Phytotoxic Potential Research Articles

Chlorhexidine residues in sludge from municipal wastewater treatment plants: analytical determination and toxicity evaluation

In this work, a procedure for the sensitive and selective determination of chlorhexidine in sludge from municipal sewage treatment plants (STPs) based on matrix solid-phase dispersion (MSPD) and liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) was optimized and validated. Analysis of sewage sludge samples, obtained from different STPs in Northwest Spain from 2018 to 2021, showed that chlorhexidine was ubiquitous in this environmental compartment with concentrations between 0.3 and 16 µg g−1. The toxicity of this pollutant was assessed in in vitro assays considering three different model organisms: Candida albicans, Escherichia coli, and Staphylococcus aureus. C. albicans was the most sensitive of the tested microorganisms to chlorhexidine with a lethal threshold concentration of 0.1 mg L−1. Thus, the lowest observed sludge residue was 3 times higher than the acute toxicity threshold measured for C. albicans. Moreover, E. coli and S. aureus were also affected at chlorhexidine concentrations around 1.8 mg L−1 and 0.5 mg L−1, respectively. So, chlorhexidine residues might affect the population of microorganisms existing in STPs. In addition, the potential phytotoxicity of the compound was evaluated with germination experiments using different model seeds. At the evaluated dose (10 µg g−1 dried soil), chlorhexidine did not affect the germination of Sorghum saccharatum, Lepidium sativum, or Sinapis alba seeds. Thus, amending agriculture soils with chlorhexidine containing sludge is unlikely to affect the germination of plants.

BIOASSAY OF ALLELOPATHIC POTENTIAL OF BERMUDAGRASS AND SORGHUM ON GERMINATION AND RELATED TRAITS OF WEEDS ASSOCIATED WITH RICE

With growing concern towards human health and ecological concerns related to prolonged use of herbicides, research is undergoing globally for alternate weed managing methods. Allelopathy is one of the very efficient methods for management of weeds. Experiment was conducted during 2016 & repeated in 2017 under laboratory conditions in Kharif (summer) season using completely randomized design for allelopathic potential assessment of bermudagrass (Cynodon dactylon L.) and sorghum (Sorghum bicolor L.) with 03 replicates. The treatments under study comprised: control (check), bermudagrass & sorghum root & shoot powders @ 15 and 30 g kg-1 soil as well as water extracts @ 15 and 30 ml kg-1 soil. It is obvious from the present data that allelopathic plants powders & water extracts caused significant adverse effects on tested weeds i.e. Sawari (Echinochloa colonum L.), Saon (Echinochloaa crusgalli L.) and Kabah (Cyperus rotundus L.). Bermuda grass and sorghum water extracts exhibited strong allelopathic efficacy on germination, roots & shoots length, as well as fresh & dry biological weight of weeds included under study. It is further argued that greater inhibitory effects on weeds were caused by extracts prepared from bermudagrass and sorghum in comparison with their powders. Hence, it is evident from the results that bermudagrass & sorghum materials possess phytotoxic potential which can suppress growth of target plant. This allelopathic herbage could be utilized by soil incorporation or extract for weed management in rice as environment friendly strategy.

Phytotoxicity Effect of Pongamia Oil on Chilli

This study evaluated the phytotoxicity potential of pongamia oil on chilli plants. The pongamia oil at 0.5, 1.0, 2.5, 5.0 and 10% concentrations were evaluated under field conditions. The dose @ 0.5, 1.0 and 2.5% were observed to be safe with no phytotoxicity symptoms. Pongamia oil @ 5.0 and 10% caused the moderate and high phytotoxicity interfering with photosynthesis and plant growth.

Assessment of insecticidal, phytotoxicity, and fungistatic potential of chemically characterized Elaeis guineensis (Jacq) kernel oil

Palm kernel fixed oil (PKO) extracted by heat (HPKO) and cold-press (CPKO) was evaluated for contact toxicity against Callosobruchus chinensis (L.) at 0–1.5 mL/25 g of cowpea (Vigna unguiculata (L.) Walp) seeds and fungistatic potential against Aspergillus species. In addition, biochemical compounds in the oils were obtained using gas chromatography and mass spectrometric (GC-MS) analysis. One hundred percent mortality of C. chinensis was achieved with ≥1 mL HPKO dose levels while the same mortality was achieved with ≥0.75 mL CPKO dose levels at 24, 48, 72 and 96 h post treatment. Zones of inhibitions (cm) of A. niger (0.93 ± 0.07) and A. flavus (1.27 ± 0.15) with HPKO were comparably higher than zones of inhibitions of A. niger (0.20 ± 0.06) and A. flavus (1.13 ± 0.03) with CPKO. The relative abundance of major compounds in HPKO was Lauric acid > caprylic acid > capric acid while 9-Octadecenoic acid -, 2,3-bis[(trimethylsilyl)oxy]propyl ester > Butanoic acid trimethylsilyl ester > Tetradecanoic acid trimethylsilyl ester in CPKO. The higher percentage of lauric acid in HPKO may account for its greater insecticidal and fungistatic potentials.

Deverra triradiata Hochst. ex Boiss. from the Northern Region of Saudi Arabia: Essential Oil Profiling, Plant Extracts and Biological Activities.

Devrra triradiata Hochst. ex Boiss is an occasional plant species in the Northern region of Saudi Arabia. The shrub is favored on sandy desert wadis, gypsaceous substrate, and sandy gravel desert. In folk medicine, the plant is used for many purposes; to relieve stomach pains, against intestinal parasites, and for the regulation of menstruation. The present study describes the chemical composition of the essential oils (EOs) of different plant parts of D. triradiata. In vivo and in vitro biological activities of plant extracts and essential oils were also studied. Phenylpropanoids, elemicin (flowers: 100%), dillapiole (Stems: 82.33%; and seeds: 82.61%), and apiol (roots: 72.16%) were identified as the major compounds. The highest antioxidant activity was recorded for the EOs of roots and stems (IC50 = 0.282 µg/mL and 0.706 µg/mL, respectively). For plant extracts, ethyl acetate showed the highest antioxidant activities (IC50 = 2.47 and 3.18 µg/mL). EOs showed high antifungal activity against yeasts with low azole susceptibilities (i.e., Malassezia spp. and Candida krusei). The MIC values of EOs ranged between 3.4 mg/mL and 56.4 mg/mL. The obtained results also showed phytotoxic potential of plant extracts both on the germination features of Triticum aestivum seeds and the vegetative growth of seedlings.

Usnic Acid (+) Enantiomer in Alternative In Vitro Control of Burkholderia cepacia and Allelopathic Effect

Introduction: Allelopathic effects have a wide range of action, at the genetic and biochemical level, favoring the germination and survival of plants and, often, helping as a phytosanitary strategy in reducing infections that generate loss in the agro-industrial sector. However, in addition to pesticides, metabolites of natural origin have been identified as an important tool in combating phytopathogenic microorganisms and, due to their symbiotic activities in the environment, growth promoters of several plant species. This study aims to assess the antimicrobial activity against Burkholderia cepacia, allelopathic, and phytotoxic potential of the (+)− usnic acid (UA). Materials and Methods: The experiments were conducted in laboratory conditions using the compound at different concentrations and the test organism were Solanum lycopersicum. Results: The compound at 12.5 μg/mL was able to reduce >90% of the evaluated bacterial population and any significant toxic effects were observed on the germination. Conclusion: In addition, at 25 μg/mL, the UA did not interfere in the fresh and dry weight of the tomato, corroborating the potential of this compound as a biocontroller, since it does not cause a pronounced phytotoxic effect, selectively assessing a pathogenic microorganism.

P-Methoxycinnamic acid disturbs cellular respiration and increases the lignification of Euphorbia heterophylla roots

Herbicide-resistant plants evolved rapidly due to the recurrent use of active principles with only a few mechanisms of action. Today, discovering new herbicides is a pressing challenge. Here, the effects of p-methoxycinnamic acid were evaluated on root growth, cellular respiration, and lignification of the wild poinsettia weed (Euphorbia heterophylla L.). In primary roots, p-methoxycinnamic acid decreased root length and the mitotic index, followed by the loss of cell viability. At the cellular level, p-methoxycinnamic acid stimulated KCN-insensitive and KCN- and SHAM-insensitive respiration. Furthermore, it decreased KCN-sensitive respiration and ATP generation, a limiting factor for root growth. Disturbances in cellular respiration increased the H2O2 content and superoxide dismutase, catalase, and soluble peroxidase activity. p-Methoxycinnamic acid increased the activities of phenylalanine ammonia-lyase and cell wall-bound peroxidase. It also increased lignin, ferulic and p-coumaric acids, and cell wall-esterified p-methoxycinnamic acid. Collectively, these findings reveal the phytotoxic potential of p-methoxycinnamic acid on wild poinsettia. Field tests may point to new clues for using this compound as a potential herbicide.

Investigating the phytotoxic potential of Verbesina encelioides: effect on growth and performance of co-occurring weed species.

Allelopathy has been proposed as an efficient mechanism of invasion by plant species via growth inhibition and suppression of the resident plant community. Verbesina encelioides (Cav.) Benth. & Hook. f. ex A. Gray (golden crownbeard; Asteraceae), a native of south-western USA and Mexican Plateau, is an emerging troublesome invasive weed species of north-western states of India. We investigated the allelopathic potential of the aqueous extracts prepared from the fresh foliage and leaf litter of V. encelioides on its co-occurring species, Amaranthus viridis and Senna occidentalis. Phytotoxicity bioassay showed concentration-dependent (control < 0.5% < 1% < 2% < 4% extract) inhibition of growth and photosynthetic parameters in the test plants. Both the extracts induced ~ 50% inhibition of germination compared to control at 4% concentration. The maximum synthesis effect (collective effect on seedling length and dry weight) was observed to be - 0.69 and - 0.62 in A. viridis and - 0.68 and - 0.57 in S. occidentalis for the fresh leaf and leaf litter extracts, respectively, at 4% concentration. Also, an antagonistic concentration-dependent impact was observed on the photosynthetic pigments (total chlorophyll and chlorophyll a content) and photosynthetic efficiency. The liquid chromatography-mass spectrometry assay of leaf extracts revealed the presence of 15 allelochemicals including phenolic acids, flavonoids, phytosterols, phytophenols, dicarboxylic acid, guanidine, and triterpenes. Of these, 14 compounds were present in both fresh and leaf litter materials. However, a guanidine derivative, galegine, was only found in the fresh leaf material of the plant. The findings support the novel weapon hypothesis and suggest that V. encelioides competitively excludes its neighboring plants by virtue of allelopathic interference.

Comparative efficacy of bio-selenium nanoparticles and sodium selenite on morpho-physiochemical attributes under normal and salt stress conditions, besides selenium detoxification pathways in Brassica napus L.

Selenium nanoparticles (SeNPs) have attracted considerable attention globally due to their significant potential for alleviating abiotic stresses in plants. Accordingly, further research has been conducted to develop nanoparticles using chemical ways. However, our knowledge about the potential benefit or phytotoxicity of bioSeNPs in rapeseed is still unclear. Herein, we investigated the effect of bioSeNPs on growth and physiochemical attributes, and selenium detoxification pathways compared to sodium selenite (Se (IV)) during the early seedling stage under normal and salt stress conditions. Our findings showed that the range between optimal and toxic levels of bioSeNPs was wider than Se (IV), which increased the plant’s ability to reduce salinity-induced oxidative stress. BioSeNPs improved the phenotypic characteristics of rapeseed seedlings without the sign of toxicity, markedly elevated germination, growth, photosynthetic efficiency and osmolyte accumulation versus Se (IV) under normal and salt stress conditions. In addition to modulation of Na+ and K+ uptake, bioSeNPs minimized the ROS level and MDA content by activating the antioxidant enzymes engaged in ROS detoxification by regulating these enzyme-related genes expression patterns. Importantly, the main effect of bioSeNPs and Se (IV) on plant growth appeared to be correlated with the change in the expression levels of Se-related genes. Our qRT-PCR results revealed that the genes involved in Se detoxification in root tissue were upregulated upon Se (IV) treated seedlings compared to NPs, indicating that bioSeNPs have a slightly toxic effect under higher concentrations. Furthermore, bioSeNPs might improve lateral root production by increasing the expression level of LBD16. Taken together, transamination and selenation were more functional methods of Se detoxification and proposed different degradation pathways that synthesized malformed or deformed selenoproteins, which provided essential mechanisms to increase Se tolerance at higher concentrations in rapeseed seedlings. Current findings could add more knowledge regarding the mechanisms underlying bioSeNPs induced plant growth.Graphical

Effect of the Systemic Neonicotinoid Insecticide Dinotefuran on Leaf-level Photosynthesis in Loblolly Pine (Pinus taeda)

ABSTRACT Bark beetles (Coleoptera: Curculionidae: Scolytinae) are a common pest in loblolly pine (Pinus taeda L.) plantations, and climate intensification threatens to increase the range of bark beetle infestation and vulnerability of loblolly pine. New insecticides and management options are needed to maintain loblolly pine plantation productivity, mitigating increased bark beetle risk. The systemic neonicotinoid insecticide dinotefuran (Safari 20SG systemic insecticide, Valent USA, LLC), is utilized by nursery managers to protect loblolly pine from bark beetles, but there is little published literature on the insecticide’s potential phytotoxicity. The objective of this study was to evaluate the effect of dinotefuran on the leaf-level photosynthesis of three loblolly pine genotypes. Dinotefuran was applied to lower tree boles, and photosynthetic measurements occurred two months later. Dinotefuran did not significantly impact leaf-level gross photosynthesis (Pgmax), light-saturated net photosynthesis (Pnet) or dark respiration (Rd); nor was there any significant genotypic variation in responses. Dinotefuran appears to be a promising insecticide for bark beetle prevention without risk of foliar toxicity.

Contrasting impacts of mixed nonionic surfactant micelles on plant growth in the delivery of fungicide and herbicide

HypothesisNonionic alkyl ethoxylate surfactants are widely used in agrochemicals to facilitate the permeation of systemic herbicides and fungicides across the plant waxy film. Industrial grade surfactants are often highly mixed and how the mixing affects their interactions with pesticides and wax films remains largely unexplored. A better understanding could enable design of mixed nonionic surfactants for herbicides and fungicides to maximize their efficiency and reduce wastage whilst controlling their impact on plant wax films. ExperimentIn this study, nonionic surfactants with general structure n-oxyethylene glycol monododecyl ether (C12En) were used to form surfactant mixtures with the same average ethoxylate numbers but different hydrophilic-lipophilic balance (HLB) values. Their mixed micellar systems were then used to solubilize a herbicide diuron (DN) and a fungicide cyprodinil (CP), followed by plant wax solubilization upon contact with wax films. These processes were monitored by 1H NMR and SANS. FindingPesticide solubilization made surfactant micelles effectively more hydrophobic but subsequent wax dissolution caused pesticide release and the restoration of the micellar amphiphilicity. Nonionic surfactants with lower HLBs form larger nanoaggregates, show enhanced wettability, and have better ability to solubilize and permeate pesticides across the wax film, but may cause significant damage to plant growth. These observations help explain why herbicides applied on weeds would benefit from surfactants with lower HLB values while fungicides require surfactants with HLBs to balance between delivery efficiency and potential phytotoxicity risks.

How do native grasses from South America handle zinc excess in the soil? A physiological approach

The excess of zinc (Zn) in vineyard soils promotes grape yield restraints. Thus, it is urgent to set up sustainable strategies aiming at decrease phytotoxic potential of Zn for crops. The selection on biochemical and physiological bases of wild plants to intercrop with perennial ones might be the key step to identify and characterize unknown mechanisms of metal tolerance in these plant species. This study aimed to evaluate the physiological and biochemical responses of native grasses of South America exposed to high Zn concentrations in the soil. The soil was sampled in a non-anthropized area and it was incubated with the following Zn amounts: 0, 30, 60, 120, or 180 mg Zn kg−1 soil. The native grass species considered were: Axonopus affinis, Paspalum notatum, and Paspalum plicatulum. Dry mass accumulation, the nutritional composition of plants, photosynthetic parameters, antioxidant enzyme activities, and oxidative stress indicators have been evaluated. A. affinis specie increased photosynthetic rate, pigments concentrations, and biomass production as Zn increased in soil. While it did not enhance the reactive oxygen species, and did not show lipid peroxidation under Zn excess. On the other hand, species P. plicatulum and P. notatum were more sensitive to Zn excess in the soil, showing oxidative injuries, which reduced plant growth. Hence, results show that A. affinis possess the physiological and biochemical features for controlling the Zn availability in the soil supporting, thus, the idea of its effective use in agronomical strategies for containing the Zn toxicity problem.

Phytotoxicity and Plant Defence Induction by Cinnamomum cassia Essential Oil Application on Malus domestica Tree: A Molecular Approach

Essential oils (EOs) are actively investigated as an alternative to numerous synthetic biocide products. Due to their large spectra of biological activities, the impact of EOs on non-target organisms should be characterized for biopesticide development purposes. In this study the potential phytotoxicity of Cinnamomum cassia EO (CEO) on apple trees (Malus domestica) was investigated in terms of oxidative burst (glutathione redox state) and damage (malondialdehyde). At 2%, CEO concentration the reduced glutathione leaf content drops from 269.6 ± 45.8 to 143 ± 28.4 nmol g−1FW, after 30 min, illustrating a rapid and strong oxidative burst. Regarding oxidative damage, malondialdehyde increased significantly 24 h post application to 10.7 ± 3.05 nmol g−1FW. Plant defence induction was previously suspected after trans-cinnamaldehyde (CEO main compound) application. Therefore, the elicitor potential was investigated by qRT-PCR, on the expression level of 29 genes related to major defence pathways (PR protein, secondary metabolism, oxidative stress, parietal modification). Multivariate analysis and increased expression levels suggest induction of systemic resistance. Hence, the present research illustrates the dose–dependent phytotoxicity of CEO in terms of lipid peroxidation. Transcriptional data illustrates the elicitor properties of CEO. These findings can help to design pest management strategies considering both their risks (phytotoxicity) and benefits (defence activation combined with direct biocide properties).

Chemical volatile composition and phytotoxic potential of Daphne gnidium L. leaves

Daphne gnidium L. (Thymelaeaceae) is an evergreen shrub from the Mediterranean area traditionally used for its medicinal and non-medicinal properties. Several studies showed its adverse impact on different targets including malignant cells, microbes, radicals, insects. The negative interactions between D. gnidium and other plant species have been rather neglected so far, as well as its chemical volatile composition. Therefore, this work aimed to assess the phytotoxic activity of D. gnidium on filter paper and soil in pre-emergence conditions by testing both the aqueous extract (10–100%) and the powder (0.25–1 g) obtained from the leaves as bioagrochemicals. The results showed that D. gnidium was able to significantly decrease seed germination and growth parameters of the receiver plants with different effectiveness (p-values < 0.05). Overall, Sinapis alba L. (Brassicaceae) was the most susceptible species followed by Lolium multiflorum Lam. (Poaceae) and Trifolium incarnatum L. (Fabaceae) while aqueous extract was more active than the powder. Solid-Phase Microextraction (SPME) sampling technique and Gas Chromatograph/Mass spectrometer (GC/MS) analyses were used to characterize the volatile fraction highlighting considerable differences in the composition of the analyzed samples. Hexahydrofarnesyl acetone (29.7%) followed by 3,7,11,15-tetramethyl-2-hexadecen-1-ol (28.3%) and β-damascenone (32.0%) followed by eudesma-1,4(15), 11-triene (27.1%) were detected as main volatile compounds of the powder and the aqueous extract, respectively.

Deciphering chemical profiling, pharmacological responses and potential bioactive constituents of Saussurea lappa Decne. Extracts through in vitro approaches

Despite advancement in modern medicines, plant derived medicines have still wide range utilities as they have less side effects and are cheap and biocompitable. Sassurea lappa is an extensively used plant in traditional medicinal formulations. Plant roots are used to cure various diseases including cancer, rheumatic pain, abdominal and nervous disorders. The present study was aimed for the evalution of biological potentials of methanolic and chloroform extracts of Saussurea lappa root, leaf, seed and flower. The methanolic and chloroform extracts were subjected to qualitative and quantitative phytochemical analyses. Identification of functional groups was performed using Fourier Transform infrared (FT-IR) spectroscopy. Antioxidant potential was determined via diphenyl-1-picrylhydrazyl (DPPH), total reducing power (TRP) and total antioxidant capacity (TAC) method, anti-hemolytic potential was conducted on human RBCs, antibacterial activity was evaluated against six American type culture collection (ATCC) and three multi drug resistance (MDR) strains, cytotoxic and phytotoxic potentials were evaluated through brine shrimp lethality assay and raddish seed assay respectively. Experiments were performed in triplicates and analysis of variance (ANOVA) was applied using statistics version-8.1. Phytochemical analysis revealed the presence of sixteen secondary metabolites. Fourteen functional groups were identified through FTIR. S. lappa root methanolic (SLRM) showed maximum antioxidant activity index (AAI-79.42%) whereas chloroform extract of leaves (SLLC) gave highest antibacterial activity with maximum zone of inhibition (ZOI) against Pseudomonas aeruginosa (21.4 mm). Maximum cytotoxicity was observed for SLRM with lethal dose concentration (LC50) of 58.8 µg/mL. However, root extracts showed significant phytotoxicity (15% germination). The current study investigated that bioactive compounds present in S. lappa leaves, seed, flower and roots were responsible for enhanced biological potentials. Further studies on isolation and characterization of these bioactive compounds may help in drug development. In future, we recommend different in-vitro and in-vivo studies to further confirm it biopharmacological potencies.

Does the application of herbicides with distinct mechanisms of action change enzymatic activity and grain yield of Clearfield® canola?

Herbicides have a high potential for phytotoxicity and generate oxidative stress, even on tolerant crops. The canola hybrid Hyola 571 CL obtained through Clearfield® technology shows tolerance to imidazolinones. Given the importance of this hybrid, this work assessed the effect of using herbicides with different mechanisms of action on the activity of antioxidant enzymes, ALA-D, gas exchange, and grain yield of canola hybrid tolerant to imidazolinones. Treatments applied to Hyola 571 CL canola hybrid were: control without herbicides, diclosulam, imazaquim, sulfentrazone, sulfentrazone + diuron pendimenthalin, flumioxazin, imazethapyr + imazapic, imazapic + imazapyr, imazethapyr, imazamox, nicosulfuron, chlorimuron, netsulfuron-methyl, iodosulfuron, and pyroxsulam. Seven, 14, 21, and 28 days after application we assessed herbicide phytotoxicity to canola. Antioxidant enzyme systems, variables related to plant physiology, and grain yield of Hyola 571 CL were also determined. It was observed that the hybrid, even tolerant, showed sensitivity to herbicides. Pendimethalin, flumioxazin, chlorimuron-ethyl, metsulfuron-methyl, and iodosulfuron were the most harmful to Hyola 571 CL. Commercial mixtures by [imazethapyr + imazapic] and [imazapic + imazapyr], as well as imazamox, were the most selective ones. Catalase was inhibited by most treatments. Sulfentrazone promoted the greatest negative interference along with its mixture with diuron and nicosulfuron, chlorimuron, and metsulfuron-methyl. The hybrid showed sensitivity to herbicides and the differences in gas exchange rates and other analyzes for the types of treatment do not result in productivity.

Impact of Achillea moschata Wulfen on germination and growth of weed species Echinochloa oryzoides (Ard.) Fritsch and Lolium multiflorum Lam

Weeding is a practice of primary importance both in conventional agriculture where the intensive use of herbicides can represent a significant environmental risk and in organic farming where this practice is prohibited. Therefore, the need to identify alternative means of controlling weeds is evident. In this respect, allelopathy proves to be a useful tool to be integrated with conventional agronomic techniques for the management of infesting flora. In this work, we investigated the phytotoxic potential of Achillea moschata Wulfen (Asteraceae) against Echinochloa oryzoides (Ard.) Fritsch and Lolium multiflorum Lam., two noxious plants for crops such as rice and wheat. Preliminary anti-germination assays were carried out in controlled conditions by testing both the powder (0.25 g) and the aqueous extract (1%, 10% and 20%) from the A. moschata aerial parts. The obtained results showed that the powder was more effective than the extract in inhibiting seed germination (up to –81.6% vs –48.8% at 20% concentration) and seedling development (up to –99.4% vs –75.9% at 20% concentration) of both target species, although L. multiflorum was more susceptible than E. oryzoides to treatments. Furthermore, the chemical composition of the two used matrices was characterized by Solid-Phase Microextraction (SPME) sampling technique and Gas Chromatograph/Mass spectrometer (GC/MS) analyses. Camphor (25.8% and 49.9%) and 1,8 cineole (25.9% and 20.7%) were the main constituents in the samples, followed by bornyl acetate (6.7%) in the powder and fragranol (10.5%) in the aqueous extract.

Short-term changes related to autotetraploidy in essential oil composition of Eucalyptus benthamii Maiden & Cambage and its applications in different bioassays

Some forest trees have been polyploidized to improve their traits and to supply new germplasms for breeding programs. As trees have a long juvenile stage, the early characterization of the chromosome set doubling effects is crucial for previous selection. Thus, we aimed to characterize the chemical variability of essential oils from diploid and autotetraploid germplasms (autotetraploid A and B) of Eucalyptus benthamii, as well as to evaluate their larvicidal and allelopathic effects. Autotetraploid A showed a higher essential oil yield than diploid and autotetraploid B, which did not differ quantitatively. Aromadendrene, viridiflorol and α-pinene were the major compounds in the diploid essential oil. In contrast, compounds were present in autotetraploids, such as 1,8-cineole, limonene, α-terpineol, and α-terpinyl-acetate. Essential oils from the diploid at 50–200 ppm were twice as larvicidal than those from autotetraploids against Aedes aegypti larvae. Considering the phytotoxicity bioassays using Lactuca sativa, essential oils from both ploidy levels affected root growth. Moreover, the essential oils inhibited shoot growth at all concentrations tested (187.5; 375; 750; 1500; and 3000 ppm). Autotetraploid A and B had the same effect on shoot growth as glyphosate. The essential oils had no cytogenotoxic effect on root meristematic cells of L. sativa, whereas phytotoxic potential was identified mainly in shoot growth. This work demonstrated a dramatic change in secondary metabolism (terpene composition) related to an increase in the ploidy level in Eucalyptus germplasms. In addition, we report the novelty of the chemical composition of essential oils among germplasms and their potential use as larvicidal and post-emergence weed control agents.

Relationship between Leachate Pollution Index and growth response of two willow and poplar hybrids: Implications for phyto-treatment applications.

Phytoremediation is a potentially suitable technique for the reclamation of toxic landfill leachate (LL) by decreasing its volume through water uptake and improving its composition by uptake, accumulation and amelioration of pollutants. We investigated the use of two parameters, the LL concentration and the Leachate Pollution Index (LPI), a method used to determine the phytotoxicity potential of a leachate source based on a weighted sum of its components, to set the best LL dilution to apply when poplar clone 'Orion' and willow clone 'Levante' are selected for phytoremediation. Cuttings were watered with five LL concentrations ranging from 0 to 100%. The poplar clone showed significantly higher values than the willow clone for lowest effective concentration index (LOEC) for leaf (i.e. 11.3% vs 10.5%; p=0.0284) and total biomass (i.e. 10.9% vs 10.6%; p=0.0402) and for lowest effective LPI for leaf (i.e. 12.3 vs 12.1; p=0.0359) and total biomass (i.e. 12.8 versus 12.2; p=0.0365), respectively, with effectiveness demonstrating the LOEC or LPI value at which the parameter is negatively affected. Photosynthetic rates were higher in poplar than willow in both control and the lowest LL dilution, but rapidly declined in both at higher LL dilutions. Although a direct translation of data from bench trials to field conditions should be investigated, we concluded that in the establishment phase, the poplar hybrid is more tolerant than the willow hybrid to LL. We also provide evidence for LPI as a potential predictor for setting LL irrigation levels in the initial phase of a phyto-treatment approach.

Eisenia fetida for vermiconversion of waste biomass of medicinal herbs: Status of nutrients and stability parameters

Vermiconversion possibility of waste biomass of two medicinal herbs Zingiber officinale and Curcuma longa has been investigated. The Eisenia fetida, an epigeic earthworm was used in the vermicomposting process. The vermicomposting caused shifting in pH towards neutral range, reduction in electrical conductivity, total organic carbon, C/N and C/P ratios whereas1.8–2.73 folds enhancement in macronutrients (TKN, AP, T Ca and T Mg) and ash contents in the substrate mixture. The heavy metals and trace elements content in the vermicompost were found within 3.25–1380 mg/kg and are under the permissible limits of compost applications. Besides, high germination index value in the vermicompost extract indicates loss of phytotoxicity and safe agricultural application potential of the end product. Finally, enhanced growth in Eisenia fetida confirms the application potential of harvested waste biomass as the raw materials for vermiconversion process.