RESUMO
To measure gas exchange at the whole plant (WP) level, design solutions were provided and prototypes of gas-exchange systems (GESs) were tested to carry out shoot and rootzone analyses in plants of different sizes. A WP-GES for small herbaceous plants was tested on the ability to maximize the net assimilation rate of CO2 in lettuce plants grown either under blue-red light or upon full spectrum artificial light. A WP-GES for large woody plants was tested during an experiment describing the drought stress inhibition of grapevine transpiration and photosynthesis. Technical advances pointed to optimize: i) the choice of cuvette material and its technical configuration to allow hermetic isolation of the interface shoot-rootzone, to avoid contamination between the two compartments, and to allow climate control of both shoot and rootzone cuvettes, ii) accurate measurements of the mass air-flow entering both cuvettes, and iii) an adequate homogenization of the cuvette air volume for stable and accurate detection of CO2 and H2O concentration in cuvettes before and after CO2 and H2O contamination of the air volumes exerted by plant organs.
Assuntos
Dióxido de Carbono , Folhas de Planta , Folhas de Planta/fisiologia , Água/fisiologia , Fotossíntese/fisiologia , PlantasRESUMO
To understand how grapevine sinks compete with each other during water stress and subsequent rehydration, carbon (C) allocation patterns in drought-rehydrated vines (REC) at the beginning of fruit ripening were compared with control vines maintained under drought (WS) or fully irrigated (WW). In the 30 days following rehydration, the quantity and distribution of newly fixed C between leaves, roots and fruits was evaluated through 13 CO2 pulse-labeling and stable isotope ratio mass spectrometry. REC plants diverted the same percentage of fixed C towards the berries as the WS plants, although the percentage was higher than that of WW plants. Net photosynthesis (measured simultaneously with root respiration in a multichamber system for analysis of gas exchange above- and below-ground) was approximately two-fold greater in REC compared to WS treatment, and comparable or even higher than in WW plants. Maximizing C assimilation and delivery in REC plants led to a significantly higher amount of newly fixed C compared to both control treatments, already 2 days after rehydration in root, and 2 days later in the berries, in line with the expression of genes responsible for sugar metabolism. In REC plants, the increase in C assimilation was able to support the requests of the sinks during fruit ripening, without affecting the reserves, as was the case in WS. These mechanisms clarify what is experienced in fruit crops, when occasional rain or irrigation events are more effective in determining sugar delivery towards fruits, rather than constant and satisfactory water availabilities.
Assuntos
Secas , Vitis , Frutas/metabolismo , Vitis/genética , Vitis/metabolismo , Fotossíntese , Folhas de Planta/metabolismo , Açúcares/metabolismoRESUMO
Abstract Digitalised supply-chain traceability systems can offer wide prospects both for improving safety as well as enhancing perceived quality [...].
Assuntos
Dispositivo de Identificação por Radiofrequência , CarneRESUMO
Particulate matter (PM) is an air pollutant which poses a considerable risk to human health. The agricultural sector is responsible of the 15% of the total anthropogenic emissions of PM10 (PM fraction with aerodynamic diameter below 10 µm) and soil preparation activities have been recognized as one of the main drivers of this contribution. The emission factors (EF) proposed by European environmental agency (EEA) for tilling operations are based on very few studies, none of which has been made in Italy. Moreover, few studies have considered the influence of operative parameters on PM10 emissions during tilling. The aim of this work was to assess PM10 emission and dispersion during rotary harrowing and to understand how operative parameters, such as forward speed and implement choice may affect PM release. A further objective was to assess the near field dispersion of PM10 to address exposure risks. Emission factors (EFs) were determined during two different trials (T1 and T2). During T1, the effect of tractor speeds (0.6, 1.1 and 1.7 m s-1) on PM10 emissions was investigated, while in T2 a comparative essay was made to study the influence of levelling bar height on emissions. The average ground level downwind concentrations of PM10 during harrowing operation was estimated through dispersion modelling. The observed PM10 EFs for rotary harrowing were 8.9 ± 2.0 mg m-2 and 9.5 ± 2.5 mg m-2 on T1 and T2, respectively. The heavy metal content of soil-generated PM10 was also assessed. In the generated PM, the elemental concentrations were higher than ones in soil. As, Cd and Ni concentration levels, determined in PM10 near to the tractor path, were also high, being several times higher than the annual average regulatory threshold levels in ambient air, as defined by the European regulation.
Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/análise , Agricultura , Monitoramento Ambiental , Humanos , Itália , Tamanho da Partícula , Material Particulado/análiseRESUMO
Electrolyzed water (EW) has attracted much recent attention as a high-performance, new technology for its potential use in the food industry. However, the risk of postharvest EW treatments of winegrapes destined for winemaking is the chloroanisoles formation in the final product. In the present study, we investigated the impact of postharvest grape EW and storage treatments on the occurrence of these compounds in wine, 2,4,6-trichloroanisole (TCA) being the main compound responsible for the cork taint off-flavor due to its extremely low perception threshold. The results revealed that the presence of TCA in the wines depended on the concentration of residual free chlorine in the must from the EW treatment. Particularly, TCA was not detected in wine when active chlorine concentrations higher than 0.005â¯mg/L were present in the must. Chloroanisole and chlorophenol levels in wine were strongly affected not only by EW but also by grape storage conditions (temperature, time, sunlight exposition). The results showed that the 24-hours grape storage at a controlled temperature of 20⯰C in the dark, after EW treatment, resulted in the highest TCA concentrations in wines (7.3⯱â¯2.7â¯ng/L), while storage and withering in sunlight seemed to mitigate its presence in wine. This could suggest that microbiological formation of chloroanisoles may have been influenced by the storage temperature and germicidal effect of UV light. Biochemical mechanism of chloroanisoles production in grapes and wine is unknown, but the combination of residual free chlorine on the grape surface and the controlled storage conditions in the dark may have positively influenced the bio-formation of chloroanisoles and therefore their presence in wine.
Assuntos
Contaminação de Alimentos/análise , Manipulação de Alimentos , Água/química , Vinho/análise , Anisóis/análise , Cloro/análise , Clorofenóis/análise , Eletrólise , Fermentação , Análise de Alimentos , Microbiologia de Alimentos , Armazenamento de Alimentos , Percepção , Limiar Sensorial , Luz Solar , Paladar , Percepção Gustatória , Temperatura , Vitis/químicaRESUMO
This study was performed to evaluate and compare the effects of different pre-treatments of whole grape berries (freezing with dry ice or in a cold room, steam blanching with different exposure times, and microwave heating with different exposure times and microwave power density) on total content of some phenolic compounds and the composition of individual anthocyanins released into the pulp during the treatment and those extracted during the maceration step. Two red winegrape varieties with different proportions of di- and trisubstituted anthocyanins were used (Nebbiolo and Barbera, respectively). Pulp-extracted anthocyanins were more significantly influenced by the pre-treatment. The results highlighted that freezing with dry ice, followed by freezing in a cold room and steam blanching for 5 min, have a great potential from an industrial point of view. They facilitated the extraction of anthocyanins in the must prior to maceration, when compared with the control samples, increasing their total content (+37.8-83.6%), and modifying the anthocyanin profile through the enrichment in the most stable compounds (+2.8-6.6% malvidin derivatives) to the detriment of others more prone to oxidation (-0.8-11.0% cyanidin derivatives). In Nebbiolo winegrapes, an improved extraction of low- and high-molecular weight flavanols into the pulp was also observed (+60.4-73.4%). Significant relationships between the phenolic composition of treated berries and the corresponding skin mechanical properties were also studied, but they were variety dependent. Discriminant analysis permitted a correct classification of the samples according to the variety and pre-treatment.