The frequency and the density of the species associated with grape sour rot in different cultivars were determined. The most frequent species in the rotten grapes, Candida krusei, Kloeckera apiculata, and Metschnikowia pulcheryima, and a less frequent species, Issatchenkia occidentalis, when inoculated with Saccharomycopsis crataegensis were able to induce in vitro the symptoms of the disease. The gas chromatographic determination of the volatile compounds in the headspace was used to evaluate the metabolic role of the different species associated with the disease. These analyses made it possible to presume that, whereas some species, such as Candida krusei and Hanseniaspora uvarum, can be considered responsible for these modifications and in particular for the ethyl acetate production, others, such as Saccharomycopsis crataegensis, can promote the development of the former species.

Fertilizer N excesses may have negative effects on both crop and water quality. To reduce the risk of N excesses it is essential to accurately define fertilizer N rates. The estimate of the most suitable N rate is complicated by the fact that a certain amount of the N taken up by the crop during the growth season is supplied by the soil. The aim of this work was to estimate the amount of N that can become available for plant uptake during the crop growth season. The effects of five N rates (0, 20, 40, 60, and 80 kg N ha 21 ) on production traits of flue-cured tobacco (Nicotiana tabacum L.) cv. K326, and on selected items of an N balance applied to the soil-plant system were studied on a loam soil, in 1998 and 1999, at Bovolone (Verona, northern Italy). The fertilizer N rate positively and significantly influenced cured-leaf yields only in 1999, whereas the time to harvest increased linearly for increasing N rates, in both years (0.25 d on average for every further kg of fertilizer N). The N balance indicated a remarkable reduction of the soil organic N stock and an increase of the soil inorganic N levels throughout the crop growth period. As these changes were both proportional to the fertilizer N rate, the occurrence of a positive priming effect was hypothesized. The formulation of N fertilizer recommendations to farmers should take into account the existence of priming effect phenomena.

In this study, the potential for biogas production from biodegradable bioplastics was evaluated. Mater-Bi ® (a family of maizestarch based flexible films) and PLA (PolyLactic Acid; a rigid, polylactide-based, polymer) bioplastics were digested in laboratory batch reactors, alone or in co-digestion with pig slurry or scotta (partially deproteinized cheese whey), at 35°C or 55°C. Methane (CH4) and hydrogen (H2) production were monitored during the incubation period. Maximum CH4 (Mmax) or H2 (Hmax) production per reactor, potential CH4 (BMP) or H2 (BHP) production g -1 volatile solids (VS), and residual VS in the digestates were determined. Methane was produced when bioplastics were digested alone or with pig slurry, whereas H2 was produced only in co-digestion with scotta. Mmax, BMP, Hmax and BHP were on average higher at 55°C than at 35°C (+69%, +158%, +51% and +45%, respectively). At 35°C, in monodigestion, small amounts of CH4 (33 mL g -1 VS) were produced with Mater-Bi ® only. At 55°C, the BMP for Mater-Bi® and for PLA were equal to 113 mL and 282 mL CH4 g -1 VS, respectively. Monodigestion of MaterBi ® and PLA at 55°C reduced the initial VS content by 51%. When PLA was in co-digestion with pig slurry, Mmax was 12% higher than the theoretical one, with a synergistic effect. In co-digestion with scotta, a nearly significant 12% increase in H2 production was observed for Mater-Bi ® incubated at 35°C. The exploitation of bioplastic waste in anaerobic digestion for biogas production, together with or in alternative to conventional composting, appears a promising possibility for a successful waste management.

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Experiments were designed to establish whether mercuric chloride administered to rainbow trout (Salmo gairdneri Rich.) through the gills or by way of the mouth is converted in vivo to methylmercury. The mercury was measured by atomic absorption spectrophotometry and methylmercury determinations were performed by extraction and gas chromatography. The experiments show that while mercuric chloride administered by either method increased the total mercury content of kidney, liver, intestine, and muscle tissues, no evidence was found to support the hypothesis that mercuric chloride was methylated in fish to form methylmercury.

The biogas production through the anaerobic digestion (AD) of giant reed (Arundo donax L.) biomass has received increasing attention. However, due to the presence of lignin, a low CH4 yield can be obtained. Aiming to improve the CH4 yield from giant reed biomass, the effectiveness of a thermo-chemical pre-treatment based on KOH was evaluated in this paper. The usefulness of a washing step before the AD was also assessed. The pre-treatment led to a specific CH4 yield up to 232 mL CH4 g−1 VS which was 21% higher than that from untreated biomass; the maximum daily rate of production was improved by 42%, AD duration was reduced by 10%, and CH4 concentration in the biogas was increased by 23%. On the contrary, the washing step did not improve the AD process. Besides, washing away the liquid fraction led to biomass losses, reducing the overall CH4 production. The use of a KOH-based pre-treatment appears as a good option for enhancing the AD of giant reed, also presenting potential environmental and agronomical benefits, like the avoidance of salty wastewater production and the likely improvement of the digestate quality, due to its enriched K content.