Concetta Vazzana

Evaluation of sustainability of organic, integrated and conventional farming systems: a farm and field-scale analysis

Abstract Agricultural researchers widely recognise the importance of sustainable agricultural production systems and the need to develop appropriate methods to measure sustainability. The principal purpose of this paper is to evaluate the financial and environmental aspects of sustainability of organic, integrated and conventional farming systems (OFS, IFS and CFS, respectively) at farm level and on more detailed spatial scales. This was achieved by applying an integrated economic-environmental accounting framework to three case study farms in Tuscany (Italy) covering different farming systems (FSs) and different spatial scales. The environmental performances of the FSs were measured through the application of an environmental accounting information system (EAIS) at field, site and farm level. The EAIS indicators were then integrated with: (1) a set of financial indicators to evaluate the economic and environmental trade-offs between different FSs and (2) with information on the regional and site-specific soil and climate conditions to study the impact of different pedo-climates on the environmental performances of the FSs. The gross margins of steady-state OFSs were found to be higher than the corresponding CFS gross margins. The OFSs perform better than IFSs and CFSs with respect to nitrogen losses, pesticide risk, herbaceous plant biodiversity and most of the other environmental indicators. However, on hilly soils, erosion was found to be higher in OFSs than in CFSs. The pesticide and the nitrogen indicators in this study showed a similar environmental impact caused by integrated and conventional farming practices. Regional pedo-climatic factors were found to have a considerable impact on nutrient losses, soil erosion, pesticide risk and herbaceous plant biodiversity, site-specific factors on nutrient losses and soil erosion. Results at field level suggest that herbaceous plant biodiversity and crop production are not always conflicting variables. Results of the case study farms are discussed and compared with environmental sustainability thresholds reported from EU Directives on nitrate and pesticides in groundwater and the literature.

Morphological and ultrastructural aspects of dehydration and rehydration in leaves of Sporobolus stapfianus

The resurrection species Sporobolus stapfianus Gandoger has been studied by LM, TEM and SEM in order to define the leaf morphology and fine structure and to analyse the cellular changes occurring during the processes of dehydration and rehydration of the plant. Some characteristics of the fully hydrated leaf and some ultrastructural and physiological events which take place during leaf wilting are discussed in relation to their possible role in plant desiccation-tolerance.The leaves of S. stapfianus show several characteristics common among xerophytic species. In the resurrection leaf they could play a role in slowing down the drying rate, thus leaving time to activate the mechanisms protecting the cell structures against drought damage. Actually, the S. stapfianus leaves do not undergo important cellular alterations during dehydration. The chloroplasts, in particular, retain part of their photosynthetic pigments and thylakoid membranes. Upon rewatering leaf recovery is rather fast and the tissue structure and cell organization of the fully hydrated state are already regained after two days.

Changes of low-molecular weight substances in boea hygroscopica in response to desiccation and rehydration

Abstract Boea hygroscopica is a poikilohydrous plant. This and similar species are also called desiccation-tolerant or resurrection plants. They have the unique ability to revive from an extreme air-dry condition. Samples of fresh, dried and rehydrated leaves were analysed for the major classes of organic substances like sugars, alditols, inositols, fatty acids, amino acids, betaines, phytosterols and others. The compounds which accumulated in desiccated leaves were sucrose and polyunsaturated C 18 acids. Abietanes and pimaranes were also detected. Monosaccharides, which are present in fresh leaves, disappeared, whilst phytosterols, stearic and oleic acids decreased to low levels; paimitic acid was unchanged. Rehydration of dried leaves seemed to restore the chemical composition of unstressed leaves. Betaines were not detected in any of the plant samples examined.

Mycorrhizal activity and diversity in a long-term organic Mediterranean agroecosystem

In organic agriculture, soil fertility and productivity rely on biological processes carried out by soil microbes, which represent the key elements of agroecosystem functioning. Arbuscular mycorrhizal fungi (AMF), fundamental microorganisms for soil fertility, plant nutrition and health, may play an important role in organic agriculture by compensating for the reduced use of fertilizers and pesticides. Though, AMF activity and diversity following conversion from conventional to organic farming are poorly investigated. Here we studied AMF abundance, diversity and activity in short- and long-term organically and conventionally managed Mediterranean arable agroecosystems. Our results show that both AMF population activity, as assessed by the mycorrhizal inoculum potential (MIP) assay, the percentage of colonized root length of the field crop (maize) and glomalin-related soil protein (GRSP) content were higher in organically managed fields and increased with time since transition to organic farming. Here, we showed an increase of GRSP content in arable organic systems and a strong correlation with soil MIP values. The analysis of AMF spores showed differences among communities of the three microagroecosystems in terms of species richness and composition as suggested by a multivariate analysis. All our data indicate that AMF respond positively to the transition to organic farming by a progressive enhancement of their activity that seems independent from the species richness of the AMF communities. Our study contributes to the understanding of the effects of agricultural managements on AMF, which represent a promising tool for the implementation of sustainable agriculture.

Drought stress effects on three cultivars of Eragrostis curvula: photosynthesis and water relations

Water stress effects were studied on three cultivars ofEragrostis curvula. Leaf water potential, RWC, total plantleaf area, green dry weight mass percentage and CO2 gas-exchangeweremeasured during the onset of stress and after recovery. After 3 days of waterstress, RWC of cv Tanganyika plants was around 30–40% of controls,while RWC of cvs Ermelo and Consol was around 50–60% of controls.However midday and predawn water potentials were lower in cvs Tanganyka andErmelo than in cv Consol. After re-watering, RWC and water potentials recoveredonly in Consol plants. A strong decrease of leaf area was recorded in cvsErmeloand Consol during water stress (about 91–94% less than the leafarea of controls). Photosynthesis decreased as a function of the degree ofwaterstress severity in all cultivars. Also, light saturated photosynthesis,CO2 quantum yield and light at which saturated photosynthesisoccurred, were strongly reduced by water stress. Recovery of photosynthesis wasfound in cv Consol after five days re-watering. Cv Consol showed a betterconservation of water and higher resistance to water stress than the other twocvs.

Effects of Short-Term Consumption of Bread Obtained by an Old Italian Grain Variety on Lipid, Inflammatory, and Hemorheological Variables: An Intervention Study

The aim of this study was to evaluate the influence of short-term dietary intake of bread obtained by a selected variety of old grain grown in Tuscany, Italy on some parameters related to the atherosclerotic process. Twenty healthy subjects (median age, 39.5 years) followed for 10 weeks a diet containing bread (150 g/day) made from the test grain (test period) and for the same period a diet containing commercially available bread of the same quantity (control period). Lipid, inflammatory, and hemorheological profiles before and after dietary intervention were evaluated. The test period showed a significant (P < .05) improvement of total cholesterol (pre-intervention, 211.2 +/- 10.8 mg/dL; post-intervention, 196.5 +/- 9.8 mg/dL) and low-density lipoprotein-cholesterol levels (pre-intervention, 137.5 +/- 8.1 mg/dL; post-intervention, 119.5 +/- 7.5 mg/dL), whereas no significant changes during the control period were observed. With regard to inflammatory and hemorheological parameters, the test period showed a significant decrease in some of the parameters investigated (interleukin-8 [pre-intervention vs. post-intervention, 67.4 +/- 10.7 vs. 43.9 +/- 4.1 pg/mL], whole blood viscosity at high [4.36 +/- 0.03 vs. 4.32 +/- 0.03 mPa x s, respectively] and low [26.1 +/- 0.4 vs. 24.8 +/- 0.5 mPa x s, respectively] shear rates, and erythrocyte filtration [8.4 +/- 0.7% vs. 9.1 +/- 0.6%, respectively]) relative to the control period, which showed no significant changes. Short-term dietary intake of whole grain bread obtained from an old grain variety seems to impose a favorable status with regard to lower circulating levels of markers of atherosclerosis.

Galactinol in the leaves of the resurrection plant Boea hygroscopica

Abstract The content of low molecular weight substances was analysed in leaf samples of the resurrection plant Boea hygroscopica F. Muell. submitted to dehydration. Drying treatment caused a variation in the carbohydrate pool, with a decrease of all sugars except sucrose which notably increased, becoming the prevalent one in dried leaves. Rehydration almost restored the pre-treatment sugar composition. Along with more common sugars galactinol and some higher oligosaccharides of the raffinose family were detected. Their structures were assigned by NMR and GC–MS analyses after acetylation. To our knowledge, this is the first finding in resurrection plants of significant amounts of the galactosyl donor galactinol and of higher galactosyl oligosaccharides, which may have a role in restoring the pre-drying functions upon rehydration.

The use of ultrasound technique to monitor freezing and thawing of water in plants

Abstract In this paper, the relationship between acoustic emission and freezing and thawing of plant tissues is investigated by means of ultrasound techniques. Ultrasound pulses were detected only after freezing. Ultrasound pulses of well-watered plants are negligible before the occurrence of freezing events that usually appear below −4°C. Temperature lowering after freezing determines a sharp increase in ultrasound emission. The relationship between acoustic emission and the dehydration process caused by extracellular ice is discussed. From the preliminary observations reported, the ultrasound technique seems to be a useful tool for evaluating the occurrence of freezing stress in woody plants.

Desiccation Tolerance in Immature Embryos of Maize: Sucrose, Raffinose and the ABA—Sucrose Relation

Our previous experiments on desiccation tolerance in immature embryos of maize cast doubt on a crucial role of high concentrations of sucrose and high raffinose to sucrose mass ratio. In the present work we report experiments aimed at gaining a further insight into the above mentioned subject and to ascertain whether endogenous ABA may stimulate the accumulation of sucrose. Immature and desiccation sensitive embryos of maize were isolated and exposed to different drying conditions either leading or not leading to desiccation tolerance acquisition and allowing for different ABA and sugar responses. ABA concentrations as well as sugar concentrations were compared in embryos undergoing such different dehydration treatments. We conclude that in maize embryos: 1) sucrose, even at high concentrations, is not the sole factor responsible for desiccation tolerance; 2) high sucrose concentrations do not appear to be an absolute requirement of desiccation tolerance; 3) a high (>0.05) raffinose to sucrose mass ratio is not a prerequisite of desiccation tolerance; 4) ABA doesn’t seem to stimulate sucrose accumulation. We suggest that desiccation tolerance can occur even in the absence of raffinose.

Moisture content of the dried leaf is critical to desiccation tolerance in detached leaves of the resurrection plant Boea hygroscopica

In our experimental conditions detached leaves of the resurrection plant Boea hygroscopica survived equilibration to 65–80% RH (Relative Humidity), but not to very low RH (close to 0%). The first aim of our research was to determine whether sensitivity to equilibration to very low RH depends on the rate of the drying process or on the very low final MC (Moisture Content) attained. The second aim of our research was to determine ABA content of leaves exposed to the two drying processes: a first step towards understanding whether ABA is involved in the tolerance mechanism of Boea hygroscopica.Detached leaves were equilibrated either to 1.4 or to 60–70% RH or to various temporal combinations of these two RH. ABA content was monitored during drying. Dehydrated leaves were imbibed in liquid water either directly or after a slow rehydration at 98% RH. Tolerance was assessed after 48 h imbibition in liquid water.The low final MC attained (about 3%) and not the rate of drying was responsible of the sensitivity of leaves equilibrated to 1.4% RH. Slow rehydration attained better recovery, but it was not able to allow full “resurrection” thus suggesting that a plain biophysical liquid-crystalline to gel phase transition of the membrane lipid bilayer could not fully account for the lethal damage of the very low MC.The conclusions relative to the first part of our research was of primary importance in interpreting results concerning ABA variations during the two drying treatments. ABA showed a very similar transient increase when excised leaves were dried at either 1.4% RH (sensitive leaves) or at 60–70% RH (tolerant leaves). However we cannot exclude that the transient increase of the hormone is a necessary component of the desiccation tolerance mechanisms in detached leaves of Boea hygroscopica: the extremely low MC reached by equilibration to 1.4% RH may impair the mechanism itself.