Lorenzo Barbanti

The contribution of switchgrass in reducing GHG emissions

The contribution of switchgrass (Panicum virgatum L.), a perennial C4 grass, in reducing greenhouse gas (GHG) emissions was reviewed under three main areas; the impact on carbon dioxide (CO2), nitrous oxide (N2O), and methane emissions (CH4), whilst also taking into account the effects of land conversion to switchgrass. Switchgrass is able to enhance biomass accumulation in a wide range of environmental conditions, which is the premise for considerable carbon assimilation and storage in the belowground organs. The progress in some areas of crop husbandry (e.g., tillage and fertilization) has fostered benefits for carbon storage, while restraining GHG emissions. As root biomass is the main indicator of soil carbon sequestration, switchgrasss dense and deep rooting is a relevant advantage, although uncertainty still exists about the crops belowground biomass accumulation. In agreement with this, most LCA studies addressing CO2 emissions report significant benefits from switchgrass cultivation and processing. Beside CO2, switchgrass performed better than most other biomass crops also in terms of N2O emission. In the case of CH4 emission, it may be argued that switchgrass should act as a moderate sink, i.e., contributing to mitigate CH4 atmospheric concentration, but a substantial lack of information indicates the need for specific research on the topic. Land conversion to switchgrass is the latest issue which needs to be addressed in LCA studies: not surprisingly, the net CO2 abatement appears remarkable if switchgrass is grown in former arable lands, although it is slightly negative to positive if switchgrass replaces permanent grassland. In conclusion, switchgrass could significantly contribute to mitigate GHG emissions, although areas of uncertainty still exist in the assessment of soil carbon storage, N2O and CH4 emissions, and the effects of converting lands to switchgrass. Further improvements must, therefore, be achieved to strengthen the crops remarkable sustainability.

Effects of hydrothermal pre-treatments on Giant reed (Arundo donax) methane yield

Twelve hydrothermal pre-treatment combinations of temperature (150 and 180 °C), time (10 and 20 min) and acid catalyst (no catalyst; H2SO4 at 2% w/w immediately before steam cooking or in 24-h pre-soaking) were tested to assess their effects on methane yield of Giant reed biomass vs. untreated control. A batch anaerobic digestion was conducted with 4 g VS l(-1) at 53 °C for 39 days. Untreated biomass exhibited a potential CH4 yield of 273 ml g(-1) VS; the four pre-treatments without acid catalyst achieved a 10%, 7%, 23% and 4% yield gain in the respective temperature/time combinations 150 °C/10 min, 150 °C/20 min, 180 °C/10 min and 180 °C/20 min. Conversely, the eight pre-treatments with H2SO4 catalyst incurred a methanogenic inhibition in association with high SO4(2-) concentration in the hydrolysate, known to enhance sulphate reducing bacteria. Furfurals were also detected in the hydrolysate of five strong pre-treatments with H2SO4 catalyst.

Late harvest associated with P and S fertilization enhances yield and quality of forage sorghum (Sorghum bicolor (L.) Moench), grown as a rainfed crop in Pakistan

-1 ), in combination with three levels of sulphur (0, 20 and 40 kg SO 4 ha -1 ), in combination with three harvest times (35, 45 and 55 days after emergence; DAE), were tested in a factorial randomized block design. At each harvest, morphological, functional, yield and quality traits were assessed on plant samples. Extending the growing season from DAE 35 to 55 enhanced almost all the traits and greatly benefited dry biomass yield (ca. +100%). The longer growth also determined a higher efficiency in the accumulation of dry biomass per unit time and land surface (crop growth rate ca. +30%), as well as per unit time and leaf surface (net assimilation rate ca. +100%). Quality traits also improved when plants were harvested at a more advanced maturity: leaf hydrocyanic acid content, a toxic component to livestock, decreased by ca. 30%; stalk soluble-solid content, an indicator of forage juiciness and palatability, increased by ca. 50%. On concluding, the combined effects of harvest delay, P and S fertilization on sorghum are deemed able to significantly increase forage production in warm, relatively dry areas of the world.

Chemical Composition and Antimicrobial Activity of Essential Oils from Aerial Parts of Monarda didyma and Monarda fistulosa Cultivated in Italy

Abstract Monarda spp. are promising Lamiaceae due to essential oil (EO) composition and antimicrobial activity. To investigate these properties, Monarda didyma and M. fistulosa were grown for two years in two Italian sites for EO extraction (distillation), analysis (GC and GC/MS), and antimicrobial activity (microplate diffusion broth method). EO yield greatly increased from first to second year of cultivation (0.27 and 0.51% in 2013 and 2014, respectively), showing minor differences between M. didyma and M. fistulosa. Conversely, EO composition significantly varied between the two species and years. Of the fifteen major compounds identified, eight were shared by the two species. However, the amounts differed, especially in thymol (62 vs. 31% in M. didyma vs. M. fistulosa) opposed to α- and β-phellandrene (their average, 1% in M. didyma and 16% in M. fistulosa). An increase of thymol was observed between 2013 and 2014 in both species (average, +11%), reflecting juvenile plants showing only vegetative organs (2013) vs. fully flowered plants (2014). Despite such differences, EO’s from the two Monarda species exhibited a similar activity against pathogenic and non-pathogenic strains of fungi and bacteria from human, animal and plant source. In general, Monarda EO’s showed a lower minimum inhibitory concentration, i.e. a stronger activity, against pathogenic (Escherichia coli, Erwinia amylovora and Candida albicans) than beneficial microorganisms (Bifidobacterium animalis and Lactobacillus casei). The higher susceptibility of pathogenic microorganisms supports the use of Monarda EO’s as antimicrobial agents with a favourable profile of selectivity. Applications are envisaged in food preservation, plant protection and human health.

Assessing Essential Oil Composition of Various Lamiaceae Accessions in View of Most Suitable Uses

Abstract Assessing the intra-specific variation in essential oil (EO) composition is the best premise for most suitable uses. In this frame, eight varieties of lavender (Lavandula officinalis), six genotypes of rosemary (Rosmarinus officinalis), and three genotypes of thyme (Thymus capitatus and T. cedrinus), grown at the same station in Northern Italy, were subjected to EO extraction (distillation) and analysis (gas chromatography/mass spectrometry). A wide range of EO yield was observed in lavender (from 0.42 to 1.07%), rosemary (from 0.10 to 0.89%), and thyme (from 0.03 to 0.11%). In lavender, several of the tested cultivars passed the AFNOR thresholds for either limonene, 1,8-cineole, camphor, linalool and linalyl acetate. However, this variation may be considered a resource more than a limitation, as a wider spectrum of potential uses can be addressed. In rosemary, main components also showing a relevant variation were α-pinene, 1,8- cineole and camphor, resulting in EO’s with different potential uses (from anti-bacterial to human health). Lastly, differences in thymol vs. geraniol and geranyl acetate among thyme genotypes were remarkable, once more indicating potentially different uses. In the three herbs, EO constituents were also grouped in compound classes and expressed in terms of yields (i.e., EO yield × compound class content). This quantitative assessment of EO characteristics allows producers to choose the most suitable accession to grow, in order to enhance the amount of recoverable compounds. Lastly, a principal component analysis of EO constituents was proved able to reduce EO complexity, while retaining the fundamental information concerning genotype similarity/divergence.

Data on seed germination using LED versus fluorescent light under growth chamber conditions

The present investigation attempted to assess the influence of two light sources, LED versus fluorescent light, on seed germination of nine aromatic species belonging to the genus Artemisia, Atriplex, Chenopodium, Salicornia, Sanguisorba, Portulaca and Rosmarinus. Pre-germination test was carried out in petri dishes, evidencing the need to overcome seed dormancy through cold stratification in Salicornia europaea. Thereafter, seeds were germinated in small trays with peat moss substrate in two growth chambers illuminated with either LED or fluorescent light featuring similar photosynthetic photon flux density. Germination lasted 20 days, during which time five indexes of germination performance (germination percentage, speed of germination, germination energy, germination rate index, and mean daily germination) were evaluated. At the end, shoot length and seedling fresh weight were assessed as early growth traits. Data are made available to allow critical evaluation of experimental outcome.