Search

Vegetation provides direct information to interpret the environment, ecology, climate and deposit of a site. The identification of the surrounding vegetation from root marks recorded on the surface of skeletal elements is a new source of information of special interest. This article is a preliminary approach to relate root marking (i.e. taphonomic effect) recorded on bone surfaces caused by plants (i.e. taphonomic agent) through an experimental model. Distinguishing the root marks of one type of plant from marks produced by any other type of plant is an investigation that has been neglected in taphonomy. The preliminary results described here represent the starting point of this research field. This is an experimental work that is currently in progress, and further studies will include higher sample sizes and the analysis of different specimens in contact with other plants such as shrubs and trees. Our preliminary results shown here come from three different root plant types (underground, subaerial and aquatic) displaying characteristic differences that reinforce the need of extending this research and the importance of the analysis of this taphonomic modification. [ABSTRACT FROM AUTHOR]

Two new genera and one new species of Tegonotini (Acari: Eriophyoidea) from China are described and illustrated. They are Multispinacarus dimocarpigen. nov. & sp. nov. infesting Dimocarpus longan Lour. (Sapindaceae), Alvetegonotus calleryagen. nov. & sp. nov. infesting Callerya tsui (F. P. Metcalf) Z. Wei & Pedley. (Fabaceae), and Shevtchenkella sterculiaesp. nov. infesting Sterculia euosma W. W. Smith. (Malvaceae). These new species were found to be vagrants on the lower leaf surface of their associated plants, albeit with no apparent damage observed. The article corresponds to The new genera Multispinacarus Lian, Ren, Tan, Luo et Wang corresponds to The new genera Alvetegonotus Lian, Ren, Tan, Luo et Wang corresponds to The new species shevtchenkella sterculiae Lian, Ren, Tan, Luo & Wang, corresponds to [ABSTRACT FROM AUTHOR]

The present study synthesised and characterised zinc oxide nanoparticles (ZnO NPs) using spinach tree, Cnidoscolus aconitifolius and investigated its potential use as nanofertilizer. The synthesised nanoparticles showed UV-Vis absorption peak at 378nm which is a feature of ZnO NPs. FT-IR analysis further revealed the presence of O-H stretching, C=C bending, O-H bending and C-N stretching functional groups of the stabilising action of the plant extract on the surface of the nanoparticles. SEM images displayed the shape of NPs to be spherical whereas TEM images showed their distribution sizes to be 100 nm. Synthesised ZnO NPs were used as a nano fertilizer on Sorghum bicolour plant. An increase in the shoot leaf length with an average length of 16.13 ± 0.19 cm as compared to the control group of 15.13 ± 0.07 cm was observed. The rate of photosynthesis also showed a significant increase with total chlorophyll content of 0.2806 ± 0.006mg/mL as compared with control of 0.2476 ± 0.002 mg/mL. The activity of antioxidative enzymes was measured with an increase in the specific activity of SOD in the plant when ZnO NPs were used over NPK whereas, the specific activities of CAT were similar in all cases. [ABSTRACT FROM AUTHOR]

Introduction. Phymatoceros Stotler et al., one of the 14 extant genera of hornworts, is known from only two species worldwide. During our studies of Indian hornworts, a distinctly variable population was found at Binsar, Uttarakhand, and sharing the same habitat as Phaeoceros himalayensis (Kashyap) Prosk. ex Bapna & G.G.Vyas and Phaeoceros laevis (L.) Prosk. Methods. A critical study of the specimens housed at CSIR-NBRI, Lucknow (LWG) was conducted. An SEM study of spores was also carried out to examine their ultramorphological characters. Key results. The plants were found to be remarkably characterised by a narrow thallus with prolific stalked tubers arising from the mid-ventral surface; female plants with short involucres; single rounded to irregular chloroplast per cell, without a pyrenoid; and spore distal face with a large, central, single, pitted central hump, and the proximal face with a distinct single dimple on each tetrahedral area between triradiate rays. A detailed morphotaxonomic account is presented, along with detailed SEM observations of spores of the Indian plants. Conclusion. Our critical comparative study has revealed that the plants of the newly recorded population belong to the genus Phymatoceros and are distinct from hitherto known species. They are described here as a new species, Phymatoceros binsarensis A.K.Asthana, D.Shukla & Reesa Gupta, and are the first record of Phymatoceros in India. As such, they represent a remarkable and interesting disjunct occurrence of the genus in Asia, separate from its distribution in four other continents (Africa, Europe, and North and South America). [ABSTRACT FROM AUTHOR]

The majority of animals possess claws on their legs and they are mainly used for keeping attached to the substrate. Recent studies on claw shapes and function suggest that claws are not just simple attachment devices but highly specialized morphological traits bearing information about lifestyle, ecology and evolution. In that respect, knowledge about claws is extremely scarce, especially in highly diverse groups, as for example the oribatid mites, with more than 11000 named species occurring in every environment all over the world. This review summarizes all information about claws and relevant aspects for this large group of arthropods. There is a huge variety of ambulacral claw morphologies present in oribatid mites and this diversity does not follow a strict phylogenetic or systematic pattern. Lifestyle and ecology apparently play an important role in shaping claw morphologies. Intertidal oribatid mites are mostly characterized by having single large tarsal claws to withstand tidal flooding, a similar tendency can be found in terrestrial limnic species where monodactylous species prevail. Additionally, fresh-water Oribatida often show scaliform and barbed distal tarsal setae which cooperate with the claws helping the mites to stick to water plants. Claws of arboreal mites are often equipped with adhesive pads "pulvilli" allowing them to walk on smooth plant surfaces. Suction pads are also found in a few mites showing epilithic lifestyles and in mites being able to perform sudden evasive jumps. Claws of phoretic oribatid mites show in most cases no apparent adaptations but certain groups are equipped with highly modified claws allowing them to attach to specific structures of their hosts. Finally, this review gives an overview of all claw morphologies present in each larger phylogenetic oribatid mite group. [ABSTRACT FROM AUTHOR]

This study aims to biosynthesize zinc oxide nanoparticles using aqueous leaf extracts of Cnidoscolus aconitifolius and investigate their biological activities. UV–Vis Spectroscopy, FT-IR, SEM and TEM were used for characterization. The antioxidant properties were determined using H2O2, NO, ABTS, FRAP and DPPH scavenging assays. For anti-inflammatory activities, membrane stabilization, albumin denaturation and proteinase inhibitory activity were assayed. The antibacterial effect was tested using well diffusion method. Statistical analyses were done using ANOVA. Synthesized nanoparticles showed an intensity peak at 378 nm in UV–Vis Spectroscopy. FT-IR shows the presence of O-H stretching, C = C bending, O-H bending and C–N stretching functional groups of the stabilizing action of the plant extract on the surface of the nanoparticles. NPs were shown to be spherical by SEM analysis, and the sizes were 100 nm by TEM analysis. The antioxidant properties of ZnO NPs compared to ascorbic acid standard showed significant antioxidant potential in H2O2, NO, ABTS, FRAP and DPPH scavenging assays. ZnO NPs showed excellent anti-inflammatory activity with the synthesized ZnO NPs performing better in membrane stabilization. Clinical pathogens were inhibited by ZnO NPs when compared with Cefuroxime, a standard drug. These efficient biological activities could be utilized in several biological applications. [ABSTRACT FROM AUTHOR]

Pesticide residues on plant surfaces are a primary source of pesticide bioaccumulation in crops. In this context, we propose a mechanism-based model for understanding the pesticide fate on the plant surface following aerial application, taking into account fate modelling of the pesticide spray solution on the plant surface. Using chlorothalonil as an example, the simulation results revealed that the spray solution dissipated rapidly after aerial application, resulting in the formation of a saturated pesticide solution, which facilitated the diffusion process of the pesticide residue from the plant surface into the peel tissue. The proposed model generated higher simulated residue concentrations in the peel or pulp than the current model, owing to the proposed model's assumption of rapid dissipation of the spray solution. This indicated that the proposed model specified the influence of the spray solution on the plant's exposure to residues via the surface deposition pathway, whereas the current modelling approach presented a generic estimate of the residue dissipation on the plant surface that linked to the residue's fate in the soil. [ABSTRACT FROM AUTHOR]

This research aims to optimize the influential hydrodynamic parameters in liquid-liquid extraction columns for three different systems of butanol–water, n-butylacetate–water, and toluene–water recommended by the European Federation of Chemical Engineering. The operating conditions of rotor speed, continuous phase, and dispersed phase velocities and two responses of the dispersed phase holdup of dispersed phase and Sauter mean drop diameter are considered to examine their interaction effects in a perforated rotating disc contactor (PRDC) pilot plant by response surface methodology (RSM). A desirable consistency between the predicted and experimental data was observed due to an R2 value higher than 0.99. The maximum dispersed phase holdup and minimum Sauter mean drop diameter (d32) were obtained at 0.117 and 0.599 mm, respectively. The results pointed out that the rotor speed is the most substantial variable in the studied responses. [ABSTRACT FROM AUTHOR]

The study focused on exposure assessment to bacterial aerosols and organic dust in waste sorting plant. Samples were collected at different workplaces of waste sorting cycle i.e.: waste press, reloading area, loading of conveyor belt, sorting cabin, sorting hall, and control room. A quantitative analysis of aerobic and anaerobic bacteria was supplemented by qualitative analysis of anaerobic biota with the use of culture-based methods and biochemical tests. In addition, inhalable dust concentrations were also evaluated. To confirm the presence of Clostridium genus, the PCR reaction with specific primers (Chis150f and ClostIr) was performed. The average concentration of total bacteria in waste sorting plant was 4347 CFU m−3 (SD = 2439), of which 66% were anaerobic strains (2852 CFU m−3; SD = 2127). It was found that about 24% of anaerobic bacteria belonged to Clostridium genus (682 CFU m−3; SD = 633). The highest contamination with anaerobic bacteria was observed near the waste reloading plant (3740 CFU m−3), and the lowest in the control room (850 CFU m−3). The average concentration of inhalable dust in the waste sorting plant was 0.81 mg m−3 (SD = 0.59). The correlation analysis showed that the presence of anaerobic bacteria, including clostridia was significantly determined by the microclimate parameters. Qualitative analysis showed the presence of 16 anaerobic species belonging to 9 genera, of which Actinomyces, Clostridium, and Gemella were present at all workplaces. The molecular analysis confirmed the presence of Clostridium genus in both bioaerosol and settled dust samples. Implications: The study showed that anaerobic bacteria should be taken into account as an important component of this microbiota when assessing the exposure of waste sorting workers to biological agents. However, future studies should investigate more precisely how the composition of sorted waste as well as the season can affect the diversity of anaerobic bacteria in this working environment. More attention should be paid to regular cleaning of equipment surfaces in the plant, as deposited organic dust is an important reservoir of anaerobic bacteria, including those of a potentially pathogenic nature. [ABSTRACT FROM AUTHOR]

Using remote sensing technology for exploring the trait of interest can provide better results without damaging the plants and are comparatively economic. Traditional methods are available for quantification of different pigments and chemicals present in plants, yet these methods do not allow repeated measurements on the same plant throughout development. The reflected values from plant surfaces are a direct representation of plant physiology including plant morphological factors. The hyperspectral imaging indices for vegetation and water-stressed canopies provided a better indication of each genotype proficiency, thus improving their selection efficiency. The presence of epicuticular wax (EW) influences the reflectance from leaf surface which depends on the presence of leaf pigments including carotenoids, photosynthetic light use efficiency biochemical structures, and water content as they absorb the incident light necessary for photosynthesis. The results obtained suggested decrease carotenoid reflectance index (CRI) and photochemical reflectance index (PRI) values for high wax lines indicating the low concentration of stress-related pigments thus improving plant health and extended maturation. The high waxy lines decreased for plant senescence reflectance index (PSRI) and reduce canopy stress at grain filling and maturation growth stages. A positive correlation between high epicuticular wax (EW) and yield was found confirming previous study. A positive correlation between high epicuticular wax (EW) lines and yield indicated its important role in preventing yield losses under drought conditions. [ABSTRACT FROM AUTHOR]

Beauveria bassiana, known for its entomopathogenic characteristics, is the most widely used biocontrol agent against many insect pests and may also be active against soil-borne pathogens. It inhabits the surfaces or inner tissues of various plant species without causing any visible signs or symptoms. Here we show that B. bassiana strain GHA, the active ingredient of a commercial microbial insecticide, colonises tomato plants. GHA grew on intact leaf surfaces of tomato in high humidity, but never entered stomata. Viable hyphae and conidia were detected, and the population on inoculated leaves significantly increased until 14 days after inoculation. On tomato leaves, GHA conidiated normally via conidiophores and phialides, and also via microcycle conidiation (conidiophores and phialides form directly from germ tubes and produce conidia). Hyphae were also detected inside the rachis, even more frequently after plant surfaces were scarified. These results suggested that B. bassiana strain GHA can grow epiphytically and endophytically on tomato plants. [ABSTRACT FROM AUTHOR]

Water temperature is fundamental to understand the functioning of aquatic systems. The objective of this study was to assess the effect of warm water discharge from a nuclear power plant on the water surface temperature (WST) of a reservoir. Using a 6-year Landsat-derived WST dataset, which includes 3 years of the power plant being in operation (2013–2015) and 3 years in which the power plant was not functioning (2016–2018), the effect of the thermal pollution was assessed. The results show that, although the warm water discharge did not reveal a statistically significant increase on the mean WST of the reservoir (p > 0.05), multi-temporal Landsat imagery revealed that the power plant generated a local thermal impact. This was the principal heat flux following a dissipation line that was wide near the cooling channel and expanding towards the rest of the reservoir. [ABSTRACT FROM AUTHOR]

Fly-speck fungi reproduce via thyriothecia that consist of sporogenous tissue appressed to cuticle surfaces of plant leaves and covered by a shield-like scutellum. Thyriothecial scutella likely evolved repeatedly in Dothideomycetes (Ascomycota), and their morphology varies by lineage. Fly-speck fungi have an exceptionally good fossil record that begins in the Mesozoic. The interpretation of scutellum characters in fossils may provide insights into origins of Dothideomycetes and help calibrate the timing of ascomycete evolution. From sediments of the Lower Cretaceous (125–112 Ma) Potomac Group of Virginia, from Dutch Gap Canal, lower Zone 1, we found scutella similar to those of extant Aulographaceae (Dothideomycetes), attached to a single piece of dispersed coniferous cuticle. We analyze hyphae and scutellum development among four extant Aulographaceae species for comparison with the fossil. The excellent preservation of fungi on the leaf cuticle surface allows us to infer a developmental sequence for the fossil. Scutellum development begins with coordinated growth of multiple neighboring generator hyphae and continues with hyphae producing two-dimensional pseudomonopodial, dichotomous, radial growth. Asci and ascospores were not found. We coded states for seven morphological characters using direct observations of the fossil and eight extant taxa, and using the literature for 28 others. We inferred a phylogeny using nuclear 18S and 28S rDNA of 36 extant taxa, 34 Dothideomycetes and two Arthoniomycetes. The phylogeny includes newly determined sequences from five species, two from Aulographaceae. With a branch-and-bound search, we inferred the most parsimonious placements of the fossil given the molecular tree topology. The parsimony analysis constrained by the rDNA phylogeny places the fossil taxon among stem lineages near Aulographaceae or among the known living members of Aulographaceae. We describe the fossil morphotype as Protographum luttrellii, gen. et sp. nov. The fossil provides the oldest evidence of morphological characters restricted among extant fungi to Aulographaceae. [ABSTRACT FROM AUTHOR]

Poor productivity of rice in rainfed lowlands is due to complete submergence as it is a major abiotic stress of these regions. For enhancing the rice productivity of these areas, better nutrient management options are required and results may even better when combined with stress tolerant cultivars, even when tested under natural conditions of farmers' field. For supporting the above statement, the effect of nitrogen and phosphorus in graded doses was evaluated for submergence tolerance in controlled conditions and the results obtained were tested and validated at farmers' field in Cuttack, Odisha, India. Shoot elongation, leaf senescence and lodging were lowest with the application of higher phosphorus (60 kg ha−1). Highest dose i.e. 100-60-40 NPK kg ha−1 resulted in higher plant survival of all the varieties by 90–170% over no nutrient application, it was also reflected in the higher growth after recovery, leaf greenness, leaf and stem growth, chlorophyll and carbohydrate concentrations and ultimately higher grain yield. At farmers' field, application of basal P, K and post-flood N management practice resulted in overall better performance of Swarna and Swarna-Sub1 showing higher yield attributes leading to 65.7 and 37.9% higher grain yield, over conventional practices followed by farmers. Apart from that results were more positive if post-flood nitrogen was applied as urea foliar spray might be due to quick absorption of N by plant leaves and also spraying helps in removing the silt of flood water sticking to the leaf surface and facilitated the plants to photosynthesize and survive after desubmergence. These cost-effective management options may enhance the productivity and profitability of rice in the flood-prone areas where farmers hesitate to apply nutrients. [ABSTRACT FROM AUTHOR]

Scientists have effectively proved that vegetative environment buffers (VEBs) can be used for reducing dust emissions from livestock buildings, but they have seen fewer tests in poultry farms. A field research was conducted to assess the effectiveness of VEBs on reducing downwind transport of particulate matter (PM) from a ventilated poultry house in Changchun. Five plant species transferred from local area were used to establish five diverse VEBs and separately installed outside of the ventilation fans in summer 2017. The five plant species were Winged Euonymus (WE), Malus Spectabilis (MS), Padus Maackii (PAA), Acer Saccharum Marsh (ASM), and Padus Virginiana "Red Select Shrub" (PV_RSS). The mass concentrations of PM2.5 and PM10 (particulate matter with an aerodynamic diameter of 2.5 μm and 10 μm or less, respectively) were monitored at downwind and upwind sampling locations around the VEB. The results showed that with the presenting of VEBs, the particle concentrations at the downwind sampling point were significantly reduced compared with that at the upwind sampling point (p < 0.05). Specifically, compared to the control test without VEB, the VEB with PV_RSS had the best PM concentration reduction rate (CRR) of 47.24%±4.33% and 41.13%±5.83% for PM2.5 and PM10, respectively. The rough surface of plant leaves may help intercept more PM, though it was also affected by other factors (such as the blade angle, the interaction with wind) needed to be further investigated. The VEB with PV_RSS, which presented the best capacity of CRR, selectively intercepted PM, mainly related to the elements of N, Na, Mg, P, S, and Cl. Implications: Five plant species, including WE, PAA, MS, ASM, and PV_RSS, were evaluated as VEBs to mitigate particulate emissions from outside of a ventilated poultry house in Changchun. They all significantly reduced particulate matter emissions. However, the PV_RSS presented the best capability of trapping fine and coarse particles: PM2.5 and PM10, respectively, while the PAA was the worst one. The microstructure of leaves affected particle deposition and remaining on the leaves, and PV_RSS selectively intercepted particulate matter mainly related to certain elements. [ABSTRACT FROM AUTHOR]

Combining surface evaporation and plant transpiration, evapotranspiration (ET) is critical to surface water and heat balances as it links water, carbon cycles and energy exchanges. Many models have been developed and are presently used to estimate terrestrial ET. However, there are large model uncertainties among the different models, which present a problem. By combining meteorological reanalysis data from the China Meteorological Forcing Dataset (CMFD) with remote sensing data and observational data during 2002-2009, two semi-physical models, the modified satellite- based Priestley-Taylor (MS-PT) model and a semi-empirical Penman equation-based (SE-PM) model, are used to estimate ET and are validated using in situ measurements collected at 22 flux tower sites in China. Then support vector machine (SVM) method is used to integrate these two semi-physical models to improve the accuracy of ET estimates for eight different vegetation types separately, as well as all of these types together. The integrated model likely explains 56-94% of the land surface ET changes indicated by the observations collected at the flux tower sites. The ET predictions obtained by driving the models with the reanalysis data (for which the relative bias and the relative root mean square error (RMSE) for all types of the SVM were 6 and 51 W m-2, respectively, and the maximum decrease of the relative RMSE for different types is nearly 20 W m-2) are less accurate than those obtained by driving the models with the observational data (for which the relative bias and the relative RMSE for all types of the SVM are 4 and 43 W m-2, respectively). Compared to the individual semi-physical models, the results produced by the integrated model display significantly decreased bias (less than 5 W m-2 for all types) and RMSE (for which the maximum decrease is nearly 71 W m-2) in the validation. [ABSTRACT FROM AUTHOR]

Plant surface is colonised with a vast community of non-pathogenic epiphytic microorganisms which play an important role in host defence. In the present study, we reported a fungus from mulberry leaf surface that showed an antagonistic effect against mulberry powdery mildew fungal pathogenPhyllactiniasp. This novel isolate is a yeast-like fungus that was identified asPseudozyma aphidisCNm2012 based on morphologic and phylogenetic analysis. According to our research,P. aphidisCNm2012 directly acted on the powdery mildew conidia via parasitism which caused conidial atrophy, collapse and eventually, cleavage and death. During the parasitic process, we found the isolate could gather around the conidia ofPhyllactiniasp. and form hyphae that grew on the conidial surface and utilise the conidia as a nutrient source. Field studies revealed thatP. aphidisCNm2012 could suppress the disease incidence of mulberry powdery mildew caused byPhyllactiniasp., and reduce the disease severity. To our knowledge, it is the first report ofP. aphidisdirectly against powdery mildew fungusPhyllactiniaspp. by parasitism. Our results indicated thatP. aphidisCNm2012 could be served as an environmentally friendly alternative of chemical pesticides to manage mulberry powdery mildew disease. [ABSTRACT FROM AUTHOR]

In the present study, seeds of 13OxytropisDC. species (including two latest synonyms) classified in subg.Oxytropis(sect.Dolichocarpon, sect.Chrysanthaand sect.Eumorpha), subg.Euoxytropis(sect.Orobia) and subg.Phacoxytropis(sect.Protoxytropis, sect.Janthinaand sect.Mesogaea) from Turkey were examined using light and scanning electron microscopy to evaluate the taxonomic relevance of macro- and micro-morphological seed characters. As a result of the study, species-specific characters have been determined. Seeds exhibit variation in size, shape, surface sculpturing pattern, hilum position and weight. Seeds ranged from 1.61 to 4.04 mm in length and from 1.02 to 2.56 mm in width. Five different seed shapes were recognised, as prolonged semielliptic, reniform, prolonged reniform, quadratic and cardiform, with a length to width ratio ranging from 1.02 ± 0.08 to 1.75 ± 0.27. Rugulate, rugulate–reticulate and lophate sculpturing patterns were observed in the studied species. According to the results, seed characters, such as the size (length, width and the length/width ratio), the shape, the surface sculpturing and the weight appear to have low taxonomic value in distinguishing subgenera, sections and species. [ABSTRACT FROM PUBLISHER]

Plants grown in urban areas are likely to be exposed to heavy metals from industrial activities and traffic. In particular, Seoul, the capital city of Korea, is affected by seasonal winds from northwest China, named the Asian dust wind, which contains various heavy metals and probably causes heavy metal deposition on plants growing in rooftop gardens in Seoul. Growing media and plants from 18 rooftop gardens distributed throughout Seoul were examined in this study to determine the magnitude of heavy metal (cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb) and zinc (Zn)) exposure in the urban agricultural environment. The heavy metal levels in all of the growing media examined were below the Korean standard limits of soil, although the Cu and Zn levels were elevated due to excessive use of livestock-based composts. Heavy metal concentrations in plants were also comparable with the natural levels. Compared to unwashed plants, washing reduces the hazard quotient of heavy metals by 17–28%. This was due to deposition of airborne dust on the plant surface. Cu, Pb and Zn deposited on the plant surface were attributed to the urban environment such as industrial activities and traffic, while Cr and Ni were attributed to the Asian dust wind carrying the corresponding heavy metals from China to the northwest of Seoul. [ABSTRACT FROM PUBLISHER]

Two hydrophobic cations based on poly-N-ethyl-vinylpyridine were used to produce biologically active complexes. The complexes obtained from tobacco mosaic virus (TMV) spherical particles (SPs), hydrophobic polycation, and a model protein were stable and did not aggregate in solution, particularly at high ionic strengths. The nucleic acid-free SPs were generated by thermal remodeling of the TMV (helical rod-shaped plant virus). The model protein preserved its antigenic activity in the ternary complex (SP–polycation–protein). Immobilization of proteins on the surface of SPs coated with hydrophobic cation is a promising approach to designing biologically active complexes used in bionanotechnologies. [ABSTRACT FROM AUTHOR]

Plant surfaces are colonised by an array of microbes. These microbes have been implicated in protecting plants against invading pathogens. Studies have demonstrated that metabolites of phylloplane microfungi can induce defence responses in their host plants. This investigation relates to formulation of a biocide from metabolites ofAspergillus niger,Trichoderma viride,Alternaria alternataandChaetomium globossum, which are common phylloplane colonisers of tropical plants. The biocide was found to reduce disease incidence through induction of alterations in defence physiology of crop plants. [ABSTRACT FROM AUTHOR]

soil-based root applications and attenuated bacterial strains were evaluated as means to enhance bacteriophage persistence on plants for bacterial disease control. In addition, the systemic nature of phage applied to tomato roots was also evaluated. several experiments were conducted applying either single phages or phage mixtures specific for Ralstonia solanacearum, Xanthomonas perforans or X. euvesicatoria to soil surrounding tomato plants and measuring the persistence and translocation of the phages over time. In general, all phages persisted in the roots of treated plants and were detected in stems and leaves; although phage level varied and persistence in stems and leaves was at a much lower level compared with persistence in roots. Bacterial wilt control was typically best if the phage or phage mixtures were applied to the soil surrounding tomatoes at the time of inoculation, less effective if applied 3 days before inoculation, and ineffective if applied 3 days after inoculation. The use of an attenuated X. perforans strain was also evaluated to improve the persistence of phage populations on tomato leaf surfaces. In greenhouse and field experiments, foliar applications of an attenuated mutant X. perforans 91-118:ΔOPGH strain prior to phage applications significantly improved phage persistence on tomato foliage compared with untreated tomato foliage. Both the soil-based bacteriophage delivery and the use of attenuated bacterial strains improved bacteriophage persistence on respective root and foliar tissues, with evidence of translocation with soil-based bacteriophage applications. Both strategies could lead to improved control of bacterial pathogens on plants. [ABSTRACT FROM AUTHOR]

Within alpine environments the interactions of air temperature, solar irradiance, wind, surface albedo, microtopography, and biotic traits all influence patterns of soil and plant canopy temperatures. The resulting mosaic of surface temperatures has a profound impact on ecosystem processes, plant survival, and ecophysiological performance. Previous studies have documented large and persistent variations in microhabitat temperatures over mesoscale alpine terrains. We have used a novel mobile system to examine changes in soil and plant canopy surface temperatures at spatial scales of centimeters and temporal scales of minutes in an alpine fellfield habitat in the White Mountains of California. In the middle of a summer day, the mean surface temperature differences between points 2, 5, and 10 cm apart were 2.9, 5.4, and 9.0 °C, respectively, and extreme differences of 18 °C or more were found over distances of a few centimeters. These thermal patterns are due not only to substrate material but also to biotic conditions of plant canopy architecture and ecophysiological traits of individual species. The magnitude of temperature variation at these fine scales is greater than the range of warming scenarios in Intergovernmental Panel on Climate Change (IPCC) projections, suggesting that these habitats offer the capacity of significant thermal heterogeneity for plant survival. [ABSTRACT FROM AUTHOR]

ABSTRACT. The aim of this study was to analyse wind, temperature and humidity profiles, surface radiation temperature, and eddy correlation fluxes of momentum and heat over a grass field in order to obtain a better parameterisation of exchange processes over such a surface. The study was performed under summer conditions over a formerly cultivated, uniform and well-watered field of tall grass in central Sweden. An unusually low displacement height, d, was found, at 0.25 times the maximum canopy height h. The roughness length for wind speed could be approximated with the relation z[sub ou] = 0.15(h-d). The relations of d and z[sub ou] would be closer to the traditional ones if a mean canopy height, which is about half of the height used here, had been used in the analysis. The estimation of the quantity kb[sup -1] required accurate determination of the surface temperature. The radiometric surface temperature was measured by two different radiometers, one collecting thermal radiation at angles 0-45 degrees and measuring effectively at 30 degrees from nadir, and the other having a field of view of 15 degrees and being tilted at 45 degrees from nadir. The detected directional variations in the surface radiation temperature were within +/- 1K, and the former radiometer, which was judged to be more accurate, was used for further analysis. The quantity kb[sup -1] was expressed through the roughness-sublayer Stanton number and drag coefficient. Methodologically, the most accurate determination of the Stanton number was to plot the air-surface temperature difference versus the temperature scale multiplied by any other relevant parameter. The quantity kb[sup -1] showed a dependence on the roughness Reynolds number, Re[sub o], and it took the form kB[sup -1] = 0.08 Reo[sup 0.5]-1.9; its value varied between 0 and 4 for the present range of Reo. These results are judged to be in good agreement with theory, considering the complexity of natural surfaces and the simplific... [ABSTRACT FROM AUTHOR]