1,721,011 research outputs found
Chitosan nanoparticles for sustainable agriculture: interactions with leaf surface and protective effect on dsRNA as functionalizing agent
Full text linkClimate change and population growth are causing significant issues in the agricultural world, among which the worsening of environmental stresses suffered by crops and the inefficient use of resources must be highlighted. That’s why it’s necessary to find eco-sustainable solutions that can guarantee adequate production efficiency without affecting environmental health. Among the most advanced technologies, the development of nanomaterials partially replacing the conventional treatments with synthetic pesticides and fertilizers, stands out, given their more efficient transport of bioactive substances to plants and protection from damaging factors. Considering organic materials, nano-chitosan is even eco-compatible and obtainable through circular economy.
Another innovation concerning the defense of crops is the exploitation of the so-called RNA-interference mechanism. Specific dsRNAs targeting an essential gene of a pathogen or weed can be applied exogenously, triggering a pathway that leads to gene silencing into the organism. A major issue, however, consists in the easy degradability of these sequences if applied naked, which makes the technology still unlikely for agricultural up-scaling.
In this regard, the aim of our research was to verify the feasibility of dsRNA application on plants by means of functionalized chitosan nanoparticles (NPs), thus allowing its efficient delivery and protection. After defining the best synthesis protocol of NPs, these were used for different tests. To verify their ability to adhere to the leaf surface, they were observed by confocal microscope on two plant species thanks to a fluorescent probe. Subsequently, after their functionalization with nucleotides, their protective capacity was studied. These tests proved to be fundamental for the prosecution of the work concerning the evaluation of the formulation efficacy on plant pathogens
Success of native hay-seed mix for dry grassland restoration: do not neglect the role of soil seed bank
No full textEcological restoration has been proved to be an effective strategy to contrast biodiversity loss due to land use change. Among terrestrial ecosystems, dry grasslands represent biodiversity hotspot strongly threatened by soil consumption. Passive grassland restoration, based on spontaneous succession, is highly unpredictable and, in some cases, unsuitable to re-establish native communities. The use of spontaneous seeds (hay seed) and or/ commercial seed mix might contribute to boost early restoration stages by triggering native plant colonization. A crucial stage for the success of any restoration action and for determining community composition is the seeds germination. In addition, the soil seedbank of restoration sites can exert main effect on the final plant assembly, even if
it is often neglected. We designed a controlled environment experiment in which commercial grassland seed-mix and spontaneous hay seeds collected in local dry grassland were sown on commercial soil (seedbank less) and agricultural soil (with seedbank) with two seed density. We hypothesized soil, seed mix type and density to interplay in determining community diversity and composition. Commercial seed provided greater species abundance and rapid containment of seedbank species. The abundance of the seedbank ruderal species greatly contributed to the total biodiversity in the case of hay seeds. The number of individuals of species not belonging to the seedbank has always been higher if commercial seed mix was sown; in the case of hay seeds this parameter was favored by agricultural soil probably due to the substrate or to positive interaction with seedbank species. The composition of functional groups (i.e. monocot vs dicot and life span) and species assembly were also influenced by the soil and seed mix type. Soil seedbank effect in determining the success of site restoration when operating seed sowing
should not be overlooked, alternative management actions aimed at curb seedbank germination should be, hence, considered
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
From wood anatomy to satellites: new frontiers for the upscaling of climate change in the Alpine tundra
Full text linkTree ring growth is strictly bound to annual environmental conditions. Therefore, dendrochronology represents a solid tool for investigating the relationship between the whole plant growth and climate at high temporal resolution, especially in the context of ongoing climate change.
The temperature increase in the Alpine and Arctic ecosystems has been proven to enhance shrub growth contributing to the Arctic/Alpine greening, while the effects of the interaction between temperature and other climatic variables (e.g. precipitation/snowfall regime) on the shrub growth have often been neglected. With the aim of parsing the relationships between the annual growth of Vaccinium myrtillus L., a key species in the Alpine tundra, temperature, precipitation, snowfall regime (i.e., in terms of
temperature-based snowfall, known as snow water equivalent) and their interaction, we analyzed the xylem rings of 100 cross sections of underground bilberry stem, collected along a 500 meters altitude gradient above the tree line and corresponding over a period of 20 years (1995-2015). Furthermore, aiming at linking different ecological scales, we have adopted an ecological upscaling approach. With reference to the area and the period considered, we calculated NDVI using satellite images, and we studied the relationships between this vegetation index, climate, and the anatomical parameters.
Our results showed that both number (i.e. ramet age) and mean width of the rings were negatively affected by altitude. The mean annual temperature and snowfall showed significant interaction effects on mean ring width and xylem mean lumen area. Cold years (i.e. low mean annual temperature) and abundant snowfall led to a reduction in the mean ring width, while the snowfall regime did not affect annual ring width in warm years. Xylem mean lumen area was affected by precipitation only in cold years. The mean growth season NDVI increased significantly in the time span considered and showed a positive relationship with the average age of the bilberry community. The interaction between rainfall and average temperature of the vegetative season influenced the NDVI: a negative relationship between vegetation index and rainfall was observed in cooler vegetative seasons, while the relationship was specular in the case of highertemperatures. These results suggest that future scenarios should not overlook the precipitation regime effect by virtue of its possible role in snowpack permanence and drought during the growth season. In this light the shrub expansion could also be curbed by the change of precipitation regime and the
increased frequency of extreme climate events (e.g., shift of snowfall regime and intensification of heat waves). Moreover, our findings confirmed the potential use of the remote sensing tool for the understanding of the response of dwarf shrub communities to climate change also for long-term monitoring of these plant communities
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The shape of plant community to come: linking species functional response and climate-induced shifts in alpine tundra dwarf shrub community
No full textShrub expansion is a prominent effect of climate warming in both arctic and alpine regions, which is leading to a vast arctic and alpine greening (Myers-Smith et al., 2020). For this reason, understanding the response of dwarf shrubs to main climate drivers is of outmost importance. Climate changes induce plants to acclimate by both morphological and physiological traits due their phenotypic plasticity. A functional trait approach is hence crucial to foresee the response of key species of the ecosystems, which changes could also affect the entire community (Boscutti et al., 2018). Moreover, species with similar functional traits are assumed to respond to environmental modifications in comparable ways. Hence, the response of key species sharing similar traits might reverberate on the entire ecosystem proprieties, promoting an effective upscaling perspective (Fig. 1). Temperature is a well-known driver of shrub expansion, while its interplay with other climate variables (e.g. rainfall regime) has
been often overlooked. This study aims at parsing the relationships between the climateinduced functional response of the key species Vaccinium myrtillus L. and the entire plant community. We here present the results of an observational study along an elevation gradient and a rain exclusion experiment conducted in alpine tundra in the north-eastern Alps. In the observational study, we found alpine greening of dwarf shrub community to be associated to temperature, but only when precipitation sustained the V. myrtillus growth (i.e. high temperature and high precipitations). In the rain manipulative experiment, instead, we found precipitation to induce a trait-mediated plant community response, favouring graminoid species in contrast to forbs, especially in stands where shrub expansion was not completed (half cover of dwarf shrubs), suggesting that species acclimation to drought relies not only on species response, but also on the whole community traits. This might argue that the ongoing increase of summer heat wave frequency in the alpine range could partially contrast the shrub expansion and, in turn, favor alpine grassland species, more adapted to water scarcity. These results might reverberate on the whole plant community, affecting the overall diversity, by changes in species richness and species composition. We suggest that future scenarios depicting the fate of alpine plant community should not neglect for the interplay of temperature and precipitation regimes and that a plant trait approach would be crucial in the understanding of ecological mechanisms underlying the change of plant community, especially in high elevation ecosystems
Alien plant invasion during early succession stages of dune systems is driven by soil properties
No full textBiological invasion is nowadays recognised as one of the major threats to biodiversity (1). This is particularly true for coastal habitats, where dunes are considered one of the most invaded habitat worldwide. Many studies linked the success of alien plant invasion in dune ecosystems to human disturbances, but less is known about the role of soil properties in plant invasion. Soil properties can directly affect plant dune colonization and the final community composition (2,3). This is expected to be linked to the interplay of soil and the plant functional response, generating important plant-soil feedbacks able to reverberate on the community structure and composition. Plant-soil interactions are thus expected to be crucial in explaining the invasion processes, but their role in dune alien colonization in mostly unknown.
We performed a manipulative experiment in a barrier island of the Marano and Grado’s lagoon, Northern Adriatic Sea. The whole plant community of backdune was erased by a soil miller in the selected plots to trigger a new ecological succession and test the mechanism of alien plant invasion during the early stages of plant colonization. In 8 experimental bocks, we altered soil properties by adding salt, nitrogen and organic matter (i.e. peat) and combining those treatments in 1 m2 plots with a factorial design (i.e. 8 replicates × 8 treatments = 64 plots). We recorded the emergence of seedlings with a camera system every 15 days. At the end of experiments, we recorded the plant community composition and measured the following traits: plant height, species cover, number of individuals, leaf pigments, SLA. Moreover, those traits were calculated for the overall community and for the key species (Cakile maritima Scop.) We also estimated the decomposition rate of the soil using the Tea Bag Index. In addition, the same parameters were collected in 8 reference plots (i.e. surrounding unaltered plant community).
The results showed that most of the treatments decreased the species richness of alien plants, in particular where soil salt content was enhanced. Moreover, some treatments had positive effects on the native plant cover and decreased the overall number of alien individuals, potentially reducing the initial propagule pressure due to the soil seed bank and, hence, changing the further plant community trajectories. This study provides new information on conservation and management efforts in this ecologically sensitive area, giving new insight into the dynamics of biological invasion and the impacts on native ecosystems
Remote sensing tools to parse the acclimation response of saltmarshes to flooding stress: upscaling perspectives in lagoon systems
No full textSea level rise is considered a prominent aftermath of the ongoing global warming, which is expected to seriously treat the worldwide coasts. Among coastal environments, saltmarshes harbor plant communities particularly sensitive to the increase of flooding. Although saltmarshes might contrast sea level rise by accretion and niche shifting, sea rise rates and the coastal squeeze phenomenon undermine the acclimation capacity of such plant communities. For these reasons, parsing the underlying mechanisms of the response of saltmarshes to flooding is of outmost importance to foresee the future scenarios for these important ecosystems. In this light, linking different ecological scales using an upscaling approach might provide new insight into the ecological processes involved. We analyzed main traits of plant community and the growth of the key species Salicornia fruticosa (L.) L. in 9 saltmarshes along the flooding gradient (Marano and Grado lagoon, northern Adriatic Sea). In particular, we considered community (i.e. species richness, dry biomass, dry matter content) and individual growth (i.e. shoot annual growth, dry biomass, dry matter content, plant height) and physiological traits (i.e. pigments and secondary metabolite content) in response to flooding gradient. Concurrently we carried out a UAV (Unnamed Aerial Vehicle) multispectral survey, in order to obtain remote sensing-derived vegetation indices (i.e. NDVI - Normalized Difference Vegetation Index, LCI - Leaf Chlorophyll Index, ARI - Anthocyanin Reflectance Index) for the upscaling of plant responses. We found that the flooding gradient produced a significant decrease of plant biomass and growth, affecting both plant traits and plant community features. We also found remote sensing-derived indices to be related to the analyzed plant traits, showing promising perspectives for the upscaling plant flooding stress response. In particular, NDVI was mainly linked to individual annual plant shoot elongation while the other indices were also related to stem pigments and secondary metabolites content. Our findings shed new light on the potential use of the remote sensing tool for the understanding of the response of saltmarshes vegetation to the future increase of the sea level, proving to be a promising method for long-term monitoring of these plant communities
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