Structure, Functionality, Compatibility with Pesticides and Beneficial Microbes, and Potential Applications of a New Delivery System Based on Ink-Jet Technology.

Accurate application of agrochemicals is an important way to achieve efficient use of chemicals and to combine limited pollution with effective control of weeds, pests, and diseases. In this context, we investigate the potential application of a new delivery system based on ink-jet technology. First, we describe the structure and functionality of ink-jet technology for agrochemical delivery. We then evaluate the compatibility of ink-jet technology with a range of pesticides (four herbicides, eight fungicides, and eight insecticides) and beneficial microbes, including fungi and bacteria. Finally, we investigated the feasibility of using ink-jet technology in a microgreens production system. The ink-jet technology was compatible with herbicides, fungicides, insecticides, and beneficial microbes that remained functional after passing through the system. In addition, ink-jet technology demonstrated higher area performance compared to standard nozzles under laboratory conditions. Finally, the application of ink-jet technology to microgreens, which are characterized by small plants, was successful and opened the possibility of full automation of the pesticide application system. The ink-jet system proved to be compatible with the main classes of agrochemicals and showed significant potential for application in protected cropping systems.

Field evidence for litter and self-DNA inhibitory effects on Alnus glutinosa roots.

Litter decomposition releases nutrients beneficial to plants but also induces phytotoxicity. Phytotoxicity can result from either labile allelopathic compounds or species specific and caused by conspecific DNA. Aquatic plants in flowing water generally do not suffer phytotoxicity because litter is regularly removed. In stagnant water or in litter packs an impact on root functionality can occur. So far, studies on water plant roots have been carried out in laboratory and never in field conditions. The effect of conspecific vs heterospecific litter and purified DNA were assessed on aquatic roots of the riparian woody species Alnus glutinosa L. using a novel method, using closed and open plastic tubes fixed to single roots in the field with closed tubes analogous to stagnant water. Four fresh and four decomposed litter types were used and analysed on extractable C, cellulose, lignin, N content and using 13 C-CPMAS NMR spectroscopy. Inhibitory effects were observed with fresh litter in closed systems, with a positive correlation with extractable C and negative with lignin and lignin : N ratio. Alnus self-DNA, but not heterologous one, caused acute toxic effects in the closed system. Our results demonstrate the first field-based evidence for self-DNA inhibition as causal factor of negative feedback between plants and substrate.

Metabolomics and chemometrics of seven aromatic plants: Carob, eucalyptus, laurel, mint, myrtle, rosemary and strawberry tree.

INTRODUCTION: Arbutus unedo L. (strawberry tree), Ceratonia siliqua L. (carob), Eucalyptus camaldulensis Dehnh. (eucalyptus), Laurus nobilis L. (laurel), Mentha aquatica L. (water mint), Myrtus communis L. (common myrtle), and Rosmarinus officinalis L. (rosemary) are aromatic plants from the Mediterranean region whose parts and preparations are used for their nutritional properties and health benefits. OBJECTIVES: To evaluate and compare the metabolites profile, total phenol content (TPC), and antioxidant activity of plant leaves for their future use. Gas chromatography-mass spectrometry (GC-MS) was used for metabolomics. Data comparison was performed by chemometrics. METHODOLOGY: Polar and apolar extracts were analysed using untargeted GC-MS metabolomics followed by chemometrics (principal component analysis, heatmap correlation and dendrogram) to identify, quantify and compare the major organic compounds in the plants. Additionally, nuclear magnetic resonance (NMR) spectroscopy was used for the laurel polar extract to identify d-gluco-l-glycero-3-octulose whose presence was unclear from the GC-MS data. TPC and antioxidant assays were performed using classical methods (Folin-Ciocalteu, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH)) and correlated to the phytochemical profiles. RESULTS: Forty-three metabolites were identified including amino acids, organic acids, carbohydrates, phenols, polyols, fatty acids, and alkanes. Eight metabolites (d-fructose, d-glucose, d-mannose, gallic acid, quinic acid, myo-inositol, palmitic and stearic acids) were in common between all species. d-Gluco-l-glycero-3-octulose (37.29 ± 1.19%), d-pinitol (31.33 ± 5.12%), and arbutin (1.30 ± 0.44%,) were characteristic compounds of laurel, carob, and strawberry tree, respectively. Carob showed the highest values of TPC and antioxidant activity. CONCLUSION: GC-MS metabolomics and chemometrics analyses are fast and useful methods to determine and compare the metabolomics profiling of aromatic plants of food and industrial interest.

Contrasting effects of Rhizophagus irregularis versus bacterial and fungal seed endophytes on Trifolium repens plant-soil feedback.

Interactions between plants and soil affect plant-plant interactions and community composition by modifying soils conditions in plant-soil feedback, where associated microbes have the most crucial role. Both arbuscular mycorrhizal fungi (AMF) and microbial seed endophytes have been demonstrated to influence, directly or indirectly, biotic or abiotic soil properties, thus affecting subsequent plant growth, and community structure. However, little is known about how plant endophyte communities, individually or in interaction with AMF, affect plant-soil feedback processes. Here, we investigated, through a manipulative experiment, the behavior of endophyte-free and endophyte-associated Trifolium repens plants grown in soils previously conditioned by conspecific endophyte-free and endophyte-associated plants, inoculated or not by Rhizophagus intraradices. Furthermore, we identified microbial endophytes directly from the inner tissues of seeds by high-throughput sequencing, to compare seed fungal and bacterial endophyte composition. Results demonstrated that the outcome of simultaneous occurrence of seed endophytes and AMF on plant behavior depended on matching the endophytic status, i.e., either the presence or absence of seed microbial endophytes, of the conditioning and response phase. Seed fungal endophytes generated strong conspecific negative feedback, while seed bacterial endophytes proved to shift the feedback from negative to positive. Moreover, the simultaneous occurrence of both seed endophytes with AMF could either generate or expand negative plant-soil feedback effects. Our results show that seed and root symbionts can play a significant role on setting conspecific plant-soil feedback.

One ring to rule them all: an ecosystem engineer fungus fosters plant and microbial diversity in a Mediterranean grassland.

Species coexistence in grasslands is regulated by several environmental factors and interactions with the soil microbial community. Here, the development of the Basidiomycetes fungus Agaricus arvensis, forming fairy rings, in a species-rich Mediterranean grassland, is described. Effects of the mycelial front on plants, fungi and bacteria were assessed by vegetation survey and next generation sequencing approaches. Our results showed a fungal-dependent shift in the community structure operated by a wave-like spread of fairy rings that decreased plant, fungal and bacterial diversity, indicating a detrimental effect of fairy rings on most species. The fairy rings induced successional processes in plants that enhanced the replacement of a community dominated by perennial plants with short-living and fast-growing plant species. In parallel, fungal and bacterial communities showed evident differences in species composition with several taxa associated within distinct sampling zone across the fairy rings. Notably, bacteria belonging to the Burkholderia genus and fungi of the genus Trichoderma increased in response to the advancing mycelium of A. arvensis. The profound changes in community composition and the overall increase in taxa diversity at ecosystemic scale suggest that fairy ring-forming fungi may act as ecosystem engineer species in Mediterranean grasslands.

AgriLogger: A New Wireless Sensor for Monitoring Agrometeorological Data in Areas Lacking Communication Networks.

The use of wireless technologies in the field of agriculture, or so-called smart or precision agriculture, is considered as one of the main efforts applied nowadays to multiply the food production on earth. However, wireless sensor network (WSN) technology is still at its early development stage and its application in agriculture and food industry is still rare due to the lack of farmers' awareness and outreach about the matter. This paper presents a new agro-sensor named AgriLogger with an aim to collect, store for long periods and transmit agrometeorological data represented by temperature and relative humidity in remote areas hard to reach and not served by telecommunication networks. The sensor exhibits long battery life, in the order of 10 years, thanks to low consumption technologies and to hardware sleep/wake up approach. It can be remotely placed on preselected sites through a customized drone. This latter, equipped with a dedicated payload, can then return on the sites where sensors have been placed, and, while hovering, wakes up the single devices and uploads their collected data through local wireless network. Field tests have demonstrated that the sensor, after being placed manually in two different positions, inside and outside a vineyard canopy, is able to collect and store successfully agrometeorological data like temperature and relative humidity. Moreover, the use of a drone potentially allows the collection of data from remote areas and, therefore, is able to provide a periodical monitoring of agro-ecological conditions.

Metabolomics of the alimurgic plants Taraxacum officinale, Papaver rhoeas and Urtica dioica by combined NMR and GC-MS analysis.

INTRODUCTION: The phytoalimurgic plants, common dandelion (Taraxacum officinale), corn poppy (Papaver rhoeas) and stinging nettle (Urtica dioica) are a source of nutraceuticals. OBJECTIVES: To apply a combined metabolomic fingerprinting approach by nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS) to common dandelion, corn poppy and stinging nettles to obtain simultaneous identification and quantitation of the major classes of organic compounds. METHODOLOGY: The whole plants collected in the Cilento National Park were dried and then extracted to obtain non-polar and polar organic extracts. GC-MS was used for non-polar extracts while 1 H-NMR spectroscopy was used for polar extracts. In both cases, simultaneous identification and quantification of the bioactive metabolites was obtained. RESULTS: Non-polar organic extracts of all plants were mainly composed of palmitic, stearic and oleic acids. The two pentacyclic triterpenols α- and ß-amyrin were detected in nettle extract. The analysis of polar organic extracts allowed to detect and quantify organic acids and sugars as main metabolites along with amino acids, caffeoyl derivatives, flavonoids, and nucleotides. In particular, corn poppy leaves contained a huge amount of glyceric acid (55.7% of the total extract). Stinging nettles, instead, exhibited a large amount of choline (19.5%). CONCLUSION: Metabolomic approach coupling GC-MS with NMR spectroscopy allowed to provide a detailed metabolite profile of three alimurgic plants, common dandelion, corn poppy and stinging nettle, from both a qualitative and quantitative point of view.

Comparing chemistry and bioactivity of burned vs. decomposed plant litter: different pathways but same result?

Litter burning and biological decomposition are oxidative processes co-occurring in many terrestrial ecosystems, producing organic matter with different chemical properties and differently affecting plant growth and soil microbial activity. We tested the chemical convergence hypothesis, i.e., materials with different initial chemistry converge toward a common profile, with similar biological effects, as the oxidative process advances, for burning and decomposition. We compared the molecular composition, assessed by 13 C NMR, of seven plant litter types either fresh, decomposed for 30, 90, 180 d in a microcosms incubation experiment, or heated at 100°C, 200°C, 300°C, 400°C, 500°C for 30 minutes. We used litter water extracts (5% dry weight) as treatments in bioassays on plant (Lepidium sativum) and fungal (Aspergillus niger) growth, and a washed quartz sand amended with litter (0.5% dw) to assess heterotrophic respiration by flux chamber (i.e., [µg of CO2 released]·[g added litter]-1 ·d-1 ). We observed different molecular variations for materials either burning (i.e., a sharp increase of aromatic C and a decrease of other fractions above 200°C) or decomposing (i.e., early increase of alkyl, methoxyl, and N-alkyl C and decrease of O-alkyl and di-O-alkyl C fractions). Soil respiration and fungal growth decreased with litter age and heating severity, down to 20% relative to fresh litter. Plants were inhibited on fresh litter (on average 13% of the control), but recovered on aged (180 d) and heated (30 min at 500°C) materials, up to 126% and 63% of the control, respectively. Correlation between the intensity of 13 C NMR signals in litter spectra and bioassay results showed that O-alkyl, methoxyl, and aromatic C fractions are crucial to understand organic matter effects, with plant response negatively affected by labile C but positively associated to lignification and pyrogenic C. The pattern of association of soil respiration and fungal growth to these C fractions was essentially opposite to that observed for plant root growth. Our findings suggest a functional convergence of decomposed and burned organic substrates, emerging from the balance between the bioavailability of labile C sources and the presence of recalcitrant and pyrogenic compounds, oppositely affecting different trophic levels.

Essential Oil Composition, Antioxidant and Allelopathic Activities of Cleome droserifolia (Forssk.) Delile.

People rely on the synthetic chemical pesticides in most of the agricultural practices, which have a serious problem on human health and ecosystem. Essential oil (EO), derived from wild plants, offers a new opportunity to explore eco-friendly green biocides. This study aimed to characterize the chemical constituents of EO from Egyptian ecospecies of Cleome droserifolia (Forssk.) Delile and evaluate its antioxidant and allelopathic potential. The EO was extracted from aerial parts by hydrodistillation and analyzed by GC/MS. To assess the allelopathic potential, EO concentrations from 50 to 200 µL L-1 were tested on Trifolium repens and three weeds. Antioxidant activity was determined using DPPH. Hydrodistillation yielded 0.64 % of dark yellow oil, which comprises 35 compounds, in which sesquiterpene was a major class and represented by 61.97 % of the total essential oil. Moreover, the dominant sesquiterpenes are cis-nerolidol, α-cadinol, δ-cadinene, and γ-muurolene. The speed of germination index, shoot and root length of clover and weeds were reduced in a concentration-dependent manner. The IC50 values of C. droserifolia EO on germination of T. repens, Cuscuta trifolii, Melilotus indicus, and Chenopodium murale were 181.6, 183.5, 159.0, and 157.5 µL L-1 , respectively. From the obtained data, we concluded that C. droserifolia EO could provide a hope to produce environment-friendly bioherbicide as well as a natural resource of antioxidants.

Allelopathic Activity and Chemical Composition of Rhynchosia minima (L.) DC. Essential Oil from Egypt.

Aromatic plants attract the attention of many researchers worldwide due to their worthy applications in agriculture, human prosperity, and the environment. Essential oil (EO) could be exploited as effective alternatives to synthetic compounds as it has several biological activities including allelopathy. The EO from the aerial parts of Rhynchosia minima was extracted by hydrodistillation and investigated by gas chromatography/mass spectrometry (GC/MS). Different concentrations (50, 100, 150 and 200 µL L-1 ) of the EO were prepared for investigation of their allelopathic potential on two weeds; Dactyloctenium aegyptium and Rumex dentatus. Twenty-eight compounds, mainly sesquiterpenes (69.13%) were determined. The major compounds are α-eudesmol, 2-allyl-5-tert-butylhydroquinone, caryophyllene oxide, trans-caryophyllene, and τ-cadinol. The EO from the R. minima showed a significant inhibition of D. aegyptium and R. dentatus germination, while the seedling growth was stimulated. Therefore, it is not recommended to treat these noxious weeds with the EO of R. minima before the germination. In contrast, the apparent stimulatory effect on the seedling growth offers further studies to use the EO of R. minima to enhance the fitness of different economic crops. However, characterization of green bio-herbicides such as EO (allelochemicals) from wild plants raises a new opportunity for the incorporation of new technology of bio-control against the noxious weeds.

Inhibitory and toxic effects of extracellular self-DNA in litter: a mechanism for negative plant-soil feedbacks?

Plant-soil negative feedback (NF) is recognized as an important factor affecting plant communities. The objectives of this work were to assess the effects of litter phytotoxicity and autotoxicity on root proliferation, and to test the hypothesis that DNA is a driver of litter autotoxicity and plant-soil NF. The inhibitory effect of decomposed litter was studied in different bioassays. Litter biochemical changes were evaluated with nuclear magnetic resonance (NMR) spectroscopy. DNA accumulation in litter and soil was measured and DNA toxicity was assessed in laboratory experiments. Undecomposed litter caused nonspecific inhibition of root growth, while autotoxicity was produced by aged litter. The addition of activated carbon (AC) removed phytotoxicity, but was ineffective against autotoxicity. Phytotoxicity was related to known labile allelopathic compounds. Restricted (13) C NMR signals related to nucleic acids were the only ones negatively correlated with root growth on conspecific substrates. DNA accumulation was observed in both litter decomposition and soil history experiments. Extracted total DNA showed evident species-specific toxicity. Results indicate a general occurrence of litter autotoxicity related to the exposure to fragmented self-DNA. The evidence also suggests the involvement of accumulated extracellular DNA in plant-soil NF. Further studies are needed to further investigate this unexpected function of extracellular DNA at the ecosystem level and related cellular and molecular mechanisms.

Inhibitory effects of extracellular self-DNA: a general biological process?

Self-inhibition of growth has been observed in different organisms, but an underlying common mechanism has not been proposed so far. Recently, extracellular DNA (exDNA) has been reported as species-specific growth inhibitor in plants and proposed as an explanation of negative plant-soil feedback. In this work the effect of exDNA was tested on different species to assess the occurrence of such inhibition in organisms other than plants. Bioassays were performed on six species of different taxonomic groups, including bacteria, fungi, algae, plants, protozoa and insects. Treatments consisted in the addition to the growth substrate of conspecific and heterologous DNA at different concentration levels. Results showed that treatments with conspecific DNA always produced a concentration dependent growth inhibition, which instead was not observed in the case of heterologous DNA. Reported evidence suggests the generality of the observed phenomenon which opens new perspectives in the context of self-inhibition processes. Moreover, the existence of a general species-specific biological effect of exDNA raises interesting questions on its possible involvement in self-recognition mechanisms. Further investigation at molecular level will be required to unravel the specific functioning of the observed inhibitory effects.

Vegetation pattern formation due to interactions between water availability and toxicity in plant-soil feedback.

Development of a comprehensive theory of the formation of vegetation patterns is still in progress. A prevailing view is to treat water availability as the main causal factor for the emergence of vegetation patterns. While successful in capturing the occurrence of multiple vegetation patterns in arid and semiarid regions, this hypothesis fails to explain the presence of vegetation patterns in humid environments. We explore the rich structure of a toxicity-mediated model of the vegetation pattern formation. This model consists of three PDEs accounting for a dynamic balance between biomass, water, and toxic compounds. Different (ecologically feasible) regions of the model's parameter space give rise to stable spatial vegetation patterns in Turing and non-Turing regimes. Strong negative feedback gives rise to dynamic spatial patterns that continuously move in space while retaining their stable topology.

Long-Term Application of Biochar Mitigates Negative Plant-Soil Feedback by Shaping Arbuscular Mycorrhizal Fungi and Fungal Pathogens.

Negative plant-soil feedback (PSF) arises when localized accumulations of pathogens reduce the growth of conspecifics, whereas positive PSF can occur due to the emergence of mutualists. Biochar, a carbon-rich material produced by the pyrolysis of organic matter, has been shown to modulate soil microbial communities by altering their abundance, diversity, and activity. For this reason, to assess the long-term impact of biochar on soil microbiome dynamics and subsequent plant performance, we conducted a PSF greenhouse experiment using field soil conditioned over 10 years with Vitis vinifera (L.), without (e.g., C) or with biochar at two rates (e.g., B and BB). Subsequently, the conditioned soil was employed in a response phase involving either the same plant species or different species, i.e., Medicago sativa (L.), Lolium perenne (L.), and Solanum lycopersicum (L.). We utilized next-generation sequencing to assess the abundance and diversity of fungal pathogens and arbuscular mycorrhizal fungi (AMF) within each conditioned soil. Our findings demonstrate that biochar application exerted a stimulatory effect on the growth of both conspecifics and heterospecifics. In addition, our results show that untreated soils had a higher abundance of grape-specialized fungal pathogens, mainly Ilyonectria liriodendra, with a relative abundance of 20.6% compared to 2.1% and 5.1% in B and BB, respectively. Cryptovalsa ampelina also demonstrated higher prevalence in untreated soils, accounting for 4.3% compared to 0.4% in B and 0.1% in BB. Additionally, Phaeoacremonium iranianum was exclusively present in untreated soils, comprising 12.2% of the pathogens' population. Conversely, the application of biochar reduced generalist fungal pathogens. For instance, Plenodomus biglobosus decreased from 10.5% in C to 7.1% in B and 2.3% in BB, while Ilyonectria mors-panacis declined from 5.8% in C to 0.5% in B and 0.2% in BB. Furthermore, biochar application was found to enrich the AMF community. Notably, certain species like Funneliformis geosporum exhibited increased relative abundance in biochar-treated soils, reaching 46.8% in B and 70.3% in BB, compared to 40.5% in untreated soils. Concurrently, other AMF species, namely Rhizophagus irregularis, Rhizophagus diaphanus, and Claroideoglomus drummondii, were exclusively observed in soils where biochar was applied. We propose that the alleviation of negative PSF can be attributed to the positive influence of AMF in the absence of strong inhibition by pathogens. In conclusion, our study underscores the potential of biochar application as a strategic agricultural practice for promoting sustainable soil management over the long term.

Negative plant-soil feedback in Arabidopsis thaliana: Disentangling the effects of soil chemistry, microbiome, and extracellular self-DNA.

Nutrient deficiency, natural enemies and litter autotoxicity have been proposed as possible mechanisms to explain species-specific negative plant-soil feedback (PSF). Another potential contributor to negative PSF is the plant released extracellular self-DNA during litter decay. In this study, we sought to comprehensively investigate these hypotheses by using Arabidopsis thaliana (L.) Heynh as a model plant in a feedback experiment. The experiment comprised a conditioning phase and a response phase in which the conditioned soils underwent four treatments: (i) addition of activated carbon, (ii) washing with tap water, (iii) sterilization by autoclaving, and (iv) control without any treatment. We evaluated soil chemical properties, microbiota by shotgun sequencing and the amount of A. thaliana extracellular DNA in the differently treated soils. Our results showed that washing and sterilization treatments mitigated the negative PSF effect. While shifts in soil chemical properties were not pronounced, significant changes in soil microbiota were observed, especially after sterilization. Notably, plant biomass was inversely associated with the content of plant self-DNA in the soil. Our results suggest that the negative PSF observed in the conditioned soil was associated to increased amounts of soilborne pathogens and plant self-DNA. However, fungal pathogens were not limited to negative conditions, butalso found in soils enhancing A.thaliana growth. In-depth multivariate analysis highlights that the hypothesis of negative PSF driven solely by pathogens lacks consistency. Instead, we propose a multifactorial explanation for the negative PSF buildup, in which the accumulation of self-DNA weakens the plant's root system, making it more susceptible to pathogens.

Temperature sensitivity and decomposition rate of 101 leaf litter types from Mediterranean ecosystems.

Litter decomposition is a fundamental process, and the number of published studies has steadily increased in recent decades. However, few experiments have systematically compared a large number of litter types and evaluated their temperature sensitivity. We conducted a two-year experiment on the decomposition of litter bags containing 101 leaf litter sampled in Mediterranean ecosystems and incubated under laboratory conditions at 4 °C, 14 °C, and 24 °C. Litter was chemically characterized and analysed for carbon (C), nitrogen (N), cellulose and lignin concentration, C/N, and lignin/N ratios, which serve as predictors of decomposition rate. The sensitivity of litter decay rate to temperature was evaluated using Q10. Leaf litter chemistry varied widely in nitrogen content (range 0.52-6.80 %), lignin content (range 1.53-49.31 %), C/N ratio (range 5.21-77.78), and lignin/N ratio (range 0.34-34.90). Litter decomposition rate was negatively related to initial lignin concentration, lignin/N ratio, and C/N ratio, but only in the early stage. In the late stages of decomposition, litter decay rate was negatively correlated with initial N concentration but positively correlated with C/N and lignin/N ratios. Temperature sensitivity was negatively correlated with N concentration and positively correlated with lignin and lignin/N ratio. It is noteworthy that, contrary to expectations, temperature sensitivity exhibited a hump-shaped relationship with decay rate. N, C/N, and lignin/N ratios should be used with caution because their predictive power is reversed with respect to decomposition rate during the decomposition process. In addition, the new finding that temperature sensitivity has a hump-shaped relationship with decomposition rate deserves further confirmation and could be considered in ecosystem-level organic C modeling.

Adult conspecific density affects Janzen-Connell patterns by modulating the recruitment exclusion zones.

Plant-soil negative feedback (NF) is a well-established phenomenon that, by preventing the dominance of a single species, allows species coexistence and promotes the maintenance of biodiversity. At community scale, localized NF may cause the formation of exclusion zones under adult conspecifics leading to Janzen-Connell (JC) distribution. In this study, we explore the connection between adult density, either conspecifics or heterospecifics, on the probability of occurrence of JC distributions. Using an individual-based modelling approach, we simulated the formation of exclusion zones due to the build-up of NF in proximity of conspecific adult plants and assessed the frequency of JC distribution in relation to conspecifics and heterospecifics density ranging from isolated trees to closed forest stands. We found that JC recruitment distribution is very common in the case of an isolated tree when NF was strong and capable to form an exclusion zone under the parent tree. At very low NF intensity, a prevalence of the decreasing pattern was observed because, under such conditions, the inhibitory effect due to the presence of the mother tree was unable to overcome the clustering effect of the seed dispersal kernel. However, if NF is strong the JC frequency suddenly decreases in stands with a continuous conspecific cover likely as a result of progressive expansion of the exclusion zone surrounding all trees in closed forest stands. Finally, our simulations showed that JC distribution should not be frequent in the case of rare species immersed in a matrix of heterospecific adults. Overall, the model shows that a plant suffering from strong NF in monospecific stands can rarely exhibit a recruitment pattern fitting the JC model. Such counterintuitive results would provide the means to reconcile the well-established NF framework with part the forest ecologists' community that is still skeptical towards the JC model. Synthesis: Our model highlights the complex interconnection between NF intensity, stand density, and recruitment patterns explaining where and why the JC distribution occurs. Moreover, predicting the occurrence of JC in relation to stand density we clarify the relevance of this ecological phenomenon for future integration in plant community frameworks.

Ethnobotanical Documentation of the Uses of Wild and Cultivated Plants in the Ansanto Valley (Avellino Province, Southern Italy).

With approximately 2800 species, the Campania region has the richest vascular flora in southern Italy and the highest number of medicinal species reported in the Italian folk traditions. The study area is inserted in a wide rural landscape, still retaining a high degree of naturalness and is studied for the first time from an ethnobotanical point of view. By analyzing local traditional uses of wild plants in the Ansanto Valley area, the present study aims to contribute to the implementation of ethnobotanical knowledge concerning southern Italy. To gather ethnobotanical knowledge related to the Ansanto Valley, 69 semi-structured interviews were carried out through a snowball sampling approach, starting from locals with experience in traditional plant uses (key informants). A number of 117 plant species (96 genera and 46 families) were documented for traditional use from a total of 928 reports, of which 544 were about medicinal plants. New use reports on the utilization of plants for medicinal (5) and veterinary applications (8) in the Campania region and the whole Italian territory were outlined from our investigations. Sedum cepaea is reported as a medicinal plant for the first time in Italy and in the whole Mediterranean basin.

Shifts of Leaf Litter-Induced Plant-Soil Feedback from Negative to Positive Driven by Ectomycorrhizal Symbiosis between Quercus ilex and Pisolithus arrhizus.

Ectomycorrhizas (ECM) are a common symbiotic association between fungi and various plant species in forest ecosystems, affecting community assemblages at the landscape level. ECMs benefit host plants by increasing the surface area for nutrient uptake, defending against pathogens, and decomposing organic matter in the soil. ECM-symbiotic seedlings are also known to perform better in conspecific soils than other species unable to carry the symbiosis, in a process referred to as plant-soil feedback (PSF). In this study, we tested the effects of different leaf litter amendments on ECM and non-ECM seedlings of Quercus ilex inoculated with Pisolithus arrhizus and how they altered the litter-induced PSF. Our experiment showed that the ECM symbiont induced a shift from negative PSF to positive PSF in Q. ilex seedlings by analysing plant and root growth parameters. However, non-ECM seedlings performed better than ECM seedlings in a no-litter condition, indicating an autotoxic effect when litter is present without ECM symbionts. Conversely, ECM seedlings with litter performed better at different decomposition stages, suggesting a possible role of the symbiosis of P. arrhizus and Q. ilex in recycling autotoxic compounds released from conspecific litter, transforming them into nutrients that are transferred to the plant host.