Abstract:The aims of this study were to evaluate: (1) the effect of sodium chloride (NaCl) and mannitol at different osmotic pressures on the germination of three proso millet (Panicum miliaceum L.) genotypes (VIR 9181, Unikum, and Kinelskoje) under controlled laboratory conditions; and (2) the effects of irrigation water salinity, maximum crop evapotranspiration (ETm) restitution regimes, and arbuscular mycorrhizal fungi (AMF) inoculation on forage production in a marginal Mediterranean soil for the genotypes that showed the highest and lowest seed germination. In the laboratory experiment, the Unikum genotype showed the highest seed germination (95.1%), whereas the lowest was found for Kinelskoje (80.4%). Regardless of the osmoticum type, germination was significantly reduced by osmotic pressure increases. Unikum showed a higher fresh biomass yield (FBY) (620.4 ± 126.3 g m −2 ) than Kinelskoje (340.0 ± 73.5 g m −2 ). AMF inoculation did not influence FBY under salt conditions, while in the absence of salt conditions it significantly increased the Unikum FBY (+50.7%) as compared to the uninoculated treatment (552.5 ± 269 g m −2 ). The 25% ETm significantly reduced FBY in both genotypes (−86.2% and −84.1% for Unikum and Kinelskoje, respectively) sd compared to the 100% ETm treatments (1090.3 ± 49.7 g m −2 in Unikum and 587 ± 72.2 g m −2 in Kinelskoje). The obtained results give novel information about proso millet forage production in low-input agriculture in marginal semi-arid Mediterranean land.

The aim of this study was to evaluate the agronomical and environmental effects of digestate solid fraction (DSF) used as fertilizer in a vegetable crop succession (green bean, savoy cabbage, cabbage and cauliflower) in North-East Italy (45°20’ N; 11°57’ E). Three fertilization treatments were tested using DSF to substitute 0% (Tmin), 50% (T50) and 100% (T100) optimal level of mineral nitrogen fertilization. The experiment was carried out from 22^nd May 2014 (green bean sowing) to 3^rd June 2015 (cabbage harvest). Summer and spring crops did not show significantly different marketable yield among fertilization treatments with an average value (±SE) of 9.0 ± 0.5, 9.9 ± 1.2 and 51.3 ± 6.4 Mg ha^-1 for green bean, cauliflower and cabbage, respectively. Lower DSF fertilization effect was monitored on winter crop (savoy cabbage) with a marketable yield reduction of -35.1% than mineral fertilization (25.9 Mg ha^–1) whereas the T50 treatment was not significantly different compared to the two previous ones. Crop species significantly influenced the N use efficiencies with negative recovery and use efficiency indexes for the DSF fertilization treatments. Soil CO2 emissions were not significantly influenced by fertilization in all studied crops with median values always lower than 1 g m^-2 h^-1.

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Abstract:With the aim at enhancing the sustainability of biomass production in the Mediterranean area, this paper analyzes, for the first time, the production of sorghum (Sorghum bicolor (L.) Moench) biomass for bioenergy production using urban treated wastewaters and bio-fertilization. For this purpose, the effects on biomass production of three different fertilizations (no-nitrogen control, biofertilizer, and mineral ammonium nitrate), four levels of constructed wetland (CW) wastewater restitutions (0%, 33%, 66% and 100%) of crop evapotranspiration (ETc) and three harvesting dates (at full plant maturity, at the initial senescence stage, and at the post-senescence stage) were evaluated in a two year trial. For bio-fertilization, a commercial product based on arbuscular mycorrhizal fungi was used. Mineral nitrogen (N) fertilization significantly increased dry biomass (+22.8% in the first year and +16.8% in the second year) compared to the control (95.9 and 188.2 g·plant −1 , respectively). The lowest and highest biomass production, in 2008 and 2009, was found at 0% (67.1 and 118.2 g·plant −1 ) and 100% (139.2 and 297.4 g·plant −1 ) ETc restitutions. In both years, the first harvest gave the highest biomass yield (124.3 g·plant −1 in the first year and 321.3 g·plant −1 in the second), followed by the second and the third one. The results showed that in Mediterranean areas, constructed wetlands treated wastewaters, when complying with the European restrictions for their use in agriculture, may represent an important tool to enhance and stabilize the biomass of energy crops by recycling scarce quality water and nutrients otherwise lost in the environment.