Leaf Washing Research Articles

Artificial nanovesicles for dsRNA delivery in spray-induced gene silencing for crop protection.

Spray-induced gene silencing (SIGS) is an innovative and eco-friendly technology where topical application of pathogen gene-targeting RNAs to plant material can enable disease control. SIGS applications remain limited because of the instability of RNA, which can be rapidly degraded when exposed to various environmental conditions. Inspired by the natural mechanism of cross-kingdom RNAi through extracellular vesicle trafficking, we describe herein the use of artificial nanovesicles (AVs) for RNAencapsulation and control against the fungal pathogen, Botrytis cinerea. AVs were synthesized using three different cationic lipid formulations, DOTAP + PEG, DOTAP and DODMA, and examined for their ability to protect and deliver double stranded RNA (dsRNA). All three formulations enabled dsRNA delivery and uptake by B. cinerea. Further, encapsulating dsRNA in AVs provided strong protection from nuclease degradation and from removal by leaf washing. This improved stability led to prolonged RNAi-mediated protection against B. cinerea both on pre- and post-harvest plant material using AVs. Specifically, the AVs extended the protection duration conferred by dsRNA to 10 days on tomato and grape fruits and to 21 days on grape leaves. The results of this work demonstrate how AVs can be used as a new nanocarrier to overcome RNA instability in SIGS for crop protection.

Natural variation and drought-induced differences in metabolite profiles of red oak-leaf and Romaine lettuce play a role in modulating the interaction with Salmonella enterica

Nutrients on produce surfaces are vital for successful enteric pathogen colonisation. In this study, we investigated natural variation in metabolite profiles of Romaine ‘Parris Island Cos’ and red oak-leaf lettuce ‘Mascara’ under regular and restricted watering conditions. We also investigated the impact of plant drought stress on the Salmonella – lettuce association. Salmonella Newport and Typhimurium were able to persist at higher levels on regularly watered Romaine than red oak-leaf lettuce. Drought treatment to lettuce impaired epiphytic Salmonella association, with S. Newport and Typhimurium being differentially affected. A higher log reduction of both serotypes was measured on drought-subjected red oak-leaf lettuce plants than controls, but S. Typhimurium was unaffected on water deficit-treated Romaine lettuce (p < 0.05). To assess Salmonella interaction with leaf surface metabolites, leaf washes collected from both cultivars were inoculated and found to be able to support S. Newport growth, with higher levels of Salmonella retrieved from Romaine washes (p < 0.05). The lag phase of S. Newport in washes from water restricted red oak-leaf lettuce was prolonged in relation to regularly-watered controls (p < 0.05). Untargeted plant metabolite profiling using electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) revealed natural variation between Romaine and red oak-leaf lettuce profiles for leaf tissue and leaf washes. Metabolite profile shifts were detected in both lettuce types in response to drought stress, but more unique peaks were detected in red oak-leaf than Romaine lettuce after drought treatment. Variation between the two cultivars was in part attributed to naturally higher levels of flavonoids and anthocyanins in red oak-leaf lettuce compared to Romaine. Moreover, red oak-leaf, but not Romaine lettuce, responded to drought by inducing the accumulation of proline, phenolics, flavonoids and anthocyanins. Drought stress, therefore, enhanced the functional food properties of red oak-leaf lettuce. Salmonella growth dynamics in lettuce leaf washes suggested that natural variation and drought-induced changes in metabolite profiles in lettuce could partly explain the differential susceptibility of various lettuce types to Salmonella, although the primary or secondary metabolites mediating this effect remain unknown. Regulated mild water stress should be investigated as an approach to lower Salmonella contamination risk in suitable lettuce cultivars, while simultaneously boosting the health beneficial quality of lettuce.

Developmentally related and drought-induced shifts in the kale metabolome limited Salmonella enterica association, providing novel insights to enhance food safety

Plants influence epiphytic bacterial associations but Salmonella enterica colonizes crop plants commensally, raising the possibility of human foodborne illness, but the factors that mediate human pathogen-plant associations remain understudied. We evaluated whether any changes in leaf tissue and surface metabolomes with kale (Brassica oleracea Acephala group) development and in response to drought modulated Salmonella leaf association. Untargeted phytochemical profiling (including primary and secondary metabolites) of kale leaf tissue extracts and leaf surface washes revealed distinct metabolite profiles that shifted with plant development. Metabolomes of juvenile plants also diverged in response to drought stress, an effect not noted in mature kale. Restricted watering in juvenile plants led to up-accumulation of 45 compounds in leaf tissue and 21 in leaf wash and the appearance of several unique peaks, with concomitant increases in phytochemical measurements. The antioxidant capacity and total flavonoid content were higher in mature than juvenile, regularly watered plant leaf extracts. Drought also elicited flavonoids and glucosinolates in juvenile plants. In mature plants, drought did not induce further prominent changes. Regularly watered juvenile kale provided a favorable substrate for inoculated Salmonella but the ability to support Salmonella declined with age and with drought stress. Salmonella growth was impaired in mature or water-stressed plant washes compared to controls and positive correlations were detected between Salmonella counts on leaves and in leaf washes. Moreover, Salmonella counts were inversely correlated with total flavonoids and phenolics in kale tissues from juvenile plants and regularly watered plants. Future studies should assess how changes in primary and secondary metabolites on the kale plant surface can modulate the Salmonella association. Regulated water restriction could be a strategy in controlled agriculture, with the dual purpose of enhancing health beneficial quality and food safety, especially when harvested at the baby kale stage.

Evaluation of Different Phyllosphere Sample Types for Parallel Metabarcoding of Fungi and Oomycetes in Vitis vinifera

Metabarcoding is an effective and cost-efficient approach to study environmental microbiomes and has become a standard method in studying microbial community structures and relative species abundance. In grapevine research on leaf microbial communities, two kinds of sample types, either leaf wash sediments representing the phyllosphere microbiome from leaf surfaces or leaf tissue samples, e.g., leaf disks, including phyllosphere and endosphere microorganisms, are used to characterize leaf microbiomes. The goal of this study was to analyze the advantages and disadvantages of these sample preparation methods for the characterization of the phyllosphere microbiome by fungal metabarcoding with both sample types being processed from the exact same set of leaves. We used a metabarcoding strategy, which can detect Fungi and Oomycetes, facilitating the parallel analysis of these communities. At each sampling time point, species richness was shown to be higher in leaf wash samples, and differences in the community structure between samples was smaller for this sample type as well. Furthermore, by comparing read count abundance to qPCR measured relative proportions of selected amplicon sequence variants, a higher congruence was observed for leaf wash samples. Therefore, metabarcoding analyses of leaf samples using leaf wash sediments outperform analyses using leaf disks and should be applied to characterize phyllosphere fungal communities. As a second goal, we show that the direct comparison of metabarcoding libraries of both sample types prepared from the exact same set of leaves also provides a new strategy to identify endophytes that may not be culturable. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Materials on Plant Leaf Surfaces Are Deliquescent in a Variety of Environments.

Materials on plant leaf surfaces that attract water impact penetration of foliar-applied agrochemicals, foliar water uptake, gas exchange, and stomatal density. Few studies are available on the nature of these substances, and we quantify the hygroscopicity of these materials. Water vapor sorption experiments on twelve leaf washes of sample leaves were conducted and analyzed with inductively coupled plasma-optical emission spectroscopy (ICP-OES) and X-ray diffraction. All leaf surface materials studied were hygroscopic. Oils were found on the surface of the Eucalyptus studied. For mangroves that excrete salt to the leaf surfaces, significant sorption occurred at high humidity of a total of 316 mg (~0.3 ml) over 6–10 leaves and fitted a Guggenheim, Anderson, and de Böer sorption isotherm. Materials on the plant leaf surface can deliquesce and form an aqueous solution in a variety of environments where plants grow, including glasshouses and by the ocean, which is an important factor when considering plant-atmosphere relations.

Species-specific efficiency in PM2.5 removal by urban trees: From leaf measurements to improved modeling estimates

The growing population in cities is causing a deterioration of air quality due to the emission of pollutants, causing serious health impacts. Trees and urban forests can contribute through the interception and removal of air pollutants such as particulate matter (PM). The dry deposition of PM by vegetation depends on air pollutant concentration, meteorological conditions, and specific leaf traits. Several studies explored the ability of different plant species to accumulate PM on leaf structures leading to the development of models to quantify the PM removal. The i-Tree Eco is the most used model to evaluate ecosystem services provided by urban trees. However, fine particulate matter (PM2.5) removal is still calculated with a poorly evaluated function of deposition velocity (which depends on wind speed and leaf area) without differentiating between tree species. Therefore, we present an improvement of the standard model calculation introducing a leaf trait index to distinguish the species effect on PM net removal. We also compared model results with measurements of deposited leaf PM by vacuum filtration. The index includes the effect of morphological and functional leaf characteristics of tree species using four parameters: leaf water storage, deposition velocity, resuspension rate and leaf washing capacity. Leaves of 11 common urban tree species were sampled in representative areas of the city of Ferrara (Italy) and at different times of the year from 2018 to 2021. This includes four deciduous broadleaf trees (Tilia cordata, Platanus acerifolia, Acer platanoides, Celtis australis), three evergreen broadleaf trees (Quercus ilex, Magnolia grandiflora, Nerium oleander), and four conifers (Thuja orientalis, Cedrus libani, Pinus pinaster, Picea abies). The results provide significant advancement in assessing PM removal using decision support tools such as models to properly select tree species for future urban tree planting programs aimed at improving air quality.

Influence of magnetized water irrigation on characteristics of antioxidant enzyme, ferritin, and Cd excretion in Festuca arundinacea during phytoextraction

The magnetic field can alter the hydrogen-bond structure and polarity characteristics of water; therefore, we hypothesize that magnetized water can affect plant physiological functions, including metal detoxification and excretion. In this study, the amount of Cd excreted on the leaves of Festuca arundinacea was estimated using magnetized water and normal water irrigation patterns. Irrigation with magnetized water improved the shoot dry weight and Cd content in F. arundinacea by 13.6% and 52.8%, respectively, compared to the control. Magnetized water irrigation also increased antioxidant enzyme activities in plant leaves, thereby alleviating the oxidative damage. The concentration of ferritin was 0.91 folds higher than that of the control, increasing the Fe sequestration and detoxification capacity of F. arundinacea. The amount of Cd excreted was significantly higher under magnetized water irrigation, thereby increasing the annual Cd removal by 109.7% from soil by leaf washing compared with that of the control. In contrast, F. arundinacea irrigated with magnetized water excreted 38.1% less Fe owing to the increase in ferritin levels, compared with that of the control. This study suggests a novel pathway of Cd phytoremediation by rinsing excreted Cd from the leaf surface without harvesting and replanting F. arundinacea.

DEVELOPMENT OF A MODULAR BITTER LEAF WASHING AND JUICE EXTRACTION MACHINE

Bitter leaf (Vernonia amygdalina) is one of the leafy vegetables that can be used to alleviate the problem of micronutrient malnutrition, prominent in tropical Africa. To ensure availability in non-growing areas, the vegetable needs to be preserved. Processing and preservation methods influence the nutrient content of the vegetables. This research work is therefore focused on the development of a modular bitter leaf washing and juice extraction machine. The machine is an electrically powered bitter leaf juice extractor that washes bitter leaf fed into it and at the same time squeezes out the juice. It uses stainless steel beaters inclined to angle of 0o to wash and squeeze the leaves against the cylindrical hopper incorporated with a perforated plate that drained juice while pulp is expelled. The beater is designed to work with the principle of oscillatory motion. The designed and fabricated bitter leaf juice washing and extraction machine was evaluated to determine the power, torque, force, etc., that are required to wash and extract the juice. The results obtained showed that the speed reduction, angular velocity, centrifugal force, torque, and power of 0.0127 m3, 480 rpm, 50.285 rad/sec, 303.430 N, 3.03 Nm, 0.75 hp are required. Also, a minimum bitter leaf extraction time of 398.28 seconds was required by the machine in comparison to manual extraction time of 724.13 seconds. Besides, the result of volume of bitter leaf juice extracted manually and mechanically from 407.54 g of bitter leaf were 3.60 litre and 3.63 litre respectively. The efficiency of the machine and the machine throughput capacity were obtained as 55.00 % and 1.032 g/sec respectively. This simply implies that the developed machine is 55.00 % efficient than manual method of washing bitter leaf.

The effectiveness of urban trees in reducing airborne particulate matter by dry deposition in Tehran, Iran.

Deposition of atmospheric pollution as particulate matter (PM) has become a serious issue in many urban areas. This study measured and estimated the amount of atmospheric PM deposition onto oriental plane (Platanus orientalis L.) trees located in Tehran Megapolis, Iran. PM deposited on the leaves of urban trees during spring and summer was estimated using leaf wash measurements. In addition to direct measurements, the dry deposition velocity and the yearly whole-tree PM deposition were estimated using both field measurements and a theoretical model of deposition flux. We estimated air quality improvement as a result of the trees at respiratory height (1.5m), tree height (10m), and boundary layer height (1719m). Foliar PM deposition during spring and summer was estimated to average 0.05g/leaf and 41.39g/tree using direct measurements. The annual PM deposited on the leaves, trunk, and branches of an average urban tree was calculated to be 78.60g/tree. Trees were estimated to improve air quality at 1.5m, 10m, and 1719m from ground level by 25.8%, 5.8%, and 0.1%, respectively. Hence, oriental plane trees substantially reduce PM at respiratory height.

Mycoflora Associated with Phylloplane and Rhizosphere of Aloe vera and their Effect on Plant Growth Parameters

The present investigation was conducted to study the spectrum of mycoflora associated with phylloplane and rhizosphere of Aloe vera and to assess their effect on plant growth parameters and antagonistic activity against the C. gloeosporioides causing black spot disease in Aloe vera. During the study total 15 mycoflora belonging to ten genera were isolated from Aloe vera plant by leaf washing technique from phylloplane and serial dilution from rhizosphere soil. Among these, fungal species belonging to the genera of Aspergillus, Trichoderma and Penicillium was found to be more abundant. In course of study some of mycoflora associated with phylloplane and rhizosphere of Aloe vera were found to exert plant growth promoting effect and also exhibited strong antagonistic activity against Colletotrichum gloeosporioides.

Tree phyllospheres are a habitat for diverse populations of CO-oxidizing bacteria.

Carbon monoxide (CO) is both a ubiquitous atmospheric trace gas and an air pollutant. While aerobic CO-degrading microorganisms in soils and oceans are estimated to remove ~370 Tg of CO per year, the presence of CO-degrading microorganisms in above-ground habitats, such as the phyllosphere, and their potential role in CO cycling remains unknown. CO-degradation by leaf washes of two common British trees, Ilex aquifolium and Crataegus monogyna, demonstrated CO uptake in all samples investigated. Based on the analyses of taxonomic and functional genes, diverse communities of candidate CO-oxidizing taxa were identified, including members of Rhizobiales and Burkholderiales which were abundant in the phyllosphere at the time of sampling. Based on predicted genomes of phyllosphere community members, an estimated 21% of phyllosphere bacteria contained CoxL, the large subunit of CO-dehydrogenase. In support of this, data mining of publicly available phyllosphere metagenomes for genes encoding CO-dehydrogenase subunits demonstrated that, on average, 25% of phyllosphere bacteria contained CO-dehydrogenase gene homologues. A CO-oxidizing Phyllobacteriaceae strain was also isolated from phyllosphere samples which contains genes encoding both CO-dehydrogenase as well as a ribulose-1,5-bisphosphate carboxylase-oxygenase. These results suggest that the phyllosphere supports diverse and potentially abundant CO-oxidizing bacteria, which are a potential sink for atmospheric CO.

Factors influencing the performance of phosphites on the control of coffee leaf rust

ABSTRACT This study investigated the effect of different phosphites on the control of coffee leaf rust (CLR) caused by Hemileia vastatrix, considered the major disease affecting coffee yield worldwide. Three-month-old coffee plants were sprayed with two doses each of the phosphite solutions (standar., and double), as follows: K (40% P2O5; 1.., and 3 mL∙L-1), K (30% P2O5; ., and 6 mL∙L-1), Cu (2.., and 5 mL∙L-1), Mn+Zn (., and 6 mL∙L-1., and Na (., and 6 mL∙L-1) 24 h before being inoculated with H. vastatrix. Leaves were not washed or washed with deionized water after the foliar phosphites spray. Plants sprayed with water served as the control treatment. Inoculation was performed on the abaxial side of the first pair of expanded leaves using a camel hairbrush with a suspension of urediniospores (1 mg per leaf). All phosphites applied at the standard doses (from 1.5 to 3 mL∙L-1) reduced the total number of pustules (TNP) per leaf by 28-69% regardless of washing treatment. The biggest reductions were observed for Cu phosphite, which decreased the TNP per leaf by 6., and 69% withou., and with leaf washing, respectively. A similar trend was observed when the double doses of phosphites (from 3 to 6 mL∙L-1) were used, though Na phosphite without leaf washin., and Mn/Zn phosphite withou., and with leaf washing were not efficient to reduce the TNP per leaf. Without leaf washing, only C., and Na phosphites decreased CLR severity at the standard doses (53-61%), whereas all phosphites, except the Mn/Zn phosphite, reduced CLR severity at the double dose. The CLR severity was decreased using K 30%, K 40., and Cu phosphites when applied at the standard doses with leaf washing (41-59%). With double doses, only C., and Na phosphites decreased CLR severity by 55% for both treatments. In conclusion, the efficiency of the phosphites for CLR control varied according to the accompanying cation, dos., and washing conditions. The Cu phosphite resulted in the best CLR control regardless of the dose use., and the washing conditions.

Combined measurements of microscopic leaf wetness and dry-deposited inorganic compounds in a spruce forest

Hygroscopic particulate salts on leaf surfaces may facilitate the formation of microscopic leaf wetness, wax degradation, and enhanced of trace gas exchange in forest environments. In order to investigate the interaction of microscopic leaf wetness and dry-deposited inorganic compounds, a field campaign that combined measurements using electrical conductance sensors and leaf washing techniques was carried out in a coniferous forest in Germany during the summer period. Within the canopy, electrical conductivity was directly and continuously measured across a needle surface exposed to the air and covered with branches. Inorganic ion concentrations of washed samples at the top and middle of the canopy were measured and used to estimate leaf-level dry deposition rates of inorganic compounds. The results of both electric conductance and washed ion concentrations indicated the presence of deposited salts on needles within the canopy. Sulfate (SO42−) and nitrate ions (NO3−) were dominant among soluble mass compounds in washed samples. A higher deposition rate of oxidized nitrogen (measured as NO3−) was estimated at the top of the canopy (0.59 μmol m−2 h−1) than in the middle (0.15 μmol m−2 h−1), indicating that dry deposition of oxidized nitrogen mainly occurs near the canopy top. The deliquescent behavior of deposited hygroscopic salts was suggested by a hysteresis effect depending on increasing or decreasing relative humidity in our leaf wetness measurements. The results indicate that deposition of atmospheric inorganic compounds on needles and leaves can facilitate the formation of leaf wetness on the vegetation surface.

Innovative Characterization of Particulate Matter Deposited on Urban Vegetation Leaves through the Application of a Chemical Fractionation Procedure.

In this study, we have evaluated the efficiency of a chemical fractionation procedure for the characterization of both the water-soluble and the insoluble fraction of the main elemental components of particulate matter (PM) deposited on urban leaves. The proposed analytical approach is based on the chemical analysis of leaf washing solutions and membrane filters used for their filtration. The ionic concentration of leaf washing solutions was compared with their electrical conductivity, making it a valuable proxy for the quantification of the water-soluble and ionic fraction of leaf deposited PM. The chemical composition of both the water-soluble and the insoluble fraction of PM, resulting from this fractionation procedure, was compared with results obtained by scanning electron microscopy coupled with energy-dispersed X-Rays spectroscopy (SEM/EDX) and processed through chemometrics. Results obtained proved that the proposed approach is able to provide an estimation of total leaf deposited PM and it is highly reliable for the evaluation of the emission impact of different PM sources, being able to increase the selectivity of PM elemental components as specific source tracers; consequently providing useful information also for the assessment of human health risks.

Assessment of particulate matter deposition on tree species near Marudhamalai region

A survey of five dust polluted plants of different families Azadirachta indica, Pongamia pinnata, Ficus religiosa, Ficus benghalensis, Polyalthia longifolia were carried out in Marudhamalai Road, Coimbatore, India. The dust holding capacity of leaves, pH of dust wash of leaf surface and amount of total chlorophyll content with respect to dust deposition on leaves are determined. From the surveyed plants the quantity of dust deposition was recorded from the randomly sample leaves. The maximum dust deposition on leaf surface was recorded in Polyathia longifolia and minimum dust deposition was found on Ficus religiosa. The pH of leaf wash of dust was found maximum on dust polluted leaves as compared to the control. The minimum total chlorophyll content was recorded in dust affected leaves. The dust deposition may different according to the structure, area, roughness, hair growth in surface of leaves. The dust may clogs pores of the stomata, it leads to change in respiration and transpiration process, no photosynthesis will occur and no food will be made hence tree will die off.

Immobilized atmospheric particulate matter on leaves of 96 urban plant species.

Plants provide many ecosystem services in urban environments, including improving ambient air quality. Leaves of plants permit the deposition of particulate matter (PM) and, depending on their leaf traits, PM may be immobilized within the epicuticular wax (EW) layer, on trichomes, on hyphae of fungi, or inside stomatal cavities. In this study, leaves of 96 perennial urban plant species consisting of 45 deciduous broadleaf/needle-like trees, 32 deciduous broadleaf shrubs, 12 evergreen needle/scale-like trees, 5 evergreen broadleaf trees, and 2 climber species were investigated in June and September 2016 to determine the effectiveness of distinct leaf surfaces in PM immobilization after leaf washing treatment. The leaf surfaces were washed vigorously using a vortex shaker. The magnetizable component of accumulated and immobilized PM on the leaf surfaces was estimated using saturation isothermal remanent magnetization (SIRM) of the unwashed and washed leaves, respectively. In June, the washed leaf SIRM of deciduous (broadleaf/needle-like) tree and shrub species (n = 77) ranged between 0.1 and 13.9 μA. In September, the washed leaf SIRM of all investigated plant species (n = 96) ranged between 1.2 and 35.0 μA. Outcomes of this study indicate that leaves of Buddleja davidii, Viburnum lantana, and Sorbus intermedia showed the highest washed leaf SIRM and thus were the most effective in immobilizing PM on their leaf surfaces while leaves of Populus alba, Robinia pseudoacacia, and Abies fraseri with lowest washed leaf SIRM were the least effective. On average, more than half (i.e., 60%) of the magnetic signal still remained after vigorous washing but a large variation exists between species (9-96%). The leaf SIRM of washed leaves of deciduous broadleaf tree and shrub species was significantly higher compared to leaves of evergreen needle/scale-like species. Evidently, the magnetic signal of unwashed leaves was higher than washed ones and higher in September than in June. Leaf traits significantly influenced the magnetic signal of both washed and unwashed leaves: leaves with a high trichome density or high leaf wettability showed a higher unwashed and washed leaf SIRM compared to leaves with no trichomes or low leaf wettability. The effect of epicuticular wax structure types on leaf SIRM was indicated to be only marginally significant. Moreover, also the immobilized fraction of PM was significantly affected by trichome density and leaf wettability, thus substantiating that plant species with high trichome density and/or leaf wettability not only accumulate more PM but are also less prone to PM re-suspension than other species. In general, the results also indicate that leaf SIRM of unwashed leaves can be a good indicator to determine the effectiveness of a plant species in PM immobilization. Plant species effective in immobilizing PM on their leaf surfaces may likely improve ambient air quality when planted in urban environments. However, it is vital that leaves of these plant species (i.e., with high PM immobilization abilities) are carefully recycled as they may be polluted.

The effect of applying fertilizer of moringa leaf (Moringa oliefera) extract and rice washing water to the growth of pakcoy plant (Brassica rapa L. spp. Chinensis (L.))

The hydroponic system is increasingly popular in Indonesia. In 2014, 597,674 tons of pakcoy were harvested from hydroponic products. However, the hydroponic system uses mix AB fertilizer which is relatively expensive. Moringa leaf and rice washing water have high mineral and vitamin content. There are cytokinin in moringa leaves which are useful for growth so that they can be used as organic liquid fertilizer. This study aims to determine the response of pakcoy growth to the provision of organic liquid fertilizer made from moringa leaves and rice washing water which is relatively cheap. Organic liquid fertilizer is made through the process of moringa leaf fermentation and rice washing water. The treatment given is in the form of 40% AB mix and 60% fermented organic liquid fertilizer. This treatment showed the results in the form of increased leaf size, number of leaves, stem diameter and weight per sample. The addition of organic liquid fertilizer to Pakcoy resulted in an increase in leaf width and length, number of leaves and weight per sample.

Assessing atmospheric dry deposition via water-soluble ionic composition of roadside leaves

This study focuses on the water-soluble ion concentrations in the washing solution of leaves of different roadside tree species at three sites in Iran to estimate the ionic composition of the dry deposition of ambient air particulates. All considered water-soluble ion concentrations were significantly higher next to the roads with high traffic density compared to the reference site with low traffic density. The PCA results showed that Ca2+, Mg2+, and originated mainly from traffic activities and geological sources, and Na+, Cl−, K+ and F− from sea salts. In addition to sea salt, K+ and F− were also originated from anthropogenic sources i.e. industrial activities, biomass burning and fluorite mining. Moreover, the concentration of the water-soluble ions depended on species and site. C. lawsoniana had significantly higher ion concentrations in its leaf washing solution compared to L. japonicum and P. brutia which indicates C. lawsoniana is the most suitable species for accumulating of atmospheric dry deposition. From our results, it can be concluded that sites with similar traffic density can have different particle loads and water-soluble ion species, and that concentrations in leaf-washing solutions depend on site conditions and species-specific leaf surface characteristics.

Environmental safety of residential and public areas in the context of PM2.5, PM10 monitoring on the leaves of apricot trees (Prunus armeniaca)

Introduction. Fine dust puts human health at risk in populated areas. The research is focused on dust particles on the leaves of apricot trees (Prúnus armeníaca) in the residential area of the Central Akhtuba district of the Volgograd region (the area of single family houses and low rise townhouses) and in the public area (the area of public amenities) located in close proximity to construction and development enterprises, machine builders, etc. as compared to the dispersion composition of dust on the leaves of apricot trees (Prúnus armeníaca) in the territory occupied by rural housing communities in the conditionally clean zone (the benchmark zone) in absence of any man-induced loadings coming from industrial facilities (Oroshenets gardeners’ non-commercial partnership, Volgograd, Soviet district). The goal of the research is to study the dispersion composition of dust and to identify fine dust PM2.5 and PM10 using plant monitoring systems in the residential area. The objectives include the sampling of dust particles from plant leaves, dust analysis, and identification of areas exposed to ecological risks.&#x0D; Materials and methods. The leaves of apricot trees (Prúnus armeníaca), growing in residential and public areas of the Central Akhtuba district of the Volgograd region and in the territory of Oroshenets gardeners’ non-commercial partnership, Volgograd, Soviet district (the conditionally clean benchmark zone) represent the study material. Methods of research include leaf wash into the beaker full of distilled water, suspension filtration using AFA-VP analytical filter, filtrate production and natural drying at the temperature not exceeding 30–40 °C, and placement of the dried filtrate on the slide of an optical microscope. The distribution of dust particles was performed pursuant to State Standard of Russia 56929-2016.&#x0D; Results. The co-authors have identified the zones exposed to ecological risks in residential and public areas of the Central Akhtuba district of the Volgograd region (Bolnichnaya st., residential houses in Nechayeva, Omskaya streets, a kindergarten in Kavkazskaya st.: PM2.5, PM10) and safe residential areas (a boarding school in Vorovskogo st.: PM10 — 20 μm and 20–40 μm).&#x0D; Conclusions. Further studies of residential and public areas of the Central Akhtuba district of the Volgograd region are to be performed to identify the chemical composition of dust particles and the source of fine dust polluting the air and to develop a roadmap of environmental actions.

Antagonistic activity of phylloplane yeasts from Moringa oleifera Lam. leaves against Aspergillus flavus UNJCC F-30 from chicken feed

Aspergillus flavus is widely known as an aflatoxin-producing fungus that frequently contaminates feed and affects livestock, which leads to severe health problem for animal and human. Biological agents have been proven to prevent this contamination since they can produce metabolites which have antagonistic activity. In this study, phylloplane yeasts isolated from Moringa oleifera leaf have shown an ability to inhibit the growth of Aspergillus flavus UNJCC F-30 collected from chicken feed. This research was conducted in three stages: (1) yeast isolation (leaf washing and direct method), followed by (2) antagonistic test using dual culture method, and (3) molecular identification using D1/D2 region of 26S rDNA. In the first stage, 38 yeast isolates have been succesfully obtained. These isolates were of different colors: peach pigment (60.5%), the non-pigmented yeast (26.5%), cream (10%), and orange (3%). Antagonistic activity against A. flavus UNJCC F-30 was tested based on growth, sporulation, and the presence of clear zones. Screening result showed that 12 yeast isolates are capable of inhibiting A. flavus UNJCC F-30. Among them, 4 isolates with the code K4, K10, K15, and K26 showed the highest antagonist ability. Molecular identification resulted that the 4 isolates show a similar identity with Aureobasidium pullulans UWFP 993 (100%), Aureobasidium melanogenum QCC:M017/17 (99%), Aureobasidium melanogenum QCC:M017/17 (100%) and Rhodotorula taiwanensis CBS:11729 (99%), respectively. Isolate K10 exhibited the highest percentage of inhibition activity among all isolates which is potential for application as biocontrol agent against A. flavus. As A. pullulans is a common yeast found on leaf surfaces of many Indonesian flora, therefore it can be considered as safe and alternative to reduce fungal contamination from A. flavus in feed chicken.