Arable plant communities as a surrogate of crop rhizosphere microbiota.

Soil microbiota is a crucial component of agroecosystem biodiversity, enhancing plant growth and providing important services in agriculture. However, its characterization is demanding and relatively expensive. In this study, we evaluated whether arable plant communities can be used as a surrogate of bacterial and fungal communities of the rhizosphere of Elephant Garlic (Allium ampeloprasum L.), a traditional crop plant of central Italy. We sampled plant, bacterial, and fungal communities, i.e., the groups of such organisms co-existing in space and time, in 24 plots located in eight fields and four farms. At the plot level, no correlations in species richness emerged, while the composition of plant communities was correlated with that of both bacterial and fungal communities. As regards plants and bacteria, such correlation was mainly driven by similar responses to geographic and environmental factors, while fungal communities seemed to be correlated in species composition with both plants and bacteria due to biotic interactions. All the correlations in species composition were unaffected by the number of fertilizer and herbicide applications, i.e., agricultural intensity. Besides correlations, we detected a predictive relationship of plant community composition towards fungal community composition. Our results highlight the potential of arable plant communities to be used as a surrogate of crop rhizosphere microbial communities in agroecosystems.

Uptake of Trace Elements in the Water Fern Azolla filiculoides after Short-Term Application of Chestnut Wood Distillate (Pyroligneous Acid).

Treatments of crops with additives to increase their productivity may pose environmental risks and induce negative effects also on non-target organisms. In this study, we investigated the potential effect of chestnut wood distillate (pyroligneous acid) used in agriculture, on the accumulation of trace elements in aquatic plants. As a model species, the common water fern Azolla filiculoides Lam. was selected, being often used also in phytoremediation processes. The content of selected elements of toxicological concern (As, Ba, Cd, Cu, Fe, Mn, Ni, Pb, Zn) was assessed in the fern after short-term treatments (1-3 days) over a range of wood distillate concentrations 1:300 (3.33 mL/L), 1:500 (2.00 mL/L), 1:700 (1.43 mL/L). A statistically significant accumulation of Cd, Cu, Mn, Pb, Zn (1:700) and Pb (1:300) was recorded after three days of incubation, despite the concentrations remained overall low. Using treatment vs. control ratios, a trend of increasing temporal uptake was detected for As, Ba, Fe, Mn, Pb (1:700); Mn, Pb (1:500), and only Pb at 1:300. The results suggested that, under the experimental conditions, element uptake is positively influenced by time and negatively by increasing concentrations of wood distillate, likely due to the acidification of the medium. On the whole, the element concentrations measured in A. filiculoides were low and did not pose any toxicological concern.

Effects of wood distillate (pyroligneous acid) on sensitive bioindicators (lichen and moss).

Wood distillate (pyroligneous acid) can be successfully applied in agriculture to increase crop quality and productivity with a lower risk for the environment respect to synthetic chemical herbicides, pesticides or fertilizers. However, the effects of wood distillate on the environment and biota are still under investigation, depending on biological attributes of potentially influenced organisms. The potential toxicological effects of wood distillate on sensitive non-target organisms, lichens and mosses, are studied for the first time. The physiological parameters (chlorophyll a fluorescence emission FV/FM and PI(ABS), chlorophyll content, spectral reflectance, antioxidant power, and dehydrogenase activity) and eventual bioaccumulation of selected elements (As, Ba, Cd, Cr, Cu, Fe, Ni, Pb, Zn) were investigated in the lichen Xanthoria parietina and the moss Hypnum cupressiforme after short-term treatments over a range of wood distillate solutions (1:300, 1:500, 1:700) to detect potential early stress responses. Overall, the lichen did not show changes after the treatments, while in the moss wood distillate caused only modest alterations in FV/FM and PI(ABS) and progressive increasing of antioxidant activity according to the dose supplied. The bioaccumulation of toxic elements was low and did not show any pattern of uptake with increasing concentrations of wood distillate.