Massimo Fagnano

Crops' Responses to Ozone in Mediterranean Environments

The Mediterranean environment, and most of the Italian peninsula, presents some peculiarities in terms of crop response to O(3) since most physiological mechanisms activated upon O(3) exposure, such as stomatal closure, often overlap and interact with those that underlie plant adaptation to drought and hyperosmotic stress, which are typical of these environments. OTC and EDU experiments have demonstrated that O(3) causes strong yield losses when crops are grown without water limitations. However, exposure to water or saline stress significantly reduced O(3) effects on crop yield. In this review, we present the methodological approaches that have been used to study plant-ozone interactions in Italy as well as biochemical, physiological and agronomic responses for representative cropping systems of the Mediterranean climate.

Prebiotic content of bread prepared with flour from immature wheat grain and selected dextran-producing lactic acid bacteria.

ABSTRACT In the last few years the need to produce food with added value has fueled the search for new ingredients and health-promoting compounds. In particular, to improve the quality of bakery products with distinct nutritional properties, the identification of new raw materials, appropriate technologies, and specific microbial strains is necessary. In this study, different doughs were prepared, with 10% and 20% flour from immature wheat grain blended with type “0 America” wheat flour. Immature flour was obtained from durum wheat grains harvested 1 to 2 weeks after anthesis. Doughs were obtained by both the straight-dough and sourdough processes. Two selected exopolysaccharide-producing strains of lactic acid bacteria (LAB), Leuconostoc lactis A95 and Lactobacillus curvatus 69B2, were used as starters. Immature flour contained 2.21 g/100 g (dry weight) of fructo-oligosaccharides. Twenty percent immature flour in dough resulted in a shorter leavening time (4.23 � 0.03 h) than with the control and dough with 10% immature flour. The total titratable acidity of sourdough with 20% immature flour was higher (12.75 � 0.15 ml 0.1 N NaOH) than in the control and sourdough with 10% immature wheat flour (9.20 ml 0.1 N NaOH). Molecular analysis showed that all samples contained three LAB species identified as L. lactis, L. curvatus, and Pediococcus acidilactici. A larger amount of exopolysaccharide was found in sourdough obtained with 20% immature flour (5.33 � 0.032 g/kg), positively influencing the exopolysaccharide content of the bread prepared by the sourdough process (1.70 � 0.03 g/kg). The addition of 20% immature flour also led to a greater presence of fructo-oligosaccharides in the bread (900 mg/100 g dry weight), which improved its nutritional characteristics. While bread volume decreased as the concentration of immature wheat flour increased, its mechanical characteristics (stress at a strain of 30%) were the same in all samples obtained with different percentages of fructo-oligosaccharides. These data support the use of immature wheat grain flour, and exopolysaccaride-producing lactic acid bacteria in formulating functional prebiotic baked goods whose nutritional value can be suitably improved.

Responses to ozone pollution of alfalfa exposed to increasing salinity levels.

Stomatal closure and biosynthesis of antioxidant molecules are two fundamental components of the physiological machinery that lead to stress adaptation during plants exposure to salinity. Since high stomatal resistance may also contribute in counteracting O(3) damages, we hypothesized that soil salinization may increase O(3) tolerance of crops. An experiment was performed with alfalfa grown in filtered (AOT40=0 in both years) and non-filtered (AOT40=9.7 in 2005 and 6.9 ppm h in 2006) open-top chambers. Alfalfa yield was reduced by O(3) (-33%) only in plants irrigated with salt-free water, while the increasing levels of soil salinity until 1.06 dS m(-1) reduced both stomatal conductance and plant O(3) uptake, thus linearly reducing O(3) effects on yield. Therefore a reliable flux-based model for assessing the effects of O(3) on crop yield should take into account soil salinity.

Durum Wheat in Conventional and Organic Farming: Yield Amount and Pasta Quality in Southern Italy

Five durum wheat cultivars were grown in a Mediterranean area (Southern Italy) under conventional and organic farming with the aim to evaluate agronomic, technological, sensory, and sanitary quality of grains and pasta. The cultivar Matt produced the best pasta quality under conventional cropping system, while the quality parameters evaluated were unsatisfactory under organic farming. The cultivar Saragolla showed the best yield amount and pasta quality in all the experimental conditions, thus proving to be the cultivar more adapt to organic farming. In all the tested experimental conditions, nivalenol (NIV) and deoxynivalenol (DON) occurrence was very low and the other mycotoxins evaluated were completely absent. These data confirm the low risk of mycotoxin contamination in the Mediterranean climate conditions. Finally, it has been possible to produce high-quality pasta in Southern Italy from durum wheat grown both in conventional and organic farming.

Comparative attributional life cycle assessment of annual and perennial lignocellulosic feedstocks production under Mediterranean climate for biorefinery framework

Annual fiber sorghum (FS) and perennial giant reed (GR) cultivated in the Mediterranean area are interesting due to their high productivity under drought conditions and their potential use as lignocellulosic feedstock for biorefinery purposes. This study compares environmental constraints related to FS and GR produced on experimental farms (in the Campania region) using an attributional life cycle assessment (LCA) approach through appropriate modeling of the perennial cultivation. For both crops, primary data were available for agricultural management. Direct field emissions (DFEs) were computed, including the potential soil carbon storage (SCS). Giant reed showed the lowest burdens for all impact categories analyzed (most were in the range of 40%-80% of FS values). More apparent were the differences for climate change and freshwater eutrophication (respectively 80% and 81% lower for GR compared to FS). These results are due to the short-term SCS, experimentally detected in the perennial GR crop (about 0.25 ton C ha(-1) yr(-1), with a global warming offsetting potential of about 0.03 ton CO2/ton(GR dry biomass)). The results are also due to the annual application of triple superphosphate at the sowing fertilization phase for FS, which occurs differently than it does for GR. Phosphorous fertilization was performed only when crops were being established and therefore properly spread along the overall crop lifetime. For both crops, after normalization, terrestrial acidification and particulate matter formation were relevant impact categories, as a consequence of the NH3 DFE by volatilization after urea were spread superficially. Therefore, the results suggest higher environmental benefits of the perennial crop than the annual crop.

Plant and soil resistance to water flow in faba bean (Vicia faba L. major Harz.)

An experiment was conducted to determine soil and plant resistance to water flow in faba bean under field conditions during the growing season. During each sampling period transpiration flux and leaf water potential measured hourly were used with daily measurements of root and soil water potential to calculate total resistance using Ohms law analogy. Plant growth, root density and soil water content distributions with depth were measured. Leaf area and root length per plant reached their maximum value during flowering and pod setting (0.31 m2 and 2200 m, respectively), then decreasing until the end of the growing period. Root distribution decreased with depth ranging, on average, between 34.2% (in the 0–0.25 m soil layer) and 18.1% (in the 0.75–1.0 m soil layer). Mean root diameter was 0.6 mm but most of the roots were less than 0.7 mm in diameter. Changes in plant and soil water potentials reflected plant growth characteristics and climatic patterns. The overall relationship between the difference in water potential between soil and leaf and transpiration was linear, with the slope equal to average plant resistance (0.0165 MPa/(cm3 m-1 h-1 10-3). Different regression parameters were obtained for the various measurement days. The water potential difference was inversely related to transpiration at high leaf stomatal resistance and at high values of VPD. Total resistance decreased with transpiration flux in a linear relationship (r=−0.68). Different slope values were obtained for the different measurement days. Estimated soil resistance was much lower than the observed total resistance to water flow. The change from vegetative growth to pod filling was accompanied by an increase in plant resistance. The experimental results support previous findings that resistance to water flow through plants is not constant but is influenced by plant age, growth stage and environmental conditions. A more complex model than Ohms law analogy may be necessary for describing the dynamic flow system under field conditions.

The hemicellulose extract from Cynara cardunculus: a source of value-added biomolecules produced by xylanolytic thermozymes

The Cynara cardunculus hemicellulose fraction was recovered from its stem and leaf biomass and converted into valuable molecules by exploiting the extracellular xylanase and β-xylosidase activities produced by the thermophilic bacterium Geobacillus thermantarcticus. Several degradation procedures for the arabinoglucuronoxylan extract were proposed by using efficient and different enzymatic preparations, containing both or only one xylanolytic activity of G. thermantarcticus. In particular, when the xylanase and β-xylosidase activities were used separately in hydrolysis reactions, xyloglucurono-oligosaccharides or xylose were obtained with a yield of 32% and 62.6% respectively, with reference to the hemicellulosic extract. Furthermore, the synergic action of β-xylosidase/xylanase activities was exploited in transglycosylation processes for the production of xylo-conjugated compounds; xylosides of primary alcohols with increasing carbon chains and aromatic alcohols were produced starting from the C. cardunculus hemicellulose, which was selected as a cheap donor. When 2-phenoxyethanol was selected as an acceptor, 2-phenoxyethyl β-xyloside, xylobioside and xylotrioside were prepared with a yield of 38.5% with respect to the hemicellulosic extract and spectroscopically characterized.

Tropospheric ozone effects on chemical composition and decomposition rate of Quercus ilex L. leaves

We determined the effects of tropospheric ozone on the chemical composition of Quercus ilex L. leaves and their decomposition, with a view to assessing the influence of ozone on nutrient cycling and the sustainability of Mediterranean holm oak forests. Forming one of the most widespread thermophilous vegetation communities in the area, Q. ilex is a dominant and widespread evergreen oak in the Mediterranean, where concentrations of tropospheric ozone are particularly high. The dynamics of carbon, nitrogen, lignin and cellulose concentrations were monitored for six months during the decomposition of leaves from plants subjected to controlled ozone exposure in open-top chambers. Ozone-exposed leaves, compared to unexposed leaves, showed no significant differences in C, N, lignin and cellulose concentrations prior to the incubation in mesocosms. However, during decomposition, leaves from plants exposed to ozone lost C significantly more slowly and showed a higher C/N ratio than unexposed leaves. Ozone exposure significantly slowed down the decomposition rate, indicating a negative effect of tropospheric ozone on nutrient cycling, which may reduce long-term sustainability of the holm oak forest.

Response to salinity stress of Rhizobium leguminosarum bv. viciae strains in the presence of different legume host plants

We investigated the effect of residual salts from the previous summer’s irrigation on two non-irrigated cover crops—broad bean and common vetch—and on their rhizobial symbiontics. Before sowing, seeds were inoculated with a salt-tolerant strain and a salt-sensitive strain of Rhizobium leguminosarum biovar viciae. An increase in the electrical conductivity of the saturated-soil extract from 2.0 dS m−1 to 6.0 dS m−1 caused a severe reduction of broad bean biomass, while growth of common vetch was almost unaffected by the salinity level. Our results clearly indicate that common vetch as a cover crop may increase the availability of nitrogen in soil more than broad bean also in saline environments. A high ability of both inoculated strains to nodulate Vicia plants was observed under controlled conditions. In contrast, inoculated strains were not able to nodulate plants in salinized soils, showing lower competitiveness compared to natural rhizobial population. Indeed, the new isolates from nodules were salt-sensitive when tested in vitro. The complex interaction among bacteria, plant and soil determined the survival of endogenous salt sensitive rhizobial strains and limited the success of inoculation with exogenous salt resistant rhizobia.

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

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