Serenella Nardi | Università degli Studi di Padova (original) (raw)

Papers by Serenella Nardi

Chemical and Biological Technologies in Agriculture, Aug 11, 2023

Background The threatening impact of conventional agriculture (CA) on soils could be due to the d... more Background The threatening impact of conventional agriculture (CA) on soils could be due to the detrimental effects on soil microbial communities. Conversely, organic agriculture (OA) is envisaged as potentially enhancing helpful microbial communities and is proposed as environmentally sustainable. The soil microbiome influences soil health and quality, hence, it requires deeper investigation and understanding. In this study, applying 16S metabarcoding and qPCR techniques, we compared the microbial patterns of long-term organically and conventionally managed soils to explore their similarities and differences. Results Total DNA quantification showed an over 20-fold higher amount of DNA in OA soils (mean = 22.1 ± 3.92 μg g −1), compared to CA soils (mean = 0.95 ± 0.17 μg g −1). While 16S metabarcoding evidenced the absence of significant differences among communities of the two farming systems in terms of ecological indices, the qPCR analyses targeting functional genes reported a significantly higher abundance of all considered targets in OA sites spanning up to four-fold log increases. While OA and CA did not appear to affect overall bacterial diversity or evenness per se, qPCR-based functional analysis in OA showed a consistently higher abundance of all the salient microbial genes tested, when compared to CA, underlying a potentially beneficial impact on soil fertility and sustainability. Conclusions In essence, the sequencing-based analysis of absolute bacterial diversity could not differentiate the farming systems based on the amount of diversity but identified a unique set of taxa defining each. Hence, pairing this evaluation with the qPCR-based functional gene analyses can be a suitable approach to distinguish the exerted effects of CA or OA on soils.

Journal of Applied Phycology, Oct 14, 2017

The characterization of nutrient and biostimulant effects in crops is complex and needs rigorous ... more The characterization of nutrient and biostimulant effects in crops is complex and needs rigorous evaluations. In this study, we evaluated morphological and molecular responses induced by microalgae (Chlorella vulgaris and Scenedesmus quadricauda) extracts in Beta vulgaris L. The two microalgae extracts were firstly characterized by CNS, Fourier transform infrared spectroscopic analysis (FT-IR), and carbon-13 nuclear magnetic resonance (13 C NMR). Seedlings were grown in Hoagland's solution under controlled conditions. After 5 days of growth, 2 mL L −1 (1 mg C org L −1) and 4 mL L −1 (2 mg C org L −1) of the two microalgae extracts were added to the Hoagland solution. Roots were sampled 36 h after treatments. Inductively coupled plasma spectrometry (ICP-OES) and nanofluidic real-time PCR (OpenArray system) were used for sample profiling. Fifty-three sugar beet genes putatively involved in sulfate starvation were tested in treated and untreated samples. Root morphological traits were measured by means of a scanner-based image analysis system. Multivariate statistical analysis revealed no significant changes in the ionomic profile of Hoagland's solutions treated with the two microalgae extracts with respect to that of the untreated solution. At the molecular level, microalgae extract supplies upregulated many of the evaluated genes. Functional categorization revealed these genes to be related to various biological pathways and processes including primary and secondary metabolism and intracellular transport. At the morphological level, the treated seedlings showed significantly higher values for root traits related to soil exploration and nutrient uptake, such as total root length, fine root length (diameter < 0.5 mm), and number of root tips, than the untreated plants. These data indicate that microalgae extracts have biostimulant effects on the expression of root traits and genes related to nutrient acquisition in sugar beet.

Since 2000 a multidisciplinary team of archaeologists, geologists and paleobotanists has been car... more Since 2000 a multidisciplinary team of archaeologists, geologists and paleobotanists has been carrying out joint investigations at Ca’ Tron, a 11 km2 estate located at the northern lagoon of Venice and included in the east countryside of the ancient Venetian-Roman Altinum. During the systematic survey conducted in Ca’ Tron estate nine Roman sites were identified, three of which were excavated in extension. Two rural settlements are analyzed in this paper, both attended since Ist to IV-V th century AD, having different planimetric features and economic role: the first one was a farm with several outbuildings, the second one was specialized in breeding sheep, with a large rectangular building, interpretable as a sheepfold on the basis of comparison with the Roman “bergeries” investigated in the Crau of Arles (Provence). Particularly relevant to the understanding of economic activities were the micromorphological analysis of soil types, chemical and biological, especially to clarify th...

Journal of Microbiology and Biotechnology, 2013

The fermented manure derivative known as Preparation 500 is traditionally used as a field spray i... more The fermented manure derivative known as Preparation 500 is traditionally used as a field spray in biodynamic agriculture for maintaining and increasing soil fertility. This work aimed at characterizing the product from a microbiological standpoint and at assaying its bioactive properties. The approach involved molecular taxonomical characterization of the culturable microbial community; ARISA fingerprints of the total bacteria and fungal communities; chemical elemental macronutrient analysis via a combustion analyzer; activity assays for six key enzymes; bioassays for bacterial quorum sensing and chitolipooligosaccharide production; and plant hormonelike activity. The material was found to harbor a bacterial community of 2.38 × 10 8 CFU/g dw dominated by Grampositives with minor instances of Actinobacteria and Gammaproteobacteria. ARISA showed a coherence of bacterial assemblages in different preparation lots of the same year in spite of geographic origin. Enzymatic activities showed elevated values of β-glucosidase, alkaline phosphatase, chitinase, and esterase. The preparation had no quorum sensing-detectable signal, and no rhizobial nod gene-inducing properties, but displayed a strong auxin-like effect on plants. Enzymatic analyses indicated a bioactive potential in the fertility and nutrient cycling contexts. The IAA activity and microbial degradation products qualify for a possible activity as soil biostimulants. Quantitative details and possible modes of action are discussed.

An energy dispersive X-ray fluorescence method for trace element analysis in plants (leaves and r... more An energy dispersive X-ray fluorescence method for trace element analysis in plants (leaves and roots) is presented. The method is characterized by the use of a secondary target excitation, thin specimen, and microwave acid digestion. The accuracy is about 10% and the sensitivity is in the range 10-50 ng/cm2. The analysis time (from dry sample to concentration data) is about 4 x 10(3) s. The effects of Cr in sewage sludge on barley seedling growth is presented.

Journal of Soils and Sediments, Aug 1, 2016

Purpose Processes that lead to soil organic carbon (SOC) protection depend on both soil porosity ... more Purpose Processes that lead to soil organic carbon (SOC) protection depend on both soil porosity and structure organization, as well as chemical and biological properties. In particular, the soil micro-nano porosity (<30 μm) regulates microorganism accessibility to the soil pore system and offers surfaces for organic carbon adsorption and intercalation into soil minerals. The aim of this work was to investigate how pore size distribution can selectively protect specific carbon pools in different aggregate size fractions, by considering the effects of long-term application of farmyard manure (FYM) and mineral (Min) fertilization. Materials and methods Macroaggregates (250-2000 μm), microaggregates (53-250 μm), and silt-clay (<53 μm) fractions of three different soils (clayey, peaty, and sandy) were separated by wet sieving technique and then subjected to chemical and physical analysis. Sample porosity and pore size distribution were analyzed using mercury intrusion porosimetry (MIP), while SOC chemical structure was characterized by means of nuclear magnetic resonance (13 C crosspolarization-magic angle spinning nuclear magnetic resonance (CP MAS 13 C NMR)) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopies. Results and discussion Results showed that FYM increased organic (OC) and humic carbon (HC) content compared to the Min fertilization and unfertilized soils. However, it caused a gradual decrease in O,N-alkyl C, and alkyl C of humic C from macroaggregate to silt-clay fractions, suggesting an advanced state of humic component degradation as revealed by CP MAS 13 C NMR, DRIFT analyses. MIP analysis showed a clear increase of micropores (5-30 μm) and cryptopores (0.0035-0.1 μm) from macroaggregate to silt-clay fractions, while minor differences were observed among the treatments. The application of principal component analysis to mineral soil fractions identified the formation of three main clusters, where (i) macroaggregates of clayey soil were mainly associated to cryptopores and OC and (ii) microaggregates and siltclay fraction were mainly isolated by carbonyl C, ultramicropores, and total porosity. The third cluster was associated with medium and fine sand of the sand soil fraction as coupled with O,N-alkyl C, anomeric C, mesopores, and HC/ OC ratio. Conclusions Overall, this study indicates that pore size distribution may be a valuable indicator of soil capacity to sequester carbon, due to its direct influence on SOC linkages with soil aggregates and the positive effects against SOC decomposition phenomena. In this context, micropore-to nanoporedominated structures (e.g., clayey soil) were able to protect OC compounds by interacting with mineral surfaces and intercalation with phyllosilicates, while meso/macroporedominated structures (i.e., sandy soil) exhibited their low ability to protect the organic components.

Agronomy, Aug 12, 2019

The main aim of this study is to identify and investigate specific humates (Hs) as potential bios... more The main aim of this study is to identify and investigate specific humates (Hs) as potential biostimulants. Five specialty lignosulfonates (LS1-5), one commercial leonardite-humate (PH), and one commercial lignosulfonate (LH), were analyzed for their carbon, nitrogen, and sulfur contents, and the distribution of functional groups using Fourier transform infrared (FTIR) and Raman spectroscopies. Hs were further supplied for two days to Zea mays L. in hydroponics to test their capacity to trigger changes in physiological target-responses. LS1, LS2, LS3, and LS5 determined the most pronounced effects on plant growth and accumulation of proteins and phenolics, perhaps because of their chemical and spectroscopic features. Root growth was more increased (+51-140%) than leaf growth (+5-35%). This effect was ascribed to higher stimulation of N metabolism in roots according to the increased activity of N-assimilation enzymes (GS and GOGAT) and high consumption of sugars for energy-dependent processes. Increased values of RuBisCO, SPAD (Soil Plant Analysis Development values), and leaf sugar accumulation refer to enhanced photosynthesis attributed to Hs. We conclude that Hs tested in this study functioned as biostimulants, but the specialty lignosulfonates were more efficient in this role, possibly because of the type of starting material and process used for their production, which may have influenced their chemical properties.

Agriculture, Ecosystems & Environment, Oct 1, 2016

Continued fertilizations have led to soil phosphorus (P) concentrations that exceed those require... more Continued fertilizations have led to soil phosphorus (P) concentrations that exceed those required for optimal plant growth. In this study, P accumulation and leaching were investigated in 1-m profile of three reconstructed soils (sandy, SDY; clay, CLY; peaty, PTY) typical of the Po Valley (northern Italy) following long-term (44 years) farmyard manure and mineral applications and untreated. Soil test P was determined by extracting with ammonium oxalate (P Ox), Mehlich-3 (P M3) and Olsen (P Ols) solutions, whereas soil P release was estimated by water extraction (P H2O). Two single-point sorption indices (PSI 19.4 and PSI 50) were used to assess the P sorption capacity in these soils. The relationship between extractable P forms and water P was also modelled as a segmented line. Soil test P resulted as being affected by type of soil, treatment and depth. Farmyard manure increased the P forms by 7.7-fold that of untreated down to 50 cm in CLY and PTY, and 28-fold untreated down to 90 cm in SDY, thus indicating both accumulation and leaching of P. The P sorption indices were affected by type of soil, treatment and depth. P accumulation was also confirmed by increments of PSI 50 in the manure-treated deeper layers, likely due to increased organic matter and/or precipitation and coprecipitation of P with carbonates in these soils. Although mineral fertilization also increased extractable P it was with lower magnitude than manure on P leaching and P sorption indices. From the segmented lines between P H2O and extractable P, the presence of change points in CLY and PTY revealed P H2O concentrations above the environmental threshold values. In the light-textured SDY soils, the low P sorption capacity and absence of change points evidenced high P leaching and potential contamination of surface and ground waters, in particular when manure was used. 2016 Elsevier B.V. All rights reserved.

Journal of Archaeological Science: Reports

VIII Convegno Nazionale della INTERNATIONAL HUMIC SUBSTANCES SOCIETY, 2009

Chemical and Biological Technologies in Agriculture, Aug 11, 2023

Background The threatening impact of conventional agriculture (CA) on soils could be due to the d... more Background The threatening impact of conventional agriculture (CA) on soils could be due to the detrimental effects on soil microbial communities. Conversely, organic agriculture (OA) is envisaged as potentially enhancing helpful microbial communities and is proposed as environmentally sustainable. The soil microbiome influences soil health and quality, hence, it requires deeper investigation and understanding. In this study, applying 16S metabarcoding and qPCR techniques, we compared the microbial patterns of long-term organically and conventionally managed soils to explore their similarities and differences. Results Total DNA quantification showed an over 20-fold higher amount of DNA in OA soils (mean = 22.1 ± 3.92 μg g −1), compared to CA soils (mean = 0.95 ± 0.17 μg g −1). While 16S metabarcoding evidenced the absence of significant differences among communities of the two farming systems in terms of ecological indices, the qPCR analyses targeting functional genes reported a significantly higher abundance of all considered targets in OA sites spanning up to four-fold log increases. While OA and CA did not appear to affect overall bacterial diversity or evenness per se, qPCR-based functional analysis in OA showed a consistently higher abundance of all the salient microbial genes tested, when compared to CA, underlying a potentially beneficial impact on soil fertility and sustainability. Conclusions In essence, the sequencing-based analysis of absolute bacterial diversity could not differentiate the farming systems based on the amount of diversity but identified a unique set of taxa defining each. Hence, pairing this evaluation with the qPCR-based functional gene analyses can be a suitable approach to distinguish the exerted effects of CA or OA on soils.

Journal of Applied Phycology, Oct 14, 2017

The characterization of nutrient and biostimulant effects in crops is complex and needs rigorous ... more The characterization of nutrient and biostimulant effects in crops is complex and needs rigorous evaluations. In this study, we evaluated morphological and molecular responses induced by microalgae (Chlorella vulgaris and Scenedesmus quadricauda) extracts in Beta vulgaris L. The two microalgae extracts were firstly characterized by CNS, Fourier transform infrared spectroscopic analysis (FT-IR), and carbon-13 nuclear magnetic resonance (13 C NMR). Seedlings were grown in Hoagland's solution under controlled conditions. After 5 days of growth, 2 mL L −1 (1 mg C org L −1) and 4 mL L −1 (2 mg C org L −1) of the two microalgae extracts were added to the Hoagland solution. Roots were sampled 36 h after treatments. Inductively coupled plasma spectrometry (ICP-OES) and nanofluidic real-time PCR (OpenArray system) were used for sample profiling. Fifty-three sugar beet genes putatively involved in sulfate starvation were tested in treated and untreated samples. Root morphological traits were measured by means of a scanner-based image analysis system. Multivariate statistical analysis revealed no significant changes in the ionomic profile of Hoagland's solutions treated with the two microalgae extracts with respect to that of the untreated solution. At the molecular level, microalgae extract supplies upregulated many of the evaluated genes. Functional categorization revealed these genes to be related to various biological pathways and processes including primary and secondary metabolism and intracellular transport. At the morphological level, the treated seedlings showed significantly higher values for root traits related to soil exploration and nutrient uptake, such as total root length, fine root length (diameter < 0.5 mm), and number of root tips, than the untreated plants. These data indicate that microalgae extracts have biostimulant effects on the expression of root traits and genes related to nutrient acquisition in sugar beet.

Since 2000 a multidisciplinary team of archaeologists, geologists and paleobotanists has been car... more Since 2000 a multidisciplinary team of archaeologists, geologists and paleobotanists has been carrying out joint investigations at Ca’ Tron, a 11 km2 estate located at the northern lagoon of Venice and included in the east countryside of the ancient Venetian-Roman Altinum. During the systematic survey conducted in Ca’ Tron estate nine Roman sites were identified, three of which were excavated in extension. Two rural settlements are analyzed in this paper, both attended since Ist to IV-V th century AD, having different planimetric features and economic role: the first one was a farm with several outbuildings, the second one was specialized in breeding sheep, with a large rectangular building, interpretable as a sheepfold on the basis of comparison with the Roman “bergeries” investigated in the Crau of Arles (Provence). Particularly relevant to the understanding of economic activities were the micromorphological analysis of soil types, chemical and biological, especially to clarify th...

Journal of Microbiology and Biotechnology, 2013

The fermented manure derivative known as Preparation 500 is traditionally used as a field spray i... more The fermented manure derivative known as Preparation 500 is traditionally used as a field spray in biodynamic agriculture for maintaining and increasing soil fertility. This work aimed at characterizing the product from a microbiological standpoint and at assaying its bioactive properties. The approach involved molecular taxonomical characterization of the culturable microbial community; ARISA fingerprints of the total bacteria and fungal communities; chemical elemental macronutrient analysis via a combustion analyzer; activity assays for six key enzymes; bioassays for bacterial quorum sensing and chitolipooligosaccharide production; and plant hormonelike activity. The material was found to harbor a bacterial community of 2.38 × 10 8 CFU/g dw dominated by Grampositives with minor instances of Actinobacteria and Gammaproteobacteria. ARISA showed a coherence of bacterial assemblages in different preparation lots of the same year in spite of geographic origin. Enzymatic activities showed elevated values of β-glucosidase, alkaline phosphatase, chitinase, and esterase. The preparation had no quorum sensing-detectable signal, and no rhizobial nod gene-inducing properties, but displayed a strong auxin-like effect on plants. Enzymatic analyses indicated a bioactive potential in the fertility and nutrient cycling contexts. The IAA activity and microbial degradation products qualify for a possible activity as soil biostimulants. Quantitative details and possible modes of action are discussed.

An energy dispersive X-ray fluorescence method for trace element analysis in plants (leaves and r... more An energy dispersive X-ray fluorescence method for trace element analysis in plants (leaves and roots) is presented. The method is characterized by the use of a secondary target excitation, thin specimen, and microwave acid digestion. The accuracy is about 10% and the sensitivity is in the range 10-50 ng/cm2. The analysis time (from dry sample to concentration data) is about 4 x 10(3) s. The effects of Cr in sewage sludge on barley seedling growth is presented.

Journal of Soils and Sediments, Aug 1, 2016

Purpose Processes that lead to soil organic carbon (SOC) protection depend on both soil porosity ... more Purpose Processes that lead to soil organic carbon (SOC) protection depend on both soil porosity and structure organization, as well as chemical and biological properties. In particular, the soil micro-nano porosity (<30 μm) regulates microorganism accessibility to the soil pore system and offers surfaces for organic carbon adsorption and intercalation into soil minerals. The aim of this work was to investigate how pore size distribution can selectively protect specific carbon pools in different aggregate size fractions, by considering the effects of long-term application of farmyard manure (FYM) and mineral (Min) fertilization. Materials and methods Macroaggregates (250-2000 μm), microaggregates (53-250 μm), and silt-clay (<53 μm) fractions of three different soils (clayey, peaty, and sandy) were separated by wet sieving technique and then subjected to chemical and physical analysis. Sample porosity and pore size distribution were analyzed using mercury intrusion porosimetry (MIP), while SOC chemical structure was characterized by means of nuclear magnetic resonance (13 C crosspolarization-magic angle spinning nuclear magnetic resonance (CP MAS 13 C NMR)) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopies. Results and discussion Results showed that FYM increased organic (OC) and humic carbon (HC) content compared to the Min fertilization and unfertilized soils. However, it caused a gradual decrease in O,N-alkyl C, and alkyl C of humic C from macroaggregate to silt-clay fractions, suggesting an advanced state of humic component degradation as revealed by CP MAS 13 C NMR, DRIFT analyses. MIP analysis showed a clear increase of micropores (5-30 μm) and cryptopores (0.0035-0.1 μm) from macroaggregate to silt-clay fractions, while minor differences were observed among the treatments. The application of principal component analysis to mineral soil fractions identified the formation of three main clusters, where (i) macroaggregates of clayey soil were mainly associated to cryptopores and OC and (ii) microaggregates and siltclay fraction were mainly isolated by carbonyl C, ultramicropores, and total porosity. The third cluster was associated with medium and fine sand of the sand soil fraction as coupled with O,N-alkyl C, anomeric C, mesopores, and HC/ OC ratio. Conclusions Overall, this study indicates that pore size distribution may be a valuable indicator of soil capacity to sequester carbon, due to its direct influence on SOC linkages with soil aggregates and the positive effects against SOC decomposition phenomena. In this context, micropore-to nanoporedominated structures (e.g., clayey soil) were able to protect OC compounds by interacting with mineral surfaces and intercalation with phyllosilicates, while meso/macroporedominated structures (i.e., sandy soil) exhibited their low ability to protect the organic components.

Agronomy, Aug 12, 2019

The main aim of this study is to identify and investigate specific humates (Hs) as potential bios... more The main aim of this study is to identify and investigate specific humates (Hs) as potential biostimulants. Five specialty lignosulfonates (LS1-5), one commercial leonardite-humate (PH), and one commercial lignosulfonate (LH), were analyzed for their carbon, nitrogen, and sulfur contents, and the distribution of functional groups using Fourier transform infrared (FTIR) and Raman spectroscopies. Hs were further supplied for two days to Zea mays L. in hydroponics to test their capacity to trigger changes in physiological target-responses. LS1, LS2, LS3, and LS5 determined the most pronounced effects on plant growth and accumulation of proteins and phenolics, perhaps because of their chemical and spectroscopic features. Root growth was more increased (+51-140%) than leaf growth (+5-35%). This effect was ascribed to higher stimulation of N metabolism in roots according to the increased activity of N-assimilation enzymes (GS and GOGAT) and high consumption of sugars for energy-dependent processes. Increased values of RuBisCO, SPAD (Soil Plant Analysis Development values), and leaf sugar accumulation refer to enhanced photosynthesis attributed to Hs. We conclude that Hs tested in this study functioned as biostimulants, but the specialty lignosulfonates were more efficient in this role, possibly because of the type of starting material and process used for their production, which may have influenced their chemical properties.

Agriculture, Ecosystems & Environment, Oct 1, 2016

Continued fertilizations have led to soil phosphorus (P) concentrations that exceed those require... more Continued fertilizations have led to soil phosphorus (P) concentrations that exceed those required for optimal plant growth. In this study, P accumulation and leaching were investigated in 1-m profile of three reconstructed soils (sandy, SDY; clay, CLY; peaty, PTY) typical of the Po Valley (northern Italy) following long-term (44 years) farmyard manure and mineral applications and untreated. Soil test P was determined by extracting with ammonium oxalate (P Ox), Mehlich-3 (P M3) and Olsen (P Ols) solutions, whereas soil P release was estimated by water extraction (P H2O). Two single-point sorption indices (PSI 19.4 and PSI 50) were used to assess the P sorption capacity in these soils. The relationship between extractable P forms and water P was also modelled as a segmented line. Soil test P resulted as being affected by type of soil, treatment and depth. Farmyard manure increased the P forms by 7.7-fold that of untreated down to 50 cm in CLY and PTY, and 28-fold untreated down to 90 cm in SDY, thus indicating both accumulation and leaching of P. The P sorption indices were affected by type of soil, treatment and depth. P accumulation was also confirmed by increments of PSI 50 in the manure-treated deeper layers, likely due to increased organic matter and/or precipitation and coprecipitation of P with carbonates in these soils. Although mineral fertilization also increased extractable P it was with lower magnitude than manure on P leaching and P sorption indices. From the segmented lines between P H2O and extractable P, the presence of change points in CLY and PTY revealed P H2O concentrations above the environmental threshold values. In the light-textured SDY soils, the low P sorption capacity and absence of change points evidenced high P leaching and potential contamination of surface and ground waters, in particular when manure was used. 2016 Elsevier B.V. All rights reserved.

Journal of Archaeological Science: Reports

VIII Convegno Nazionale della INTERNATIONAL HUMIC SUBSTANCES SOCIETY, 2009

Quaternary International 243, PP. 280-292, 2011

Fondo Paviani is a Bronze Age archaeological site located in the Valli Grandi Veronesi area in th... more Fondo Paviani is a Bronze Age archaeological site located in the Valli Grandi Veronesi area in the lower Venetian plain (northeastern Italy). The inhabited area is surrounded by a moat and a quadrangular rampart, a structural characteristic specific to the so-called terramare, villages that were common in the alluvial plains both north and south of the Po River during the middle and recent Bronze Age. Dark-coloured anthropogenic deposits occurring inside the site of Fondo Paviani were exposed during archaeological excavations and along stratigraphic cross-sections. Here, the micropedological and pedochemical characters of the deposits have been used as a key to decipher the formation processes and post-depositional modifications involved in order to reconstruct the human activities and environmental conditions recorded in the stratigraphy. This reconstruction has been formulated by integrating the abovementioned analytical techniques with geomorphological, pedological and archaeological data.