Foliar Surface Research Articles

On the sustainability of land applications of sewage sludge: How to apply the sewage biosolid in order to improve soil fertility and increase crop yield?

The fertilization using sewage sludge (SS) and/or SS-derived products have been extensively studied and known to increase crop yield as soil nutrients and plant growth are improved. This study aimed to evaluate two SS application methods (i.e. mulching and mixing with the soil) on soil fertility parameters and the productivity of cereal crops. It compared the effect of SS fertilization methods on changes in soil physicochemical parameters in order to highlight the application mode which gives the best agronomic values and sustains soil productivity. Foliar surface, grain starch content and grain yield of durum wheat (Triticum durum) were determined in plants grown in plastic planters for different fertilization treatments (SS-mulched, SS-mixed, urea, and unfertilized). Each SS treatment was applied in three levels (SS1 = 1% w/w ratio, SS2 = 4%, SS3 = 8.3%). The application of SS improved all soil properties compared to the control and urea, with the SS mulching treatment was the best. The significant improvement of soil fertility was confirmed by soil C:P ratio which indicated a good soil mineralization status, in particular under the screen formed by mulching that helped to conserve high soil moisture for optimizing plant growth. Soil calcium accumulated in greater amount in biosolid-soil mixtures than in SS-mulched soils. Regardless of SS doses, the highest crop grain yields were obtained with the SS mulch treatments. Mulching SS, compared to SS-mixed soils, brings better results in terms of improving soil fertility and yielding high productions. The applicable of this method is also easy in the field and/or large-scale cultures.

Adsorption of nanoparticles suspended in a drop on a leaf surface of Perilla frutescens and their infiltration through stomatal pathway

Particulate matter (PM) has become a severe environmental issue, and ultrafine PM particles such as PM2.5 or PM1 can cause various complications and respiratory diseases to human beings. In particular, heavy metals contained in PM particles can contaminate edible plants; for example, plant leaves are exposed to PM particle-laden raindrops. The contaminated edible plants can injure the human health by ingestion, so a detailed understanding on the accumulation of PM particles inside edible plants is essential. In this study, we investigate the infiltration of PM particles in plant tissues with a hypothesis that ultrafine PM particles are absorbed through stomatal pathways. As an edible test plant, Perilla frutescens is selected. Drops of gold nanoparticle (AuNP) suspension are deposited on a leaf of P. frutescens to simulate the scenario where PM particle-laden raindrops fall on patulous stomata of the test plant. To examine AuNP adsorption on the P. frutescens foliar surface and diffusional AuNP absorption through stomatal apertures, we investigate three physical dynamics of AuNPs suspended in a sessile drop: sedimentation, evaporation-driven convective flow, and shrinkage of the drop interface. Quantitative information on the 3D spatial distribution of AuNPs in plant tissues was measured by X-ray imaging and two-photon excitation microscopy.

Foliar surfaces as dust and aerosol pollution monitors: An assessment by a mining site

Recent studies in the southwestern United States have shown that smelting processes and mine tailings emit heavy metal(loid)s that are distributed via wind dispersion to nearby communities. With increased attention regarding the effect of air pollution on environmental health, communities have begun to use citizen/community-based monitoring techniques to measure the concentration of metal(loid)s and evaluate their air quality. This study was conducted in a mining community to assess the efficacy of foliar surfaces as compared to an inverted disc (frisbee) to sample aerosol pollutants in ambient air. The assessment was conducted by evaluating As, Pb, Cd, Cu, Al, Ni, and Zn concentrations versus distance from a former smelter, statistical and regression analyses, and enrichment factor calculations compared to similar sites worldwide. Both the foliar and frisbee collection methods had a decrease in metal(loid)s concentration as a function of distance from the retired smelter. Statistical calculations show that the collection methods had similar mean concentrations for all of the metal(loid)s of interest; however, the tests also indicate that the frisbee collection method generally collected more dust than the foliar method. The enrichment factors from both collection methods were comparable to similar studies by other mining areas referenced, except for aluminum. Since there is evidence of enrichment, correlation between methods, and citizen/community science potential, these efforts show promise for the field. Further studies should consider alternating the types of plant used for foliar collection as well as collecting samples on a more frequent basis in order to sufficiently categorize results based on meteorological conditions.

Comparative morpho-anatomical characteristics and phytochemical constituents of Aloe vera Barbadensis miller and Aloe vera var. Chinensis (haw) Berger

This study was set to investigate the comparative morphological and anatomical characteristics of Aloe vera barbadensis Miller and Aloe vera var. chinensis(Haw) Berger. These are evergreen perennials belonging to Asphodelaceae Juss. in the Order Asparagales Link. The former measures up to 80±20cm in height with lanceolate leaves and rosette habit. The leaves have spiny margins decorated with whitish spots on both foliar surfaces which disappear at maturity. The tubular flowers are orange and densely clustered at the stem apex; corolla is yellowish, tubular and up to 2.5±0.5cm in length whereas the latter is 40±10cm in height with rather lightly green rosette leaves and foliar white spots on foliar surfaces maintained at maturity. The two plants are fleshy and succulent with mild bitter taste. Leaves are amphistomatic with tetracytic sunken stomata. The cells of the epidermal layer are nucleated mostly hexagonal and includepentagonal, heptagonal to square or rounded. Stomatal indices for Aloe vera barbadensis adaxial foliar layer is 7.92 % and abaxial 4.76% while Aloe vera var. chinensis adaxial surface is 7.92% and abaxial 3.85%, not significant. Anatomical studies revealed the cell types from the epidermis, hypodermis, general cortex to the pith are similar in mid-ribs, petioles, stems and nodes. The roots have piths and vasculation is closed type. Phytochemical studies showed the presence of Alkaloids, flavonoids, saponins and tannins in both species, whereas combined anthraquinone was observed absent in both plants. Cardenolide, phlobatannins and free anthraquinones were present in Aloe vera var. chinesis but absent in Aloe vera barbadensis while cyanogenic glycoside was absent in Aloe vera var chinensis but present in Aloe vera barbadensis. The species are used in natural medicine. The information contained in this research would further aid in the taxonomic delimitations of these plants.
 Keywords: Comparative, Aloe vera, phytochemistry, morphology, anatomy, Asphodelaceae.

Similar effects as shade tolerance induced by dust accumulation and size penetration of particulates on cotton leaves

BackgroundDust accumulation covers the leaf’s surface and influences foliar physiological activity. Two independent experiments were carried out to instigate the foliar responses to dust accumulation and the penetration limitation of small dust particles (< 1 μm) on the foliar surface, respectively. In experiment I, three dust accumulation intensities were achieved by a dust spraying treatment. Photosynthesis CO2 exchange and fast chlorophyll fluorescence transient were measured, as well as chlorophyll contents and leaf thickness. In experiment II, the penetration limits of small particulates on the leaf surface were examined by feeding nano-fluorescent microspheres.ResultsDust accumulation alleviated the photoinhibition of Photosystem II and decreased photosynthesis, as represented by net photosynthetic rates (PN) and stomatal conductance to water vapor (gs). Photosynthetic response curves between net photosynthetic rate (PN) and photosynthetically active radiation (PAR) showed that heavy dust accumulation (34.98 ± 2.6 mg cm− 2) increased the light compensation point (LCP) and light saturation point (LSP) and decreased photosynthesis rates under saturating light (PNmax). Leaves became thin due to the lack of a palisade layer while chlorophyll content increased under dust accumulation. Confocal laser scanning microscopy (CLSM) images showed that the larger particles (1 μm) distributed in the regions below the stomata and the smaller ones (0.1 μm) were detected in the wider areas below stomata.ConclusionsThese results suggested that dust accumulation induced similar effects as shade tolerance in cotton leaves but did not trigger more photochemical acclimation to low light. Dust particles (< 1 μm) penetrated leaf surface through stomata.

A new species of Microlicia (Melastomataceae) endemic to restingas in Bahia, Brazil

Microlicia goldenbergii is proposed as a new species from restingas of Canavieiras municipality, Bahia, Brazil. It can be recognized by a combination of ovate leaves with margins and apices that are conspicuously revolute, rectangular petioles 0.1–0.2 mm long, adaxial foliar surfaces that are smooth and glabrous to sparsely glandular-punctate, hypanthia densely glandular-punctate and covered with a few scattered eglandular trichomes 0.3–0.7 mm long that are concentrated only at the torus, dimorphic stamens with polysporangiate anthers and 3–4-locular ovaries. We provide line drawings, photographs, comments on the distribution M. goldenbergii and four putative relatives (M. restingae, M. subsetosa, M. confertiflora and M. cordata), and a distributional map.

Soil texture and watering impact on pot recovery of soil-stripped oil palm (Elaeis guineensis Jacq.) seedlings

The transportation load of oil palm (Elaeis guineensis Jacq.) seedlings from the nursery to planting sites is a crucial problem facing the extension of smallholder plantations in Cameroon. This load can be considerably reduced by removing soil from the roots, which in turn exposes the plants to water and nutrients stresses. A greenhouse pot experiment was carried out to evaluate the recovery performance of such soil-stripped seedlings as a function of watering frequency and soil texture. Plant recovery potential was monitored on 360 nursery seedlings aged 4 months, under two soil types (sandy clay soil with 46% fine particles and sandy loam soil with 19% fine particles) and two watering frequencies (daily and two-days). Three monthly measurements were taken on morphological plant growth parameters including Plant height, Foliar surface, Collar diameter, Root length and Plant weight. Within and between groups analyses of variance and means separation showed the greatest variability for collar diameter, foliar surface and plant weight. All the parameters showed a greater variability and an almost-constant growth from one month to another, except for plant weight that did show a highly significant (p = 0.000) increase between the first measurement and the second. Soil type, watering and their interaction explained 97–99.5% of the variations of all parameters. Except for root length, all other parameters were more sensitive to the effect of soil texture, explaining 83–95% of the total variation. Only plant weight and root length showed slightly greater values under daily watering, other parameters did not show any sensibility to the two watering frequencies proposed in this experiment. Our results showed a low response of plant growth recovery on the low clay sandy loam soil, revealing that a careful selection of a soil texture is crucial for the survival of seedlings and further establishment of the plants following drought stress. It is therefore strongly recommended to many tropical countries where oil palm is an economically important crop, to take this into account during the selection of soil type for oil palm seedlings nursery.

Coronatine Enhances Stalk Bending Resistance of Maize, Thickens the Cell Wall and decreases the Area of the Vascular Bundles

Coronatine (COR) is a phytotoxin produced by the pathogen Pseudomonas syringae, it has a structure similar to that of jasmonates (JAs), but it is much more active as a plant growth regulator. The goal of this study was to gain more insight into the effect and the mechanism of COR effects on stalk characteristics are related lodging resistance of maize. The agronomic traits, stalk ultrastructure, and endogenous hormones in maize stalks were studied in field trails and greenhouses, using hybrid cultivar “Xianyu 335” (XY335), “Zhengdan 958” (ZD958) and inbred line B73 as materials in 2018 and 2019. Different concentration of COR were sprayed onto maize foliar surfaces at the seven-expanded-leaves (V7) stage. Foliar application with 10 µmol L−1 of COR at the V7 stage decreased plant and ear height, increased weight and diameter of the basal internodes, and increased penetration strength and stalk bending resistance. Compared to the control treatment, in COR-treated plants, salicylic acid (SA) and jasmonic acid (JA) were decreased significantly in stalks. The treatment of 10 µmol L−1 of COR enhanced lignin accumulation, the integrity, and the thickness of cell walls in maize stalks in the early stages of stem growth in the inbred line B73, as revealed by autofluorescence microscopy and scanning electron micrographs. Our results indicated that COR improved stalk bending resistance of maize not only by optimizing stalk morphological characteristics, but also by altering hormone levels, which may led to greater lignin accumulation, thickens cell wall, and decreased the area of vascular bundles.

Influence of Surface Structure, Pigmentation and Particulate Matter on Plant Reflectance and Fluorescence.

Optical properties of plant leaves are relevant to evaluate their physiological state and stress effect. The main objective of this work was to study how variegation, pigment composition or reflective features modifies leaves' photophysical behavior. For this purpose, green leaves (Ficus benjamina), purple leaves (Tradescantia pallida), green leaves covered by white trichomes (Cineraria maritima) and variegated leaves (Codiaeum aucubifolium) were analyzed. Firstly, foliar surface morphology was evaluated by scanning electron microscopy. UV-vis and near-IR reflectance and transmittance spectra were obtained to calculate absorption (k) and scattering (s) coefficients. The theoretical approaches of Pile of Plates and Kubelka-Munk's theory resulted still valid for nonstandard leaves with differing surface conditions. However, frequently used spectral indices were not reliable for predicting water content, when leaves differed from conventional ones. The proportionality between the absorption factor and chromophore/pigment concentration was also lost for hairy leaves. A simplified model to describe these facts was presented here. Fluorescence spectra were recorded and corrected, due to light re-absorption. Water-optical parameter connection and pigment-optical parameter connection were thoroughly discussed. Leaf surface morphology and pigmentation have not only influenced the optical features of leaves but also played a role in the effect that particulate matter could cause on leaf photosynthesis.

Identifying the pathways for foliar water uptake in beech (Fagus sylvatica L.): a major role for trichomes.

Foliar water uptake (FWU), the direct uptake of water into leaves, is a global phenomenon, having been observed in an increasing number of plant species. Despite the growing recognition of its functional relevance, our understanding of how FWU occurs and which foliar surface structures are implicated, is limited. In the present study, fluorescent and ionic tracers, as well as microcomputed tomography, were used to assess potential pathways for water entry in leaves of beech, a widely distributed tree species from European temperate regions. Although none of the tracers entered the leaf through the stomatal pores, small amounts of silver precipitation were observed in some epidermal cells, indicating moderate cuticular uptake. Trichomes, however, were shown to absorb and redistribute considerable amounts of ionic and fluorescent tracers. Moreover, microcomputed tomography indicated that 72% of empty trichomes refilled during leaf surface wetting and microscopic investigations revealed that trichomes do not have a cuticle but are covered with a pectin-rich cell wall layer. Taken together, our findings demonstrate that foliar trichomes, which exhibit strong hygroscopic properties as a result of their structural and chemical design, constitute a major FWU pathway in beech.

Heavy metal capture from the suspended particulate matter by Morus alba and evidence of foliar uptake and translocation of PM associated zinc using radiotracer (65Zn)

In urban set up, increasing combustion and processing activities have contaminated the air with toxic heavy metals which are generally enriched on atmospheric particulate matter. Vegetation around urban area act as a sink where such metal enriched particles generally deposit on the foliar surfaces, however, role of vegetation in uptake of metals adhered on the atmospheric particulate matter is yet not explored properly and is important to study to evaluate their role as bio-remediator. The undertaken work examines the foliar surface of Morus alba for its potential to deposit and accumulate atmospheric heavy metals. Further, to understand foliar uptake mechanism and translocation of atmospheric metal enriched on particulate matter a simulated experiment was conducted by labeling the known particle size (45 μm and 120 μm) with radio labeled 65Zn, applied on the tagged leaf with two particle loads, 25 mg and 50 mg. The study showed that owing to its rough foliar surface with trichomes and grooves, Morus alba efficiently trap heavy metal enriched particles and was capable of accumulating metals from particulate matter into different plant parts. It was recorded that 65Zn adhered on different size particles was taken up by tagged leaf of mulberry and majorly translocated to the lower stem and roots. It was also inferred from the study that both particle size and particle load significantly affect the foliar uptake and translocation of atmospheric heavy metal. The study focuses on the fact that urban avenue trees are capable of taking up atmospheric heavy metals and can play a crucial role in improving air quality.

Experimental assessment of the daily exchange of atmospheric mercury in Epipremnum aureum

Mercury (Hg) exchange at the plant leaf-atmosphere interface is an important issue when considering vegetation as a sink or source of this global pollutant. The aim of the study described here was to clarify this process by studying Hg exchange under laboratory conditions with a plant model, namely Epipremnum aureum. The desorption and absorption processes were studied under similar conditions in natural daylight. Hg exchange was measured at the foliar surface, and micrometeorological parameters and stomatal conductance were assessed. The results of the Hg exchange study showed different rhythms for the two processes, i.e. desorption (14-196ngm-2day-1) was slower than absorption (170-1341ngm-2day-1). The daily cycle was more complex in the desorption process, with a maximum when stomatal conductance was high but also with high values during nocturnal hours and a trend to absorption in the mornings. The daily absorption cycles were relatively simple, with values that coincided with positive stomatal conductance values and null values during nocturnal hours. The main factors involved in desorption were stomatal conductance and temperature, but other factors may need to be considered. The absorption process only involved total gaseous Hg, stomatal conductance and relative humidity. A net balance of the two experiments provided data on the amount of Hg transferred per unit leaf area (167ngm-2 for desorption and 9213ngm-2 for absorption), which implies total amounts of 23ng of Hg desorbed and 1280ng absorbed during the whole experiment. Finally, the reversible/non-reversible nature of the Hg exchange process must be reconsidered bearing in mind that Hg within the leaf can be emitted if changes in ambient conditions are appropriate to favour this process.

Distribution of aluminium in hydrated leaves of tea (Camellia sinensis) using synchrotron- and laboratory-based X-ray fluorescence microscopy.

Aluminium (Al) is highly toxic to plant growth, with soluble concentrations being elevated in the ∼40% of arable soils worldwide that are acidic. Determining the distribution of Al in plant tissues is important for understanding the mechanisms by which it is toxic and how some plants tolerate high concentrations. Synchrotron- and laboratory-based X-ray fluorescence microscopy (XFM) is a powerful technique to quantitatively analyse the distribution of elements, including in hydrated and living plants. However, analysis of light elements (z < phosphorus) is extremely challenging due to signal losses in air, and the unsuitability of vacuum environments for (fresh) hydrated plant tissues. This study uses XFM in a helium environment to avoid Al signal loss to reveal the distribution of Al in hydrated plant tissues of Tea (Camellia sinensis). The results show that Al occurs in localised areas across the foliar surface, whereas in cross-sections Al is almost exclusively concentrated in the apoplastic space above and in between adaxial epidermal cells. This distribution of Al is related to the Al tolerance of this species, and accumulation of phytotoxic elements in the apoplastic space, away from sensitive processes such as photosynthesis in the palisade mesophyll cells, is a common tolerance mechanism reported in many different plant species. This study develops an XFM method on both synchrotron and laboratory sources that overcomes the drawbacks of existing analytical techniques, permitting measurement of light elements down to Al in (fresh) hydrated plant tissues.

Leaf dust accumulation and its heavy metal status in selected plant species growing alongside the road in sub-temperate condition of Himachal Pradesh during different season

This study reports dust fall deposition on foliar surfaces of plant species i.e., Toona ciliata, Ficus palmata and Grewia optiva. In relation with its impact on biochemical constituents and surfaces morphology of the foliar. Order of selected plant species according to the dust accumulation was Toona ciliata (31.17 mg m-2) > Ficus palmata (19.00 mg m-2) > Grewia optiva (11.50 mg m-2). The concentration of heavy metals namely cadmium, copper, iron, lead and zinc in the leaf dust was in the range of 0.015 to 0.016, 0.018 to 0.023, 8.747 to 10.093, 0.031 to 0.035 and 0.780 to 0.862 mg g-1, respectively. The heavy metals content decreased with increasing distance from the edge of the selected state highways. The leaf dust contained higher concentration of all the heavy metals during post monsoon as compared to the pre monsoon months. However, Toona ciliata have shown its adaptability to the stress caused by the pollution.

Differences in submillimetre surface morphology and canopy interception storage capacities of Gleditsia triacanthos L. (honeylocust) in relation to canopy phenophase and position

AbstractThe purpose of this study is to examine submillimetre surface morphology and interception storage capacity of foliar surfaces for Gleditsia triacanthos L. (honeylocust) in relation to canopy phenophase (emergence, full leaf, and senescence) and bark surfaces with respect to canopy position through the integration of bioimaging microscopy techniques, three‐dimensional (3D) surface mapping, and laboratory‐based storage capacity analyses. The results demonstrate that there were some statistically significant differences in foliar microrelief and storage capacity across canopy phenophases. Mean foliar roughness and storage capacity peaked during the full leaf phenophase at 173 μm and 0.019 ml cm−2, respectively. Both foliar microrelief and storage capacity were least during emergence. The decreased surface roughness during senescence as compared with full leaf might be due to the tree's inability to repair environmentally induced degradation of the morphological microstructures and epicuticular wax during that phase. Bark microrelief and storage capacity both varied as a function of tree height, with the greatest mean roughness (859 μm) and storage capacity (0.094 ml cm−2) observed in the lower tree. The observed reduction in bark microrelief and storage capacity with height may be attributable to bark age and thickness. Further research that links the 3D submillimetre morphology of canopy surfaces by identifying specific physical mechanisms and processes that either promote or inhibit water storage on foliar and bark surfaces is needed.

Photosystem II 22kDa protein level - a prerequisite for excess light-inducible memory, cross-tolerance to UV-C and regulation of electrical signalling.

It is well known that PsbS is a key protein for the proper management of excessive energy in plants. Plants without PsbS cannot trigger non-photochemical quenching, which is crucial for optimal photosynthesis under variable conditions. Our studies showed wild-type plants had enhanced tolerance to UV-C-induced cell death (CD) upon induction of light memory by a blue or red light. However, npq4-1 plants, which lack PsbS, as well as plants overexpressing this protein (oePsbS), responded differently. Untreated oePsbS appeared more tolerant to UV-C exposure, whereas npq4-1 was unable to adequately induce cross-tolerance to UV-C. Similarly, light memory induced by episodic blue or red light was differently deregulated in npq-4 and oePsbS, as indicated by transcriptomic analyses, measurements of the trans-thylakoid pH gradient, chlorophyll a fluorescence parameters, and measurements of foliar surface electrical potential. The mechanism of the foliar CD development seemed to be unaffected in the analysed plants and is associated with chloroplast breakdown. Our results suggest a novel, substantial role for PsbS as a regulator of chloroplast retrograde signalling for light memory, light acclimation, CD, and cross-tolerance to UV radiation.

Fertilizer Application in Basil (Ocimum basilicum) Cultivation in Greece

Basil (Ocimum basilicum L.) is cultivated in many countries as an aromatic herb because of its essential oils that have many uses. In our study, nitrogen application at three levels and a tester was used, and effects on quantity and essential oil characteristics were recorded. The purpose was to explore nitrogen effects on essential oil of basil in Greece. Two commercial cultivars of basil were used: Red Rubin and Lettuce Leaf. The experiment conducted was a replicated fully randomized complete block split-split plot with the two varieties as the main factor, split factor was nitrogen levels (four rates) and split in time factor was sampling time (six dates). Nine characteristics were studied (chlorophyll content measurements-CCM, foliar surface, plant height, fresh weight, dry weight, leaves/stems ratio for fresh weight, leaves/stems ratio for dry weight, essential oil content of flowers and essential oil content of leaves). Basil plants were generally favoured by nitrogen application and many characteristics were improved. Especially for foliar surface, chlorophyll content, plant height and biomass weight (for both cultivars). Red Rubin exploited better nitrogen application in comparison to Lettuce leaf, especially for the second level. On the opposite, Lettuce leaf showed better essential oil production. The two cultivars differed also in the composition of essential oils with impact on essential oil properties. Finally, the biological cycle was accelerated for both cultivars because of increased metabolism after nitrogen application. Genotype × environment interaction was present in many cases, except for foliar surface, leaves/stem ratio and essential oil content of leaves.

Soil loss from small rangeland plots under simulated rainfall and run-on conditions

In order to predict and mitigate soil erosion it is necessary to understand the mechanism of detachment by raindrops and by shallow flow. The relative contribution of these drivers to the overall erosion process on arid rangelands is not well understood and field experimental data is limited. The experiment was conducted using simulated rainfall and overland flow on 56 small (2 m × 6 m) natural plots located on 7 rangeland sites in Arizona, USA. The goals of the study were (i) to compare raindrop driven and shallow flow driven erosion rates on arid rangeland, and (ii) assess the role of flow hydraulics, vegetation, and cover on attenuation of erosive impact of raindrops. A total of 520 measurements of steady state flow under two treatments (rainfall and run-on) were obtained. Flow discharge on the plots varied between 3 and 355 mm h−1 and unit sediment yield varied between 0.02 and 30 g m−2 min−1. Sediment yield was best predicted by flow discharge for both rainfall and run-on treatments on all sites explaining 18% to 75% of its variability. There was statistically significant difference between two treatments. Rainfall treatment generated 2 to 44 times more sediment than run-on at the same discharge rate. We found no strong evidence of raindrop impact affecting overland flow velocity. Among 19 variables related to surface conditions a weak correlation was found between sediment yield and plant foliar cover, structure, and surface litter. However, there was no single best cover predictor common for all ecological sites tested.

CHEMICAL CONTROL OF ASIAN SOYBEAN RUST AS A FUNCTION OF CULTIVAR, ROW SPACING AND SPRAY BAR SUPPORT SYSTEMS

Product deposition and foliar surface cover are highly impacting factors on the efficiency of foliar fungicides applied to soybean cultivars, due to their low mobility, with side effects on Asian soybean rust (ASR) control. Spray bar support systems, such as the air curtain (Vortex®) and the use of nozzles along the bar (Dropleg®), stand out as an alternative to obtain a better distribution of fungicide throughout the plant. In this study, two spray bar support systems (Vortex® and Dropleg®) were, therefore, evaluated and compared with the conventional spraying method based on the biological efficacy in ASR control. In order to do this, two harvests, with three spacing between rows and two cultivars were employed. Vortex® and Dropleg® spray bar support mechanisms do not effectively contribute to the optimization of Asian soybean rust control or to the grain crop yield, regardless of cultivar and row spacing. Decreasing the row spacing did not influence the level of control of Asian soybean rust, as the highest grain yield was obtained with the smallest spacing. The cultivar with genetic resistance to Asian rust showed lower levels of this disease, thus, greater control against the use of fungicides.

Effects of Chronic Dust Load On Leaf Pigments of the Landscape Plant Murraya Paniculata

In the past few years, a considerable decrease in growth and development of landscape plants was recorded, possibly due to chronic exposure to toxic pollutants, with dust probably playing a major role. In the current study, Murraya paniculata were grown in a greenhouse for a period of 4 months, during which roadside dust was sprinkled daily on the slightly damp leaves at different concentrations: T0 (0 g/plant-control), T1 (1 g/plant), T2 (3 g/plant) and T3 (5 g/plant). Roadside sediments were collected with a vacuum pump and passed through a filter to obtain a fine particle size (less than 800 μm). Phenotypic studies of leaves revealed that continuous addition of undesired dust effluents affects the foliar surface of the leaves and changes its morphology. Treatment with dust significantly increased the abscisic acid concentration of leaves and shoots and the effects were more severe in high level of dust treatments. Compared to control, chlorophyll, porphyrin, chlorophyllide and pheophytin contents were significantly decreased in the dust treated groups. In contrast, carotenoid and polar carotenoid contents were not influenced by dust (p > 0.05), while non-polar carotenoid contents were significantly reduced by different levels of dust treatments. This study concludes that roadside dust depositions have degradative effects on photosynthetic pigments, with extensive effects on growth and development of plants.