sanguinelli de Citrus sinensis y del cv. Clemenules de Citrus reticulata; estudio de los efectos fitotóxicos de los aceites esenciales en cuatro especies arvenses importantes en el área mediterránea, dos monocotiledóneas (Echinochloa crus-galli (L.) P.Beauv. y Avena fatua L.) y dos dicotiledóneas (Amaranthus retroflexus L. y Portulaca oleracea L.) mediante experimentos in vitro e in vivo; estudio del efecto bioestimulantes de las aguas residuales de la industria procesadora de cítricos sobre la comunidad microbiana del suelo; cuantificación de elementos de tierras raras en frutos de limón cultivados en diferentes áreas geográficas, para su posible uso como trazador geoquímico. Los principales resultados obtenidos son la caracterización de diferentes aceites esenciales, de los cuales los producidos por los residuos de la poda podrían ser utilizados como método de extracción de nuevos aceites esenciales con alto rendimiento. También se han encontrado sustancias nutracéuticas y farmacológicas en los hidrolatos industriales de naranja. Por otra parte, el aceite esencial industrial de limón mostró un buen potencial como agente herbicida, siendo, por tanto, de gran interés en la fabricación de herbicidas de origen natural, biodegradables y ecológicos. La aplicación del estrés hídrico controlado después del reposo invernal y, por tanto, en el momento de la brotación incrementó el diámetro final del fruto. La respuesta en el árbol no fue inmediata. La aplicación de hidrolatos de limón, naranja y mandarina al suelo junto al agua de riego, potenció los depósitos de C contribuyendo a aumentar la biomasa y mejoró la actividad microbiana. Estos resultados ponen de manifiesto el papel que los hidrolatos pueden desempeñar en la agricultura sostenible mejorando la fertilidad del suelo. Finalmente, el modelo de elementos de tierras raras podría utilizarse como una herramienta de conexión entre la producción de limón y el suelo del que proviene, contribuyendo, de esta manera, a su caracterización geográfica. En resumen, los resultados obtenidos en esta tesis contribuyen a impulsar el sector cítrico siciliano ya que: proporcionan medios para una agricultura sostenible; aumentan el valor de los subproductos y residuos de la industria; proponen aplicaciones para que el ciclo de producción y transformación sea más rentable y revalorizan los limones sicilianos vinculándolos a su zona de producción.[CA] En esta tesi doctoral es discutixen una sèrie de qüestions científiques relacionades amb la producció i el processament d'algunes espècies de cítrics d'especial rellevància a Sicília i a l'àrea mediterrània. Els objectius, acordats prèviament amb la indústria de cítrics "EuroFood" i finançats pel projecte d'investigació "PON Industrial Ph.D. - a.a. 2016/2017", es centren en estudiar la traçabilitat i sostenibilitat de la producció d'algunes espècies de cítrics, així com de trobar noves aplicacions als subproductes i productes de rebuig de la indústria, amb el fi de millorar la seua rentabilitat. Per tant, els temes que es desenvoluparan seran els següents: caracterització dels compostos bioactius presents en els olis essencials i en el l'hidrolato de diferents espècies de cítrics; seguiment de l'efecte de l'estrés hídric controlat en la producció d'olis essencials en fulles i flors del cv. Sanguinelli de Citrus sinensis i del cv. Clemenules de Citrus reticulata; estudi dels efectes fitotòxicos dels olis essencials de cítrics en quatre espècies arvenses importants en l'àrea mediterrània, dos monocotiledònies (Echinochloa crus-galli (L.) P.Beauv. i Avena fàtua L.) i dos dicotiledònies (Amaranthus retroflexus L. i Portulaca oleracea L.) per mitjà de diferents experiments in vitro i in vivo; estudi de l'efecte bioestimulant de les aigües residuals de la indústria processadora de cítrics sobre la comunitat microbiana del sòl; quantificació d'elements de terres rares en fruits de llima cultivats en diferents àrees geogràfiques, per al seu possible ús com a traçador geoquímic. Els principals resultats obtinguts són la caracterització de diferents olis essencials, dels quals els produïts pels residus de la poda podrien ser utilitzats com a mètode d'extracció de nous olis essencials amb alt rendiment. També s'han trobat substàncies nutracéutiques i farmacològiques en els hidrolats industrials de taronja. D'altra banda, l'oli essencial industrial de llima va mostrar un bon potencial com a agent herbicida, sent, per tant, de gran interés en la fabricació d'herbicides d'origen natural, biodegradables i ecològics. L'aplicació de l'estrés hídric controlat després del repòs hivernal i, per tant, en el moment de la brotació va incrementar el diàmetre final del fruit. La resposta en l'arbre no va ser immediata. L'aplicació de hidrolats de llima, taronja i mandarina al sòl amb l'aigua de reg, va augmentar els depòsits de carbó (C) contribuint a augmentar la biomassa i va millorar l'activitat microbiana. Aquests resultats posen de manifest el paper dels hidrolats en l'agricultura sostenible millorant, d'aquesta manera, la fertilitat del sòl. Finalment, el model d'elements de terres rares podria utilitzar-se com una ferramenta d'enllaç entre la producció de llima i el sòl del què prové, contribuint, d'esta manera, a la seua caracterització geogràfica. En resum, els resultats obtinguts en esta tesi doctoral contribueixen a impulsar el sector cítric sicilià ja que: - proporcionen mitjans per a una agricultura sostenible; - augmenten el valor dels subproductes i residus de la indústria; - proposen aplicacions perquè el cicle de producció i transformació siga de més rendabilitat; - revaloritzen les llimes d'origen sicilià vinculant-les a la seua zona de producció.[EN] In this doctoral thesis are discussed a series of scientific issues regarding citrus fruits production and processing, species of particular relevance in Sicily and in the Mediterranean area. Objectives and research activities addressed in this thesis were agreed with the citrus industry "EuroFood" and financed by the research project "PON industrial Ph.D. - a.a. 2016/2017". The research project was targeted to study the traceability and sustainability of citrus production, and to find new applications to the by-products and waste products of citrus industry with the objective of appreciate and enhance the Sicilian citrus industry. The following topics are addressed and developed in this thesis: - Characterization of the bioactive compounds present in essential oils (EOs) and in the hydrolate of different citrus species. - Monitoring of the effect of controlled water stress on the production of EOs in leaves and flowers of Citrus sinensis (L.) Osbeck cv. 'Sanguinelli' and Citrus reticulata Blanco cv. 'Clemenules'; -Test the phytotoxic effects of citrus EOs on four important weed species in the Mediterranean area, two monocotyledon (Echinochloa crus-galli (L.) P.Beauv. and Avena fatua L.) and two dicotyledon (Amaranthus retroflexus L., and Portulaca oleraceaL.) by different experiments in vitro and in greenhouse conditions; -Evaluation of the effect as natural biostimulants of wastewaters from citrus processing industry by its application on soil microbial community; -Quantification of rare earth elements in lemon fruits from different geographical areas for its possible use as geochemical tracers applied to lemon production. Different Citrus EOs have been characterized in this study and it has been verified that the oils produced by the pruning waste could be used for the extraction of EOs with high yields. In addition, nutraceutical and pharmacological substances have been found in the orange industrial hydrolates. Industrial lemon EO showed good potential when testing its herbicidal activity. Lemon EO represents a good basis for the development of herbicides of natural origin, biodegradable and eco-friendly. Thanks to the application of water stress after the winter vegetative restart, a conclusion found was that water stress increased the diameter of the fruit and it was observed that the effects of stress were not immediate on citrus trees, but were evident after some time. The study of the application of lemon, orange and mandarin hydrolates in the soil, as irrigation water provided the effects on stable and labile soil C pools, on biomass and microbial activity and on main microbial groups. Overall, hydrolates can play a role in sustainable agriculture because when added to a soil, they improve soil quality and fertility. The Rare Earth Element model could be used as a tool to connect lemon production to the soil where they were produced, for a possible geographical characterization and a direct link between the production and the territory or soil. The results obtained were very interesting because: - they provided the means for sustainable agriculture; - they increased the value of the by-products and waste products of the citrus industry; - they proposed applications for the citrus production and transformation cycle being more sustainable; - they could valorize the Sicilian lemons by linking them to their production area. These results could have practical repercussions in the production cycle of citrus fruits and give a boost to the Sicilian citrus fruit sector.Objectives and research activities addressed in this thesis were agreed with the citrus industry "EuroFood" and financed by the research project PON industrial Ph.D. - a.a. 2016/2017Ioppolo, A. (2020). Valorization of Citrus spp. Cultivars cultivated in Sicily for the industrial use of citrus derivatives and in particular for potential alternative uses of essential oils for the enhancement of the island's citrus production [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/159385TESI

Distribution of REEs in soil-citrus limon system(L.) Osbeck

The consumers have an increasing interest about food traceability with respect to safety, quality and typicality issues. The knowledge of a chemistry relationship between the soil and the agricultural products is an important tool for the quality assessment of food. Citrus Limon is the most important fruit tree crop in the world and the detection of potential fraud could improve by using tools linking the chemistry composition of this production to its typical growing area. This study use rare earth elements (REEs) as geochemical tracers. The REEs are a set of 14 elements, from lanthanum to lutetium that can be divided in light rare earth elements (LREEs), from La to Gd and heavy rare earth elements (HREEs), from Tb to Lu. The REEs have recognized as very useful tracers due to their generally coherent and predictable behaviour. The aim of the research is to observe whether the fruits of various cultivars of citrus cultivated on the same soil and their products (fruit and juice) reproduce the same distribution of REEs. Taking into account of our previous works carried out on grapevine – soil system [1,2], we applied the same technique to evaluate and trace the REEs distribution in soil– Citrus Limon fruits system. Sampling of soil and of fruits was carried out in the CREA experimental farm located in Acireale (CT, Sicily) where are present several Citrus Limon cultivars cultivated in Sicily. The REEs amount, the HREEs/LREEs relations and their distribution in the fruit and citrus juice with respect to the own soil were determined and calculated. The intriguing results obtained with a geochemical approach are the first on the soil–Citrus Limon fruits system

Effects of Citrus essential oils on weed emergence and on soil microorganisms

Weed invasion is a major problem for agricultural productivity since causes economic and environmental damages. Weed control can be achieved through chemical, mechanical, biological and cultural means. Although synthetic herbicides are effective for weed control, they have a negative impact on soil and the environment. Therefore, it is important to develop alternative means that are in the meanwhile effective and ecofriendly. EOs are commonly used for bactericidal, virucidal, fungicidal, antiparasitical, insecticidal, medicinal and cosmetic applications. Citrus EOs are the most widely used in the world for many purposes. Moreover, some studies have recently investigated their potential as herbicides. EOs can be extracted in different ways among which hydro distillation and cold pressing are commonly used. The two methods are based on different procedures. Hydro distillation is carried out with a Clevenger-apparatus that conducts the distillation process by boiling, condensing and decantation to separate the EOs. The cold pressing consist of crushing and pressing the peels thus leading to the formation of a watery emulsion. Then, the emulsion is centrifuged to separate out the EOs. Since no external substance are needed, this process ensures that the resulting EOs retains all their properties. The aim of this work was to evaluate the in vivo potential effects of Citrus EOs extracted by hydro distillation and cold pressing on weed emergence and on soil biochemical properties. The topsoil (5 cm) of an Inceptisol within the campus of University of Palermo was used for the experiment. 500 g of soil, air-dried and sieved at 1 cm, were used to fill each of the 24 aluminium pots (10 x 20 cm). then, soils were brought up to 100% of their water holding capacity (WHC) by adding firstly 150 mL of tap water (2/3 of WHC) followed by 70 mL of tap water (1/3 of WHC), by a anual sprayer, containing 8 mL L-1 of each one of the extracted EOs. Then, the soils were maintained at 50% of their water holding capacity during all the period of the experiment. Fitoil was used as emulsifier at a concentration of 1 ml L-1. Soils without EO, and with or without Fitoil, were considered as control. After one month the soils were moistened, plant biomass and height, and soil chemical and biochemical properties were evaluated. The experiment was carried out in quadruplicate to investigate the soil proprieties. In this work, the results are showed and discussed

Improvement of physical, chemical and biochemical proprieties of a salt affected Alfisol by addition of biochar and gypsum

Salinization is one of the major environmental problems threatening agricultural productivity. Soil salinization is defined as an excessive accumulation of salts within the soil profile. It negatively affects soil physical and chemical properties, as well as the biochemical ones. Reclamation of salt affected soils requires removal of soluble salts and Na+ from the soil exchange sites. Subsequently, salts are leached out the root zone by irrigation water when available. Gypsum (CaSO4·2H2O) is the most commonly used chemical amendment for reclamation of salt affected soils since it provides Ca2+ that replaces Na+ on the exchange sites and improves soil structure. Also organic amendments have been considered, but not extensively studied, for reclamation of salt affected soils. Recent studies have reported that biochar can be rich in nutrients like Ca2+ and Mg2+ and may enhance their availability in soil when added as amendment. Therefore, addition of biochar to a salt affected soil could aid in its remediation by supplying Ca2+ and Mg2+, and replacing Na+, improving aggregate stability and hydraulic conductivity. The objective of this study was to evaluate the effects of gypsum and biochar for the reclamation of a saline-sodic soil on some physical, chemical and biological properties. The topsoil of an Alfisol, about fifty meters far from the foreshore in the Petrosino coast (Sicily, Italy), was used for this experiment. The soil was air-dried and sieved at 2 mm. The main physical and chemical properties of the soil were: pH 7.3, clay 23 %, total carbonates 50.9 %, electrical conductivity 0.81 dS m-1 (1:5, w/v), total organic C 11.0 g kg-1, cation exchange capacity 24.8 cmol(+) kg-1, exchangeable sodium percentage 35 %. Two doses of gypsum (2.6 and 5.1 g kg-1 of soil) and two doses of biochar (4.2 and 8.3 g kg-1) were tested. The two doses of gypsum were calculated in order to decrease ESP from 35% to 25% and to 15%, respectively, whereas biochar was added in order to achieve an amount of 10 and 20 Mg ha-1. Following addition of gypsum and biochar, either alone or in combination, 100 g of soil were incubated at room temperature in 150 mL plastic pots and maintained at 50% of soil water holding capacity during all the duration of the experiment (22 days). One week after the incubation, three horse-radish seeds were sown. Then, after 13 days, plants were removed, oven dried at 60°C for 48 hours and weighed. The soils were analyzed to determine porosity, CEC, ESP, ECe, microbial biomass C, soil respiration and microbial community structure. The experiment was carried out in octuplicate. In this work, the results are reported and discusse

Soil bioindicators and weed emergence as affected by essential oils extracted from leaves of three different Eucalyptus species

The widespread use of synthetic herbicides has resulted in herbicide-resistant weeds, altered ecological balance and negative effects on human health. To overcome these problems, efforts are being made to reduce the reliance on synthetic herbicides and shift to natural products. Essential oils (EOs) extracted from plants have been demonstrated to have potential herbicide activity. EOs, composed by volatile organic compounds and characterized by a strong odor, are used in the cosmetic, pharmaceutical and food industries as they are thought to be safe compounds for humans, animals, and the environment. EOs extracted from Eucalyptus leaves have antimicrobial, antiviral, fungicidal, insecticidal, anti-inflammatory, anti-nociceptive and anti-oxidant effects. Moreover, in vitro studies have demonstrated that they have inhibitory effects on germination of seeds of many crops and weeds. The aim of this work was to evaluate the in vivo effects of EOs extracted from Eucalyptus leaves on both weed emergence and biochemical soil properties. Furthermore, since the diverse species of Eucalyptus have shown to have different biological activities, EOs were extracted from three Eucalyptus species (E. camaldulensis, E. globulus, E. occidentalis). Fresh leaves were collected from an afforested area near Piazza Armerina (province of Enna, Italy) and their EOs extracted by hydrodistillation. Soil samples were collected from the topsoil (<5 cm) of an Inceptisol within the experimental farm of the University of Palermo, air-dried and sieved at 1 cm. Five hundred grams of this soil were filled in each of 20 aluminum pots (10×20 cm). The soil samples were brought up to 100% of the water holding capacity (WHC) by adding 150 mL of tap water, followed by 70 mL of tap water containing 8 mL L-1 of one of the three extracted EOs. This experimental test was repeated for remaining two EOs. Fitoil was used as emulsifier at a concentration of 0.1% (v/v). The control consisted of the soil treated as the EO treatment but with Fitoil only. The soils were incubated in greenhouse conditions. After 2 days, the 100% WHC halved and then it was kept to this level (50% WHC) by watering soil daily. The experiment was carried out in quadruplicate. After one month the soil were brought up to 100% of WHC, plant biomass and height of germinated weeds and soil biochemical properties were evaluated. This work reports the results and discuss them

Phytotoxic potential of Citrus essential oils on weed species

Environmental constraints of crop production systems have stimulated interest in alternative weed management strategies. In fact, the continued use of synthetic herbicides may threaten sustainable agricultural production and result in serious ecological and environmental problems, such as the increased incidence of resistance in weeds to important herbicides and increased environmental pollution and health hazards. Public awareness and demand for environmentally safer herbicides with less persistence and less contaminating potential make searches for new weed control strategies. Citrus Essential oils are generally used in the cosmetic, medicinal, and food industries, and are thought to be safe compounds for humans, animals, and the environment. EOs can be extracted by hydro distillation and cold pressing. The two methods are based on different procedures. Hydro distillation is carried out with a Clevenger-apparatus that conducts the distillation process by boiling, condensing and decantation to separate the EOs. The cold pressing consist of crushing and pressing the peels thus leading to the formation of a watery emulsion. Then, the emulsion is centrifuged to separate out the EOs. Since no external substance are needed, this process ensures that the resulting EOs retains all their properties. The allelopathic and phytotoxic effects of EOs obtained from other species and their potential use for weed management has been well documented. The objectives of this study were to evaluate in vitro the phytotoxic effects of Citrus EOs (Citrus sinensis, Citrus limon and Citrus reticulata) extracted by hydro distillation and cold pressing on main weed species (Amaranthus retroflexus, Portulaca oleracea., Echinochloa crus-galli, Avena sativa). For all EOs six concentrations were tested (0.5, 1, 2, 4, 8, 12) μl/ml and 5 repetitions with 20 seeds each (for dicotyledons) or 10 repetitions with 10 seeds each (for monocotyledons) were performed. They were applied for one hundred seeds for concentration. Twenty seeds were placed into 9 cm diameter Petri dishes for Amarantus and Portulaca. In each Petri dish, 5 ml of distilled water were added. This volume kept the filter papers uniformly soaked-wet without flooding. For Avena and Echinocloa ten seeds were placed into petri dishes and 6 ml of distilled water was added. The essential oil was placed in a sheet of filter papers in contact with the seeds. The controls were prepared with the same quantities of distilled water. Petri dishes were incubated in the room germination (EQUITEC) at 20/30 °C (±1 °C), alternating temperature (6/18 h dark and light (cool white Radium NL 36W/840; 3100 lm)). Dishes were sealed to reduce evaporation, and no more additional water was supplied during the tests. To evaluate the possible phytotoxic effects of the essential oils and their main compounds on seed germination and seedling growth data were registered by taking photos after 3,5, 7, 10 and 14 days after incubation and will be processed using Digimizer. Then data will be analysed and discussed

PHYTOTOXIC POTENTIAL OF EUCALYPTUS ESSENTIAL OILS FOR WEED CONTROL

The widespread use of synthetic herbicides has resulted in herbicide-resistant weeds, disturbed ecological balance and negative effects on human health. Due to this fact, it is necessary to rely on alternative weed control strategies using natural compounds released by plants, such as essential oils (EOs). EOs have a short half-life since they are biodegradable, and are safer than synthetic compounds, with little damage to the environment, without even contaminating ground water (Topal and Kocaçalıskan 2006). Essential oils from different species contain allelochemical compounds that possess significant phytotoxic activity. Azizi and Fuji (2006) demonstrated that Eucalyptus (family Myrtaceae) EOs showed strong inhibitory effects on germination of seeds of many crops and weeds. The aim of this work is to evaluate the phytotoxic potential effect of four Eucalyptus species (E. camaldulensis, E. lesouefi, E.occidentalis, E. torquata) EOs, on weed seed germination of two dicotyledons (Amaranthus retroflexus and Portulaca oleracea) and two monocotyledons (Avena fatua and Echinochloa crus-galli) which are considered among the most serious weeds for the Mediterranean crops. Fresh leaves of E. camaldulensis and E. occidentalis were collected in afforested area near Agrigento (Sicily, Italy) during November and December of 2017. The leaves of E. lesouefi and E. torquata were collected during March, April and May from Gabes, located in the South of Tunisia on 2015. The EOs were extracted from each species by steam distillation with a Clevenger apparatus according to the standard procedure described in the European Pharmacopoeia (1975), and stored at 4 °C until they were used. Weed seeds of A. retroflexus, P. oleracea, A. fatua and E. crus-galli were purchased from Herbiseed (England). To test the phytotoxicity activity of the EOs, different concentrations were prepared: 0.125; 0.25; 0.5; 1; 2; 4 µl/ml for dicotyledons and 0.5; 1; 2; 4; 8; 12 µl/ml for monocotyledons. The oils were loaded on the inner side of two layer of filter paper (73 g/m2) in Petri dishes (9 cm diameter), after sowing twenty seeds of each weed type (10 in case of monocotyledons) on the base of the Petri dishes, in two other layers of filter paper wetted with 5 ml of distilled water, in case of the dicotyledons, and 6 ml for the monocotyledons. The controls were prepared with the same quantities of distilled water. For each concentration, five replications were maintained (10 in case of monocotyledons). All the Petri dishes were kept in a growth chamber maintained alternating 30.0 +/- 0.1 °C, 16 h in light and 20.0 +/- 0.1 °C, 8 h in dark. To register germination and seedling length data, photos were taken after 3, 5, 7, 10 and 14 days, and they will be processed with Digimizer. In the poster, the results will be illustrated and discussed

Valorization of Citrus spp. Cultivars cultivated in Sicily for the industrial use of citrus derivatives and in particular for potential alternative uses of essential oils for the enhancement of the island's citrus production

In this doctoral thesis are discussed a series of scientific issues regarding citrus fruits production and processing, species of particular relevance in Sicily and in the Mediterranean area. Objectives and research activities addressed in this thesis were agreed with the citrus industry "EuroFood" and financed by the research project "PON industrial Ph.D. - a.a. 2016/2017". The research project was targeted to study the traceability and sustainability of citrus production, and to find new applications to the by-products and waste products of citrus industry with the objective of appreciate and enhance the Sicilian citrus industry. The following topics are addressed and developed in this thesis: - Characterization of the bioactive compounds present in essential oils (EOs) and in the hydrolate of different citrus species. - Monitoring of the effect of controlled water stress on the production of EOs in leaves and flowers of Citrus sinensis (L.) Osbeck cv. ‘Sanguinelli’ and Citrus × clementina cv. ‘Clemenules’; -Test the phytotoxic effects of citrus EOs on four important weed species in the Mediterranean area, two monocotyledon (Echinochloa crus-galli (L.) P.Beauv. and Avena fatua L.) and two dicotyledon (Amaranthus retroflexus L., and Portulaca oleracea L.) by different experiments in vitro and in greenhouse conditions; -Evaluation of the effect as natural biostimulants of wastewaters from citrus processing industry by its application on soil microbial community; -Quantification of rare earth elements in lemon fruits from different geographical areas for its possible use as geochemical tracers applied to lemon production. Different Citrus EOs have been characterized in this study and it has been verified that the oils produced by the pruning waste could be used for the extraction of EOs with high yields. In addition, nutraceutical and pharmacological substances have been found in the orange industrial hydrolates. II Industrial lemon EO showed good potential when testing its herbicidal activity. Lemon EO represents a good basis for the development of herbicides of natural origin, biodegradable and eco-friendly. Thanks to the application of water stress after the winter vegetative restart, a conclusion found was that water stress increased the diameter of the fruit and it was observed that the effects of stress were not immediate on citrus trees, but were evident after some time. The study of the application of lemon, orange and mandarin hydrolates in the soil, as irrigation water provided the effects on stable and labile soil C pools, on biomass and microbial activity and on main microbial groups. Overall, hydrolates can play a role in sustainable agriculture because when added to a soil, they improve soil quality and fertility. The Rare Earth Element model could be used as a tool to connect lemon production to the soil where they were produced, for a possible geographical characterization and a direct link between the production and the territory or soil. The results obtained were very interesting because: - they provided the means for sustainable agriculture; - they increased the value of the by-products and waste products of the citrus industry; - they proposed applications for the citrus production and transformation cycle being more sustainable; - they could valorize the Sicilian lemons by linking them to their production area. These results could have practical repercussions in the production cycle of citrus fruits and give a boost to the Sicilian citrus fruit sector

Standard polynomials and matrices with superinvolutions

Let Mn(F) be the algebra of n x n matrices over a field F of characteristic zero. The superinvolutions ∗ on Mn(F) were classified by Racine in [12]. They are of two types, the transpose and the orthosymplectic superinvolution. This paper is devoted to the study of ∗-polynomial identities satisfied by Mn(F). The goal is twofold. On one hand, we determine the minimal degree of a standard polynomial vanishing on suitable subsets of symmetric or skew-symmetric matrices for both types of superinvolutions. On the other, in case of M2(F), we find generators of the ideal of ∗-identities and we compute the corresponding sequences of cocharacters and codimensions

Varieties of Algebras with Superinvolution of Almost Polynomial Growth

Let A be an associative algebra with superinvolution ∗ over a field of characteristic zero and let c_n∗(A) be its sequence of corresponding ∗-codimensions. In case A is finite dimensional, we prove that such sequence is polynomially bounded if and only if the variety generated by A does not contain three explicitly described algebras with superinvolution. As a consequence we find out that no intermediate growth of the ∗-codimensions between polynomial and exponential is allowed