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Despite the positive results of using elicitors to induce resistance against plant diseases, some factors have inhibited the popularization of their use in agriculture. There is an energetic cost related to the elicitors' induced response which can cause undesired effects on growth under low-pressure disease conditions. Elicitors can create phytotoxicity and show high variation in their efficiency between different genotypes within the same crop; in addition, the positive results related to the induced resistance may not repeat in field treatments, adding to the possibility that they are not economically viable. Thus, we carried out two experiments to investigate the technical and economic efficiency of acibenzolar-S-methyl (ASM) and its association with fungicides in the control of leaf diseases of susceptible and resistant wheat varieties, and as how it reflects on the photosynthetic and production performance of wheat. This study showed the limitations of incorporating ASM into foliar fungal disease control in economic terms. However, it was evident that ASM effectively induced plant resistance against Leaf Rust and Powdery Mildew in the field and can be considered a sustainable option for wheat cultivation. Even though its association with chemical control was not the best economic strategy the use of ASM is a tool that can be incorporated into wheat cultivation to minimize the emergence of fungicide-resistant pathogens due to the diversification of modes of action employed and reduce the toxic residue deposition to the environment and human health., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Mateus Batista Remor reports supplies was provided by Syngenta Crop Protection. Mateus Batista Remor reports a relationship with Syngenta Crop Protection that includes: employment. The authors declare that Mateus Batista Remor (co-author), a collaborator at Syngenta Crop Protection, made the ASM product available for application in the experiments and participated in the conceptualization, definition of methodology and conduct of one of the experiments., (© 2023 The Authors.)

Witches' broom disease of cacao is caused by the pathogenic fungus Moniliophthora perniciosa. By using tomato (Solanum lycopersicum) cultivar Micro-Tom (MT) as a model system, we investigated the physiological and metabolic consequences of M. perniciosa infection to determine whether symptoms result from sink establishment during infection. Infection of MT by M. perniciosa caused reductions in root biomass and fruit yield, a decrease in leaf gas exchange, and down-regulation of photosynthesis-related genes. The total leaf area and water potential decreased, while ABA levels, water conductance/conductivity, and ABA-related gene expression increased. Genes related to sugar metabolism and those involved in secondary cell wall deposition were up-regulated upon infection, and the concentrations of sugars, fumarate, and amino acids increased. 14C-glucose was mobilized towards infected MT stems, but not in inoculated stems of the MT line overexpressing CYTOKININ OXIDASE-2 (35S::AtCKX2), suggesting a role for cytokinin in establishing a sugar sink. The up-regulation of genes involved in cell wall deposition and phenylpropanoid metabolism in infected MT, but not in 35S::AtCKX2 plants, suggests establishment of a cytokinin-mediated sink that promotes tissue overgrowth with an increase in lignin. Possibly, M. perniciosa could benefit from the accumulation of secondary cell walls during its saprotrophic phase of infection., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

We present a detailed protocol for measuring extracellular electrical signals in plants using the electrode insertion technique. Using this approach, it is possible to measure long-distance electrical signaling induced by several stimuli, including wounding, current application, irrigation, burning, and others. Additionally, we describe how to associate gas exchange measurements using an infra-red gas analyzer (IRGA, Model Li-6400, Li-Cor) and turgor pressure measurements using a patch clamp pressure probe (ZIM-probe, YARA ZIM-plant Technology) to measure extracellular electrical signals. • The method requires a complete electrical circuit that includes a measuring device (amplifier and voltmeter) and electrodes that provide a contact between the biological material and the equipment. • The infra-red gas analyzer (IRGA), needs to be grounded because it is an important source of noise for electrophysiological measurements. • The ZIM-probe did not cause any interference in electrical signal measure. • Our approach is useful for plant physiologists wishing to implement the technique of measuring electrical signals in plants, in association with other parameters of plant physiology. In addition, our text was written for agricultural and biological scientists who are not electronics specialists., (© 2021 Published by Elsevier B.V.)

Jellyfish stinging capsules known as nematocysts are explosive, natural-injection systems with high potential as a natural drug-delivery system. These organelles consist of a capsule containing a highly folded thin needle-like tubule and a matrix highly concentrated with charged constituents that enable the tubule to fire and penetrate a target. For the purpose of using these nematocysts as drug delivery system it is first required to purify subpopulations from heterogeneous population of capsules and to investigate each subpopulation's distinct function and characteristics. Here, the nematocysts' dielectric properties were experimentally investigated using dielectrophoretic and electrorotational spectra with best fits derived from theoretical models. The dielectric characterization adds to our understanding of the nematocysts' structure and function and is necessary for the dielectrophoretic isolation and manipulation of populations. As expected, the effect of monovalent and divalent exchange cations resulted in higher inner conductivity for the NaCl treated capsules; this result stands in agreement with their relative higher osmotic pressure. In addition, an efficient dielectrophoretic isolation of different nematocyst subpopulations was demonstrated, paving the way to an understanding of nematocysts' functional diversity and the development of an efficient drug delivery platform., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Most seabird species nest colonially on cliffs or islands with limited terrestrial predation, so that oceanic effects on the quality or quantity of prey fed to chicks more often determine nest success. However, when predator access increases, impacts can be dramatic, especially when exposure to predators is extended due to slow growth from inadequate food. Kittlitz's Murrelet (Brachyramphus brevirostris), a rare seabird having experienced serious declines, nests solitarily on the ground in barren, often alpine areas where exposure to predators is generally low. Nestling growth rates are exceptionally high and nestling periods very short relative to other Alcidae. This strategy reduces duration of exposure to predators, but demands adequate deliveries of high‐energy prey. In an area where foxes can access nests, we investigated whether varying energy content of prey fed to chicks could alter growth rates and resulting duration of predator exposure, and whether prolonged exposure appreciably reduced nest success. From 2009 to 2016, we monitored 139 nests; 49% were depredated (almost all by foxes) and 25% fledged. Prey fed to nestlings were 80% Pacific sand lance (Ammodytes personatus) and 19% capelin (Mallotus villosus), with capelin having 2.3× higher energy content per fish. In a year of slow chick growth, increased sand lance energy density of 31% (4.29–5.64 kJ/g, within published values), or increased proportion of capelin in the diet from 5.6% to 27.2%, would have allowed maximum chick growth. Maximum growth rates were attainable by delivering only 1.9 capelin/d versus 5.5 sand lance/d. Slow growth increased time to fledging by up to 5 d, decreasing survival by 7.7% (0.142–0.131). Breeding propensity of Kittlitz's Murrelet averages only 20%, so even small changes in nest success could affect populations. Although nest success was limited mainly by predation, oceanic effects on prey quantity and quality had overriding impacts in one year (2015 heat wave), and small but substantive effects in other years by mediating exposure to predation. Climate warming that decreases availability of high‐energy forage fish, or increases expansion of predators into nesting habitats, may disproportionately affect this sensitive species and others with predator‐accessible nests and demands for energy‐rich prey. [ABSTRACT FROM AUTHOR]

The silkworm, Bombyx mori, is reared on a large scale, mainly for silk production. The waste from this silk production, like pupae, is underused. As an edible insect, B. mori is a good source of protein in human food and animal feed. In recent years, European legislation on the use of insects has evolved and a multitude of European companies have initiated the rearing of insects specifically for food and feed applications. Regarding animal feed, Commission Regulations (EU) 2021/1372 and 2021/1925 authorize eight insect species, including silkworm, as processed animal proteins for use in fish, pig, and poultry feed. The incorporation of edible insects into the human diet falls within Regulation (EU) No. 2015/2283 concerning novel foods. Implementation of authentication methods is imperative to ensure the conformity of the products. In the present study, we propose a specific real-time PCR method for the detection of silkworm (B. mori). The developed PCR test amplifies a 98 bp fragment of the cadherin gene. This gene is present in a single-copy per haploid genome, as demonstrated by experimental evidence. The qualitative method was successfully evaluated on the performance criteria of specificity, sensitivity, efficiency, robustness, and transferability. The applicability of the test was assessed on samples of B. mori from industry. Light microscopy and DNA metabarcoding approaches were used as a complement to genomic analysis as a means of providing authentication of the samples. [ABSTRACT FROM AUTHOR]

Background: Plant cells usually sustain a stable membrane potential due to influx and/or efflux of charged ions across plasma membrane. With the growth and development of plants, different tissues and cells undergo systemic or local programmed decline. Whether the membrane potential of plasma membrane could report senescence signal of plant tissues and cells is unclear. Results: We applied a maneuverable transmembrane potential (TMP) detection method with patch-clamp setup to examine the senescence signal of leaf tissue cells in situ over the whole life cycle in Arabidopsis thaliana. The data showed that the TMPs of plant tissues and cells were varied at different growth stages, and the change of TMP was higher at the vegetative growth stage than at the reproductive stage of plant growth. The distinct change of TMP was detectable between the normal and the senescent tissues and cells in several plant species. Moreover, diverse abiotic stimuli, such as heat stress, hyperpolarized the TMP in a short time, followed by depolarized membrane potential with the senescence occurring. We further examined the TMP of plant chloroplasts, which also indicates the senescence signal in organelles. Conclusions: This convenient TMP detection method can report the senescence signal of plant tissues and cells, and can also indicate the potential of plant tolerance to environmental stress. [ABSTRACT FROM AUTHOR]

Previous studies on soil water–plant relations have mostly focused on the soil water content (SWC), while the effect of soil moisture stability on plant growth has received surprisingly little attention. Potted tomato seedlings were used to examine the effect of stable soil moisture (SM) and fluctuating soil moisture (FM) on plant growth, development, and water use efficiency (WUE) in this study. The results showed that (i) soil moisture stability significantly affected the growth and development, photosynthetic characteristics, morphological traits, root morphology, and water physiological characteristics of seedling tomatoes, with SM being more conducive for most of these indices. (ii) SM improved the leaf WUE by reducing the content of abscisic acid in plants, regulating plant osmotic substances, maintaining a high gas exchange rate, and promoting plant morphology. (iii) SM could avoid water stress on tomato seedlings; even if the SWC of SM was equal to or lower than the SWC of FM, water stress would not occur under SM, whereas it would occur under FM. Overall, compared with FM, SM promoted beneficial plant morphology, maintained a high gas exchange rate, and did not induce water stress for tomato seedlings—ultimately improving WUE. This effect was more effective under low-SWC conditions than under high-SWC conditions. These findings provide a new perspective and theoretical basis for soil water–plant relations and indicate that SM has great potential in promoting plant growth and improving WUE. [ABSTRACT FROM AUTHOR]

Electrical signals are generated and transmitted through plants in response to stimuli caused by external environment factors, such as touching, luminosity, and leaf burning. By analyzing a specific plant's electrical responses, it is possible to interpret the impact of external aspects in the plasma membrane potential and, thus, determine the cause of the electrical signal. Moreover, these signals permit the whole plant structure to be informed almost instantaneously. This work presents a brief discussion of plants electrophysiology theory and low-cost signal conditioning circuits, which are necessary for the acquisition of plants' electrical signals. Two signal conditioning circuits, which must be chosen depending on the signal to be measured, are explained in detail and electrical simulation results, performed in OrCAD Capture Software are presented. Furthermore, Monte Carlo simulations were performed to evaluate the impact of components variations on the accuracy and efficiency of the signal conditioning circuits. Those simulations showed that, even after possible component variations, the filters' cut-off frequencies had at most 4% variation from the mean. [ABSTRACT FROM AUTHOR]

Background: Despite the optimal characteristics of peat, more environmental-friendly materials are needed in the nursery sector, although these must guarantee specific quantitative and qualitative commercial standards. In the present study, we evaluated the influence of biochar and compost as peat surrogates on yield and essential oil profile of two different varieties of basil (Ocimum basilicum var. Italiano and Ocimum basilicum var. minimum). In two 50-day pot experiments, we checked the performances of biochar from pruning of urban trees and composted kitchen scraps, both mixed in different proportions with commercial peat (first experiment), and under different nitrogen (N) fertilization regimes (second experiment), in terms of plant growth and volatile compounds profile of basil., Results: Total or high substitution of peat with biochar (100% and 50% v.v.) or compost (100%) resulted in seedling death a few days from transplantation, probably because the pH and electrical conductivity of the growing media were too high. Substrates with lower substitution rates (10-20%) were underperforming in terms of plant growth and color compared to pure commercial peat during the first experiment, whereas better performances were obtained by the nitrogen-fertilized mixed substrates in the second experiment, at least for one variety. We identified a total of 12 and 16 aroma compounds of basil (mainly terpenes) in the two experiments. Partial replacement of peat did not affect basil volatile organic compounds content and composition, whereas N fertilization overall decreased the concentration of these compounds., Conclusion: Our results support a moderate use of charred or composted materials as peat surrogates. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

Copyright of Revista em Agronegócio e Meio Ambiente is the property of Revista em Agronegocio e Meio Ambiente and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plants have developed various mechanisms to respond specifically to each biotrophic attack. It has been shown that the electrical signals emitted by plants are associated with herbivory stress responses and can lead to the activation of multiple defences. Bt cotton is a genetically modified pest-resistant plant that produces an insecticide from Bacillus thuringiensis (Bt) to control Lepidopteran species. Surprisingly, there is no study–yet, that characterizes the signalling mechanisms in transgenic cotton plants attacked by non-target insects, such as aphids. In this study, we characterized the production of electrical signals on Bt and non-Bt cotton plants infested with Aphis gossypii and, in addition, we characterized the dispersal behaviour of aphids to correlate this behaviour to plant signalling responses. Electrical signalling of the plants was recorded with an extracellular measurement technique. Impressively, our results showed that both Bt and non-Bt cotton varieties, when attacked by A. gossypii, emitted potential variation-type electrical signals and clearly showed the presence of distinct responses regarding their perception and the behaviour of aphids, with evidence of delay, in terms of signal amount, and almost twice the amount of Cry1F protein was observed on Bt cotton plants at the highest density of insects/plant. We present in our article some hypotheses that are based on plant physiology and insect behaviour to explain the responses found on Bt cotton plants under aphid stress. [ABSTRACT FROM AUTHOR]

Copyright of Anales de Biología is the property of Servicio de Publicaciones de la Universidad de Murcia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Most seabird species nest colonially on cliffs or islands with limited terrestrial predation, so that oceanic effects on the quality or quantity of prey fed to chicks more often determine nest success. However, when predator access increases, impacts can be dramatic, especially when exposure to predators is extended due to slow growth from inadequate food. Kittlitz’s Murrelet (Brachyramphus brevirostris), a rare seabird having experienced serious declines, nests solitarily on the ground in barren, often alpine areas where exposure to predators is generally low. Nestling growth rates are exceptionally high and nestling periods very short relative to other Alcidae. This strategy reduces duration of exposure to predators, but demands adequate deliveries of high‐energy prey. In an area where foxes can access nests, we investigated whether varying energy content of prey fed to chicks could alter growth rates and resulting duration of predator exposure, and whether prolonged exposure appreciably reduced nest success. From 2009 to 2016, we monitored 139 nests; 49% were depredated (almost all by foxes) and 25% fledged. Prey fed to nestlings were 80% Pacific sand lance (Ammodytes personatus) and 19% capelin (Mallotus villosus), with capelin having 2.3× higher energy content per fish. In a year of slow chick growth, increased sand lance energy density of 31% (4.29–5.64 kJ/g, within published values), or increased proportion of capelin in the diet from 5.6% to 27.2%, would have allowed maximum chick growth. Maximum growth rates were attainable by delivering only 1.9 capelin/d versus 5.5 sand lance/d. Slow growth increased time to fledging by up to 5 d, decreasing survival by 7.7% (0.142–0.131). Breeding propensity of Kittlitz’s Murrelet averages only 20%, so even small changes in nest success could affect populations. Although nest success was limited mainly by predation, oceanic effects on prey quantity and quality had overriding impacts in one year (2015 heat wave), and small but substantive effects in other years by mediating exposure to predation. Climate warming that decreases availability of high‐energy forage fish, or increases expansion of predators into nesting habitats, may disproportionately affect this sensitive species and others with predator‐accessible nests and demands for energy‐rich prey.

Plants have organic components produced as secondary metabolites able to positively or negatively interfere on normal development of other species. The objective of this research was to determine the phytotoxic effects of aqueous leaf extract from two species Rubiaceae family: Tocoyena formosa and Rudgea viburnoides on the germination and initial development of lettuce (Lactuca sativa L). The extract was obtained from mixing 50 g of fresh leaf and 500 mL of distilled water. The experiment was arranged in completely randomized design for each specie, subjected to five extract concentrations: 0, 25, 50, 75 and 100%; and 4 repetitions of 50 seed each. The bioassays were performed in laboratory at controlled temperature and luminosity during seven days. Results showed that the aqueous extract of both species do not affected the germination and the percent of abnormal lettuce seedlings. R. viburnoides showed no pronounced difference in relation to shoot length and dry biomass; however, the root length was reduced by 85%. The extract of T. formosa at higher concentrations, drastically reduce the dry biomass and length of shoots and roots. Therefore, both species have phytotoxic effect on seedling growth of lettuce being the length root the most affected variable. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to use a particle velocity measurement technique on a tapered microelectrode device via changes of an applied voltage, which is an enhancement of the electric field density in influencing the dipole moment particles. Polystyrene microbeads (PM) have used to determine the responses of the dielectrophoresis (DEP) voltage based on the particle velocity technique. Design/methodology/approach: Analytical modelling was used to simulate the particles' polarization and their velocity based on the Clausius–Mossotti Factor (CMF) equation. The electric field intensity and DEP forces were simulated through the COMSOL numerical study of the variation of applied voltages such as 5 V p-p, 7 V p-p and 10 V p-p. Experimentally, the particle velocity on a tapered DEP response was quantified via the particle travelling distance over a time interval through a high-speed camera adapted to a high-precision non-contact depth measuring microscope. Findings: The result of the particle velocity was found to increase, and the applied voltage has enhanced the particle trajectory on the tapered microelectrode, which confirmed its dependency on the electric field intensity at the top and bottom edges of the electrode. A higher magnitude of particle levitation was recorded with the highest particle velocity of 11.19 ± 4.43 µm/s at 1 MHz on 10 V p-p, compared to the lowest particle velocity with 0.62 ± 0.11 µm/s at 10 kHz on 7 V p-p. Practical implications: This research can be applied for high throughout sensitivity and selectivity of particle manipulation in isolating and concentrating biological fluid for biomedical implications. Originality/value: The comprehensive manipulation method based on the changes of the electrical potential of the tapered electrode was able to quantify the magnitude of the particle trajectory in accordance with the strong electric field density. [ABSTRACT FROM AUTHOR]

We analyzed the δ13C and δ15N values in the vibrissae of captive adult breeding South American sea lions ( Otaria byronia) fed at a constant diet and then used this information to analyze the change in stable isotope values along the vibrissae from wild individuals. The overall diet-to-vibrissa discrimination factor of the captive animals was 3.0‰ ± 0.1‰ for δ13C and 3.6‰ ± 0.1‰ for δ15N, but the stable isotope ratios fluctuated periodically despite constant diet. The δ13C and δ15N values of the captive male declined at the end of the breeding season, whereas the δ13C values of the female increased during the central part of pregnancy and the δ15N values peaked during lactation. The δ13C and δ15N values of adult wild specimens also fluctuated periodically and vibrissae growth rate (0.15 mm/d in both sexes) was slightly lower than in captivity (0.17 mm/d), assuming an annual periodicity for oscillations. Similarities in the amplitude of the cycles of captive and wild males suggested that fasting was probably the main source of periodic variability in the δ15N of wild males, whereas pregnancy and lactation were probably the main source of periodic variability for the δ13C of wild females. [ABSTRACT FROM AUTHOR]

Capelin occupy a key trophic role and have a broad latitudinal distribution in the northeastern Pacific and Arctic Oceans. Understanding their adaptation to a range of conditions is important to predicting how they will respond to climate change. To quantify the variation in body condition in different physical environments, we measured energy density, RNA/DNA ratios, carbon and nitrogen stable isotope ratios in 62 juvenile capelin along the Western Alaskan coast from Bristol Bay to Point Barrow ranging across approximately 14° of latitude. Energy density correlated positively with latitude, whereas RNA/DNA (instantaneous growth index) was strongly correlated with sea surface temperature, indicating that optimal growth of capelin was achieved at ~9 °C, followed by rapid decreases in RNA/DNA ratios at higher temperatures. δC and δN had strong, inverse nonlinear relationships with latitude. Depletion of δC seen in capelin North of Bristol Bay may be related to the incorporation of allochthonous basal resources into the diets of juvenile capelin from nearby riverine inputs. Observed enrichment of δN North of Bristol Bay is likely to be related to incorporation of higher trophic level prey items. Given inverse relationship between δC and δN, these prey items are likely available due to the increased diversity of basal resources from increased inputs of riverine organic material. [ABSTRACT FROM AUTHOR]

The Barents Sea shelf system, particularly the southwestern, western and southern parts, is one of the most productive ocean regions in the world due to the influence of warm Atlantic water. We conducted an analysis of long-term data based on original and published sources focused on the trends in abundance of key commercial species in the Barents Sea. We specifically examined the patterns and characteristics of both invasive species and invasion processes, using the example of two introduced crabs: the red king crab ( Paralithodes camtschaticus) and the snow crab ( Chionoecetes opilio), which in polar ecosystems may provide an important case study for improving our ability to predict the impact of new invaders. Warm temperature anomalies were observed in the Barents Sea in the 20th century and in the early twenty-first century, with peaks from 2001 to 2007 and in 2012, associated with a pronounced decrease in total ice cover since 1999. Since their introduction, the stock biomass of red king crabs has varied widely. These fluctuations were associated with high levels of illegal fishing of red king crab. The total biomass of commercial snow crabs increased exponentially in the last decade. Since the late 1990s the stock of northern shrimp has varied with an overall rising trend, although landings in more recent years were relatively stable. Cod, haddock, and saithe stocks remained at relatively high levels. Capelin stock size is characterized by large fluctuations that are likely to reflect natural processes. Cross-correlation analysis suggests that neither crab species had negative effects on the stocks of important fish. However, a potential negative impact of snow crab on the northern shrimp population could not be rejected due to their overlapping distribution and predator-prey interactions. The high overall productivity of the Barents Sea in recent years, as evidenced by high abundances of major fish stocks, is more likely associated with warming in the Arctic region, and the introduction of both crab species has had no apparent detrimental effects on fish stocks while resulting in positive economic benefits. [ABSTRACT FROM AUTHOR]

In the Barents Sea, strong top predator responses to repeated stock collapses of the forage fish capelinMallotus villosushave been observed. The white-beaked dolphinLagenorhynchus albirostris, a flexible predator with a diverse diet in other marine systems, has been associated with capelin in the Barents Sea. Yet, their distribution and foraging ecology in this ecosystem remain largely unknown. Here we use synoptically collected dolphin and prey spatial data to investigate the dolphins' distribution and spatial associations with potential prey species, including the spatial responses to a capelin stock collapse of 2003–2006 and recovery in 2007–2009. Since dolphin–prey associations may be scale-dependent, analyses were conducted at two spatial scales: (1) the habitat scale, by investigating spatial associations between species distributions averaged across years, and (2) the mesoscale, by investigating spatial associations within 50 × 50 km grid cells. At the habitat scale, dolphins overlapped with different prey species in different parts of their habitat. At the mesoscale, the dolphins were associated with blue whiting in southern Atlantic waters, while no prey associations were identified in the Polar Front area, where both capelin and gadoids are abundant. The poor dolphin–prey associations in this area could indicate dolphin distributions spatially constrained by physiological limitations, habitat productivity, or niche partitioning. No strong dolphin responses to capelin collapse and recovery were observed, indicating sufficient availability of alternative prey during the collapse. [ABSTRACT FROM PUBLISHER]

The global population is increasing day by day. To meet the food demand for such a huge number of people, crop production must increase without damaging the environment, and to prevent synthetic chemical herbicides from polluting the environment, controlling weeds using bioherbicides is essential. Accordingly, using phytotoxic substances obtained from plants for biological weed management has attracted attention. The plant Albizia richardiana possesses phytotoxic compounds that have been previously recorded. Hence, we have conducted this research to characterize more phytotoxic compounds in Albizia richardiana. Aqueous methanolic extracts of Albizia richardiana plant significantly restricted the growth of the examined plants lettuce and Italian ryegrass in a species- and concentration-dependent manner. Three active phytotoxic compounds were isolated through various chromatographic methods and identified as compound 1, 2, and 3. Compound 3 exhibited stronger phytotoxic potentials than the other two compounds and significantly suppressed the growth of Lepidium sativum (cress). The concentration of the compounds required for 50% growth reduction (I50 value) of the Lepidium sativum seedlings ranged between 0.0827 to 0.4133 mg/mL. The results suggest that these three phytotoxic compounds might contribute to the allelopathic potential of Albizia richardiana. [ABSTRACT FROM AUTHOR]

Simple Summary: Numerous stressors (drought, low and high temperatures, mechanical damages, etc.) act on plants under environmental conditions, suppressing their physiological processes (in particular, photosynthesis). Abscisic acid (ABA) is an important hormone, which participates in increasing plant tolerance to the action of stressors; as a result, treatment by exogenous ABA is a perspective way of regulating the tolerance in agriculture. We investigated the influence of ABA spraying on photosynthetic processes, as well as on their heat tolerance and their regulation by electrical signals propagating after local burning and modifying photosynthesis. It was shown that ABA spraying decreased photosynthetic activity and increased photosynthetic heat tolerance; additionally, the ABA treatment weakened the influence of electrical signals on photosynthesis. We revealed that these responses could be caused by a decrease in activity of H+-ATP-ase, which is an important ion transporter in plant cell plasma membrane that supports efflux of H+ from cytoplasm. As a whole, our results show the potential influence of the ABA treatment on photosynthetic processes, which is related to a decrease in activity of H+-ATP-ase. The result can be potentially useful for development of new methods of management of plant tolerance in agriculture. Abscisic acid (ABA) is an important hormone in plants that participates in their acclimation to the action of stressors. Treatment by exogenous ABA and its synthetic analogs are a potential way of controlling the tolerance of agricultural plants; however, the mechanisms of influence of the ABA treatment on photosynthetic processes require further investigations. The aim of our work was to investigate the participation of inactivation of the plasma membrane H+-ATP-ase on the influence of ABA treatment on photosynthetic processes and their regulation by electrical signals in peas. The ABA treatment of seedlings was performed by spraying them with aqueous solutions (10−5 M). The combination of a Dual-PAM-100 PAM fluorometer and GFS-3000 infrared gas analyzer was used for photosynthetic measurements; the patch clamp system on the basis of a SliceScope Pro 2000 microscope was used for measurements of electrical activity. It was shown that the ABA treatment stimulated the cyclic electron flow around photosystem I and decreased the photosynthetic CO2 assimilation, the amplitude of burning-induced electrical signals (variation potentials), and the magnitude of photosynthetic responses relating to these signals; in contrast, treatment with exogenous ABA increased the heat tolerance of photosynthesis. An investigation of the influence of ABA treatment on the metabolic component of the resting potential showed that this treatment decreased the activity of the H+-ATP-ase in the plasma membrane. Inhibitor analysis using sodium orthovanadate demonstrated that this decrease may be a mechanism of the ABA treatment-induced changes in photosynthetic processes, their heat tolerance, and regulation by electrical signals. [ABSTRACT FROM AUTHOR]

Weed management is an important issue since weeds directly compete with crop plants for space, nutrients; serve as habitat for insect pests and diseases, and can create a significant annual reduction in crop productivity. This study focused on evaluating the contribution of the secondary metabolites of the fruit pulp of Couroupita guianensis Aubl. for its potential growth inhibitory effect. Crude extracts of C. guianensis fruit pulp were collected with different solvents and applied to test plants in petri dishes. The crude extracts of methanol and 1% dimethyl sulfoxide (DMSO) showed potential growth inhibitions with the 50% effective concentration (EC50) of 223 and 229 µg/mL in the bioassay experiment. In the greenhouse pot experiment, soil incorporated with oven-dried fruit pulp of C. guianensis was evaluated on cultivated plant species including Lactuca sativa L., Trifolium repens L., Medicago sativa L., Lolium multiflorum Lam., and Phleum pratense L. The incorporation of dried fruit pulp of C. guianensis into soil reduced shoot and root lengths and the germination percentage of test plants. It was observed that the monocot plants were more affected than the dicot plants. The fruit pulp of C. guianensis was subjected to reversed-phase high-performance liquid chromatography (HPLC) analysis to identify the active compounds. Indigo, identified as one of the candidate compounds of the C. guianensis, had high specific activity (i.e., strong inhibitory activity) in a phytotoxicity bioassay and could explain through the total activity concept the growth inhibitory effect of the C. guianensis on test plants. The results suggested that indigo has plant growth inhibitory effect, indicating the allelopathic potential of C. guianensis, which could be exploited in sustainable weed management. [ABSTRACT FROM AUTHOR]