Phytotoxic Effects Research Articles

Biological effectiveness of Tebuconazole under three commercial names and Epoxyconazole for control of Karnal Bunt in the field

Commercial fungicides Opus, Tacora, Velficur, and Zoll, were evaluated in the field, to determine their biological effectiveness to control karnal bunt (Tilletia indica) of wheat. A completely randomized design was used with four replications. Twenty heads in each replication of experimental line KBSUS were inoculated during the boot stage with an allantoid sporidial suspension (10,000/mL). Commercial rates indicated in the containers of each product were followed. The first application was carried out ten days after inoculation (Zadoks stages 56-58), and the second one ten days later. Inoculated spikes were threshed by hand and the healthy and infected kernels were counted to determine the percentage of infection. Other variables evaluated were a thousand grain weight (g) and grain weight per plot (kg). The biological effectiveness of the products evaluated were Opus 95.1, Tacora 82.5, Velficur 76.1, and Zoll 59.2 %. The untreated inoculated check had a mean of 81.7 % infection. There were statistical differences for the products evaluated for level of infection after arcsin transformation (Tukey, p = 0.05), and the coefficient of variation was 8.30 %. The average a thousand grain weight per treatment was 38.3, 38.7, 38.6, and 39.2 g, for Opus, Tacora, Velficur, and Zoll, respectively, and 35.7 g for the untreated inoculated check, while the average grain weight per plot was 0.396 kg, 0.388, 0.371, and 0.375, respectively, and 0.291 for the untreated inoculated check. No phytotoxic effects of treatments applied to the wheat plant were observed.

Tannins and copper sulphate as antimicrobial agents to prevent contamination of Posidonia oceanica seedling culture for restoration purposes

Seed-based restoration methods are increasingly recognized as a relevant tool contributing to halt and reverse the loss of seagrass meadows while providing genetic and evolutionary benefit for the conservation of these habitats. Ad-hoc protocols aimed at maximizing the survival of plantlets obtained from seeds in cultivation systems are therefore required. Previous trials of seedling culture of Posidonia oceanica, the dominant seagrass of the Mediterranean Sea, recorded up to 40% loss due to mould development. In this study we aim to (i) identify the putative causal agents of seed decay and (ii) test the efficacy of copper sulphate (0.2 and 2 ppm) and of tannin-based products derived from chestnut, tara and quebracho in reducing seed and seedling decay, while assessing possible phytotoxic effects on plant development. Halophytophthora lusitanica, H. thermoambigua and a putative new Halophytophtora species were identified as possible causal agents of seed loss. The antimicrobial agents (copper and tannins) reduced seed contamination by 20%, although copper sulphate at 2 ppm strongly inhibited the root growth. Among tannins, chestnut and tara reduced seeds germination by up to 75% and decreased shoot and root development, while quebracho showed a less severe phytotoxic effect. The use of copper sulphate at 0.2 ppm is therefore recommended to prevent P. oceanica seedling loss in culture facilities since it reduces seed contamination with no phytotoxic effects. Our results contribute to improving the seedling culture of one the key species of the Mediterranean Sea, increasing propagule availability for restoration purposes.

Evaluating the impact of different biochar types on wheat germination.

This study assessed sustainable solutions for organic waste management, focusing on biochar derived from kitchen waste. The characteristics and phytotoxicity effects of biochar produced from four different types of kitchen waste were investigated in view of potential agricultural applications. Analysis of the chemical and physical properties of the different biochar samples by X-ray fluorescence and Fourier transform infrared spectroscopy revealed a nutrient-rich composition with carbon, calcium, and potassium contents that ranged from 35 to 48%, from 1.6 to 24%, and from 1.5 to 28.5%, respectively. In phytotoxicity tests, the highest germination rate (45%) was observed with Coffee residue biochar obtained at 300°C (application rate of 1%) and the longest shoot length (25cm) with orange peel biochar obtained at 300°C (application rate of 1%). Germination rate and shoot length were not significantly different between biochar-exposed soils and control soils (without biochar), indicating no toxic effect due to biochar addition. Washing biochar improved germination rates significantly (control: 98%; potato peel biochar: 92%; banana peel biochar: 83%). The longest shoot length (8.3cm) was obtained with the washed potato peel biochar (pyrolysis temperature = 400°C) extract. These findings suggest that biochar can be safely used as a soil amendment without harming the environment or hindering plant growth. The Tukey honestly significant difference (HSD) test results further emphasized the influence of different factors, such as pyrolysis temperature and feedstock type, in biochar applications.

A study on the effect of Hypericum perforatum L. extract on vanadium toxicity in Allium cepa L.

The growth of industrialization growth the risk of vanadium (V) contamination. The objective of this study was to examine the impact of 200 µg L− 1 VCI3 -induced toxicity as well as the potential protective effect of 187.5 mg L− 1 and 375 mg L− 1Hypericum perforatum (H. perforatum) extracts against this toxicity on the Allium cepa (A. cepa) model organism. For this purpose, a series of investigations were conducted on the growth physiology alterations (germination percentage, root elongation, weight gain), cytogenetic alterations (mitotic index, micronucleus, chromosomal aberrations), biochemical alterations (malondialdehyde, superoxide dismutase, catalase) and defects in meristematic tissue in A. cepa. In addition, the phenolic compound content of H. perforatum extract was determined by the LC/MS-MS method. V application negatively affected all the investigated parameters and caused a serious phytotoxic and genotoxic effect as well as oxidative stress in A. cepa. Conversely, no statistical difference was observed between the parameters of the groups treated with H. perforatum extract and those of the control group. The administration of H. perforatum extract combined with V resulted in a notable enhancement in germination percentage, root elongation, weight gain, mitotic index value, chlorophyll a level and chlorophyll b level. Additionally, it led to a reduction in micronucleus and chromosomal aberrations frequencies, as well as meristematic tissue defects. Furthermore, LC/MS-MS analysis demonstrated that H. perforatum extract contains phenolic compounds, including catechin, epicatechin, quercetin, oleuropein and rutin, which confer antioxidant properties to the extract. The study provided clear evidence that H. perforatum extract attenuates the toxic effects of V in A. cepa, which can be attributed to its high content of bioactive phenols. The findings of the study indicate that H. perforatum extract may serve as a protective natural agent for daily use against heavy metal toxicity.

Ecotoxicological Impact of Cigarette Butts on Coastal Ecosystems: The Case of Marbella Beach, Chile

Cigarette butts (CBs) are a major source of persistent pollution in coastal ecosystems, introducing harmful chemicals and microplastics into the environment. This study assesses the ecotoxicological impact of CB leachates on Marbella Beach, Chile, by analyzing the metal contamination and its phytotoxic effects on Lactuca sativa and Lolium perenne. Three scenarios were evaluated: CBs alone, CBs mixed with sand, and sand alone. Leachate analysis revealed significant concentrations of iron and zinc, with higher toxicity observed in scenarios involving CBs. Ecotoxicological assays demonstrated that cigarette butt leachates severely inhibited seed germination and plant growth, particularly in Lactuca sativa, which showed greater sensitivity compared to that of Lolium perenne. The results underscore the partial mitigating role of sand, although it was insufficient to prevent the toxic effects of CBs. The persistence of cellulose acetate in the environment and the continued release of hazardous chemicals highlight the ecological risks posed by cigarette butt pollution. These findings emphasize the need for improved waste management strategies and the development of biodegradable cigarette filters to reduce environmental contamination in coastal areas.

The Evaluation of Compost Maturity and Ammonium Toxicity Using Different Plant Species in a Germination Test

The determination of the maturity of compost and other organic fertilizers is very important because of possible phytotoxic or phytostimulating effects. The maturity of compost can be assessed on the basis of chemical analyses, and a germination test with different test plants is most often used to determine phytotoxicity. In this research, the maturity of compost produced from the plant residues subsequent to the maintenance of green public areas was assessed using the results of chemical analyses. Simultaneously, a germination test was carried out with the four test plant species (cucumber, garden cress, triticale, and barley) to determine the phytotoxicity of compost extract in a ratio of 1:2.5 v/v (1:3.3 w/v) and 1:10 v/v (1:13.3 w/v) and the three ammonium N solutions (in the concentrations of 200, 400, and 600 mg/L NH4-N). According to the chemical properties of compost (primarily the C/N, NH4-N/NO3-N ratios, and the NH4-N concentration) and the germination test with cucumber and garden cress, we may conclude that the tested compost was mature and that we did not expect a phytotoxic effect. The choice of a plant is very significant because the germination test with a compost extract demonstrated an undoubted phytostimulating effect on the garden cress and cucumber, with a more pronounced phytostimulating effect of the 1:10 than that of the 1:2.5 v/v compost extract. No such effect was detected on the monocotyledonous test plants triticale and barley since the 1:10 v/v extract had no significant effect, and the 1:2.5 v/v extract had a phytotoxic effect, moderate on the triticale and high on barley. The conclusion is that garden cress and cucumber are suitable test plants for the determination of compost’s phytostimulative effect, but they are not suitable for the determination of phytotoxicity for monocotyledonous plants, especially if the cause of phytotoxicity is a non-ammonium component. Barley is the most suitable species for the determination of compost’s non-ammonium phytotoxicity and nitrogen’s ammonium-form phytostimulative or phytotoxic effect. It would be very useful to conduct a comparative germination test with the compost extracts in the ratios 1:2.5 and 1:10, whereby the 1:2.5 extract would be used as a test of phytotoxicity, and the 1:10 extract for the test of a phytostimulating effect.

Isolation, characterization, and analysis of pure compounds from Leea macrophylla leaf extract for antibacterial, antidiabetic, cytotoxicity and phytotoxicity

This research aims to isolate, characterize, and analyze pure compounds from Leea macrophylla leaf extract to investigate its antibacterial, antidiabetic, cytotoxic, and phytotoxic effects. Fresh leaves were collected, dried, and subjected to methanol extraction to obtain a crude extract. From the petroleum ether fraction (PEF) of this extract, three fractions—designated LM1, LM2, and LM3—were prepared using column chromatography. The fractions were tried to be characterized in search for single compound by instrumental technique like ATR-FTIR, 1H NMR and 13C NMR but the 1H NMR and 13C NMR spectra were found complex which were difficult to interpret. To dispel the doubt and get clear idea about the structure, GC-MS analysis of the compounds was carried out whose result showed that all the three extracts were decomposed to several small organic compounds that made the structure elucidation difficult. For this complication, the characterization of the extracts was not possible. Numerous compounds were identified in the methanol extract of L.macrophylla through GC-MS analysis. Among these compounds, Benzene, 1,2,3-trimethyl- and Undecane were found in higher percentages in LM1. LM2 contained Azulene and Bicyclo [4.4.1]undeca-1,3,5,7,9-pentaene, while LM3 was characterized by the presence of 9,9-Dimethoxybicyclo [3.3.1]nona-2,4-dione and 11-(2-Cyclopenten-1-yl)undecanoic acid, among others. The antibacterial activity of these fractions was evaluated against various bacterial strains, demonstrating broad-spectrum effectiveness. LM1 fraction showed the highest antibacterial activity against Proteus sp. With zone of inhibition 25 mm and weak activity against S. sonnei with zone of inhibition 5 mm. LM2 showed the highest activity to both E. cocci and P. aeruginosa with the zone of inhibition of 18 mm and comparatively lower but significant against Proteus sp. LM3 was highly active to S. sonnei with zone of inhibition 20 mm and lower but quite significant against Proteus sp. Moreover, the anti-diabetic potential was assessed, with LM1 showing the strongest α-amylase inhibitory activity, outperforming quercetin (standard). The IC50 values of LM1, LM2, LM3, and quercetin were 57.36 μg/mL, 100.66 μg/mL, 164.92 μg/mL, and 97.45 μg/mL, respectively. In addition, cytotoxicity was assessed using a brine shrimp lethality bioassay, and phytotoxicity was evaluated through seed germination and growth assays. The results suggest that L.macrophylla leaf extracts have potential applications in antimicrobial, antidiabetic, and anti-cancer contexts. This comprehensive study bridges gaps in knowledge surrounding L.macrophylla's multifaceted properties, offering insights into its therapeutic and ecological potential for healthcare and environmental management.

Acute Phytotoxicity and Antifungal Effect of Nanochitosan Particles on Colletotrichum fructicola with Low Susceptibility to Chitosan.

Colletotrichum fungus complex affects several crops and tropical products, which suffer significant losses due to anthracnose. The use of chitosan nanoparticles (CNPs), alone or in combination with bioactive compounds, has been recommend for agronomic applications. However, there is very little information on their phytotoxicity, and there is no information about the effect on microorganisms with low susceptibility to chitosan. This work aims to compare their antifungal effect against isolates of C. fructicola with low susceptibility to chitosan and to study the toxicological effects of CNPs on the germination of lettuce (Lactuca sativa) and radish (Raphanus sativus) seeds. Levels of phytotoxicity of high-to-very high and moderate-to-very high were observed for lettuce and radish seeds, respectively, with greater detrimental effects on the radicle elongation after exposure to CNPs concentrations of 4-5g L-1. For the three C. fructicola isolates, the CNPs did not inhibit the fungal growth; however, the cell viability decreased as the CNPs concentration increased, and a complete inhibition of the viability was found for H4-1 and 003 isolates at a CNPs concentration of 5g L-1. Morphometric alterations characterized by a reduction in the average length of the terminal hyphae, distortion, and a higher number of branches in the hyphae, were observed. To our knowledge, this is the first report where the effect of nanochitosan particles in Colletotrichum fructicola, with experimentally proven low sensitivity to chitosan, was studied.

Allelopathic and phytotoxic activity of essential oil of Elaeagnus angustifolia flowers and its major constituents on Amaranthus retroflexus and Lolium perenne

This study investigated the allelopathic and phytotoxic effects of Elaeagnus angustifolia flower essential oil (EO) and its major constituents. Forty-one compounds were identified by GC–MS, accounting for 96.93% of the total oil, with the main compounds being ethyl cinnamate and methyl cinnamate. The allelopathic assay of the EO completely suppressed the seed germination of Lolium perenne and Amaranthus retroflexus at 22.22 mg/mL air treatment. Phytotoxic activities of ethyl cinnamate and methyl cinnamate were much stronger than those of the EO against L. perenne, with IC50 values of 0.386, 0.396, and 7.159 mg/mL, respectively. The strength of the phytotoxic activity of the major constituent ethyl cinnamate, and the mixture of ethyl cinnamate and methyl cinnamate was comparable to that of the commercial herbicide glyphosate in terms of suppressing root elongation in A. retroflexus, with IC50 values of 0.049, 0.076, and 0.017 mg/mL, respectively, indicating a possible synergistic effect of the major compounds.

Response of crop seed germination and primary root elongation to a binary mixture of diclofenac and naproxen.

Non-steroidal anti-inflammatory drugs, diclofenac (DCF) and naproxen (NPX), represent a group of environmental contaminants often detected in various water and soil samples. This work aimed to assess possible phytotoxic effects of DCF and NPX in concentrations 0.1, 1 and 10 mg/L, both individually and in binary mixtures, on the seed germination and primary root elongation of crops, monocots Allium porrum and Zea mays, and dicots Lactuca sativa and Pisum sativum. Results proved that the seed germination was affected by neither individual drugs nor their mixture. The response of primary root length in monocot and dicot species to the same treatment was different. The Inhibition index (%) comparing the root length of drug-treated plants to controls proved to be approximately 10% inhibition in the case of dicots lettuce and pea, and nearly 20% inhibition in monocot leek, but almost 20% stimulation in monocot maize. Assessment of the binary mixture effect confirmed neither synergistic nor antagonistic interaction of DCF and NPX on early plant development in the applied concentration range.

Phytochemical profiling and biological evaluation of the residues from industrial hemp (Cannabis sativa L.) inflorescences trimming: Focus on water extract

The study focused on investigating the phytochemical composition and bio-pharmacological properties of a water extract obtained from industrial hemp by-products, after trimming female inflorescences of Cannabis sativa L., cultivar Kompolti. The extract was found to be rich in phenolic compounds, particularly gallic acid, catechin, coumaric acid, ferulic acid, and benzoic acid. It also contained significant amounts of cannabidiolic acid and cannabigerolic acid as the main terpenophenols. To assess the biological potential of the extract, various ecotoxicological assays were conducted. The extract did not show significant phytotoxic effects on seedling germination in the allelopathic assay. In the brine shrimp (Artemia salina) lethality test, the LC50 value was 1.726 mg/mL, and in the Daphnia magna test, the extract showed no cardiotoxicity effects at the same concentration; thus, confirming its biocompatibility with these eukaryotic organisms. Additionally, the extract did not induce cytotoxicity in the murine C2C12 cell line till to the concentration of 1000 μg/mL. In isolated mouse prostate specimens, the extract (10–1000 μg/mL) also prevented LPS-induced gene expression of pro-inflammatory cytokines, namely tumor necrosis factor (TNF)α, interleukin (IL)-6, and IL-1β. Furthermore, the extract exhibited inhibitory effects on the growth of pathogenic bacterial, fungal, and dermatophyte species commonly associated with prostatitis. These results suggest that the residual powder from female inflorescence trimming can be considered an innovative plant material from the industrial hemp supply chain that deserves to be valorised in terms of recycling and upcycling; thus, reducing the environmental impact of the by-products and also opening the way for innovative health-promoting agents.

Pruning date and hydrogen cyanamide effects on growth and yield of grapevine var. Cabernet Sauvignon

Harvesting the grapes before the monsoon season is crucial to ensure the quality of berry and bunches. This study aims to identify the optimal window for pruning and hydrogen cyanamide (HC) application to prepone the berry harvesting. The experiment was conducted in randomized complete block design with five treatments and four replications. Treatments were five different pruning dates in 2021: Jan. 17, Jan. 24, Jan. 31, Feb. 7 and Feb. 14, followed by 5% HC application one week after pruning. Annual growth stages of grapevine were recorded by using modified E-L growth stage; reproductive attributes recorded during flowering; and vine yield and berry quality attributes recorded at harvesting. The earlier pruning resulted earlier budburst compared to late pruning. Vines prunefed after Feb. 7 had <50% budburst, while vines pruned before Feb. 7 reached 50% budburst, exhibiting no differences in number of days needed to achieve it. Jan. 17 pruning had the highest budburst (%) and bud fruitfulness (%), where pruning on Feb. 7 had lower values. Average bunch weight did not differ while berry quality attributes differed between treatments for the same day harvest. The negative responses in late pruned and HC treated vines, potentially attributed to the phytotoxic effect of HC on tender buds near the natural time of dormancy break. The early pruning and subsequent application of HC triggered earlier budburst, and advances flowering and harvesting of berries in grapevine. This research demonstrated a potential techniques for advancing harvesting time (2-3 weeks) in grapevine.

Impact nano- and micro- form of CdO on barley growth and oxidative stress response

The objective was investigated the effects of CdO and nano-CdO as potential toxic pollutants on growth and redox response of barley. CdO and nano-CdO have been found to cause significant phytotoxicity in barley seedlings, with nano-CdO increasing plant tissue cadmium accumulation. This accumulation is linked to growth retardation and oxidative stress. Low molecular weight antioxidants like restored glutathione and ascorbate have been found to increase the activity of glutathione peroxidase (GPX), glutathione-S-transferase (GSTs), and ascorbate peroxidase (APX) in green tissues. Catalase (CAT) activity increased from 50 % with 100 mg/l CdO to 70 % with 1000 mg/l and nano-CdO. The observed disturbance in redox balance signals the upregulation of corresponding genes. Antioxidant enzyme isoform gene transcripts increased for SODB, CAT2, and APX. Cadmium buildup in root cells causes oxidative stress, leading to upregulation of SOD, CAT, GR, and GSTs isoform genes as well as protein carbonylation, sulfhydryl group degradation, and MDA accumulation. CdO and nano-CdO have similar phytotoxic effects, but bioavailability affects biochemical and molecular responses.

Improved chickpea growth, physiology, nutrient assimilation and rhizoremediation of hydrocarbons by bacterial consortia.

Soil pollution by petroleum hydrocarbons (PHCs) reduces yield by changing the physico-chemical properties of soil and plants due to PHCs' biotoxicity and persistence. Thus, removing PHCs from the soil is crucial for ecological sustainability. Microbes-assisted phytoremediation is an economical and eco-friendly solution. The current work aimed to develop and use bacterial consortia (BC) for PHCs degradation and plant growth enhancement in hydrocarbon-contaminated soil. Initially, the enriched microbial cultures (that were prepared from PHCs-contaminated soils from five distinct regions) were obtained via screening through microcosm experiments. Afterward, two best microbial cultures were tested for PHCs degradation under various temperature and pH ranges. After culture optimization, isolation and characterization of bacterial strains were done to construct two BC. These constructed BC were tested in a pot experiment for hydrocarbons degradation and chickpea growth in PHCs contaminated soil. Findings revealed that PHCs exerted significant phytotoxic effects on chickpea growth and physiology when cultivated in PHCs contaminated soil, reducing agronomic and physiological traits by 13-29% and 12-43%, respectively. However, in the presence of BC, the phytotoxic impacts of PHCs on chickpea plants were reduced, resulting in up to 24 - 35% improvement in agronomic and physiological characteristics as compared to un-inoculated contaminated controls. Furthermore, the bacterial consortia boosted chickpea's nutritional absorption and antioxidant mechanism. Most importantly, chickpea plants phytoremediated 52% of the initial PHCs concentration; however, adding BC1 and BC2 with chickpea plants further increased this removal and remediated 74% and 80% of the initial PHCs concentration, respectively. In general, BC2 outperformed BC1 (with few exceptions) in promoting plant growth and PHCs elimination. Therefore, using multi-trait BC for PHCs degradation and plant growth improvement under PHCs stress may be an efficient and environmentally friendly strategy to deal with PHCs pollution and toxicity.

Streptomyces fradiae Mitigates the Impact of Potato Virus Y by Inducing Systemic Resistance in Two Egyptian Potato (Solanum tuberosum L.) Cultivars

In this study, the impact of culture media filtrate of QD3 actinobacterial isolate on two potato cultivars, Spunta and Diamond, infected with potato virus Y (PVY) was investigated. Various parameters, including infection percentage, PVY virus infectivity, disease severity scoring, PVY optical density, photosynthetic and defense-related biochemical markers, enzymatic profiling, phenolic compounds, proline content, salicylic acid levels, and growth and yield parameters, were assessed to elucidate the potential of the QD3 actinobacterial isolate culture filtrate in mitigating PVY-induced damage. The physiological and biochemical characteristics of the QD3 actinobacterial isolate, including its salinity tolerance, pH preferences, and metabolic traits, were investigated. Molecular identification via 16S rRNA gene sequencing confirmed its classification as Streptomyces fradiae QD3, and it was deposited in GenBank with the gene accession number MN160630. Distinct responses between Spunta and Diamond cultivars, with Spunta displaying greater resistance to PVY infection. Notably, pre-infection foliar application of the QD3 filtrate significantly reduced disease symptoms and virus infection in both cultivars. For post-PVY infection, the QD3 filtrate effectively mitigated disease severity and the PVY optical density. Furthermore, the QD3 filtrate positively influenced photosynthetic pigments, enzymatic antioxidant activities, and key biochemical components associated with plant defense mechanisms. Gas chromatography‒mass spectrometry (GC‒MS) analysis revealed palmitic acid (hexadecanoic acid, methyl ester) and oleic acid (9-octadecanoic acid, methyl ester) as the most prominent compounds, with retention times of 23.23 min and 26.41 min, representing 53.27% and 23.25%, respectively, of the total peak area as primary unsaturated fatty acids and demonstrating antiviral effects against plant viruses. Cytotoxicity assays on normal human skin fibroblasts (HSFs) revealed the safety of QD3 metabolites, with low discernible toxicity at high concentrations, reinforcing their potential as safe and effective interventions. The phytotoxicity results indicate that all the seeds presented high germination rates of approximately 95–98%, suggesting that the treatment conditions had no phytotoxic effect on the Brassica oleracea (broccoli) seeds, Lactuca sativa (lettuce) seeds, and Eruca sativa (arugula or rocket) seeds. Overall, the results of this study suggest that the S. fradiae filtrate has promising anti-PVY properties, influencing various physiological, biochemical, and molecular aspects in potato cultivars. These findings provide valuable insights into potential strategies for managing PVY infections in potato crops, emphasizing the importance of Streptomyces-derived interventions in enhancing plant health and crop protection.

Insight into physiological and biochemical markers against formaldehyde stress in spider plant (Chlorophytum comosum L.).

Formaldehyde is a prominent volatile organic compound and also considered as an indoor air pollutant. Chlorophytum comosum, an indoor plant, has been reported to metabolize indoor formaldehyde. But the phytotoxic effects of formaldehyde, being a pollutant, on C. comosum are not well explored. Furthermore, C. comosum responses that can be considered as markers at the physiological and biochemical level against formaldehyde stress are not yet investigated. Therefore, the current research study was aimed to evaluate such potential markers against formaldehyde in C. comosum. Briefly, C. comosum was exposed to 5-, 10-, and 20-ppm formaldehyde doses in an airtight glass chamber. Plant samples were then taken to analyze morpho-anatomical, physiological, and biochemical responses after short (2, 4, and 6h), medium (12 and 24h), and extended durations (48 and 96h) for each tested dose. Application of 10 and 20ppm formaldehyde doses leads to a significant incline in enzymatic antioxidants. Formaldehyde concentration of 10ppm leads to a maximum increase in catalase (30.30 U/mg of protein), guaiacol peroxidase (135.64 U/mg of protein), and superoxide dismutase (44.76 U/mg of protein) compared to their respective controls. A significant change is also observed in non-enzymatic parameters, including total phenolic content, which ranged from 3.62mg GAE/g (control) to 10.51mg GAE/g, total antioxidants vary from 27.37% (control) to 85.05% in 20ppm formaldehyde, respectively. However, formaldehyde application negatively affected the physiological responses of C. comosum by reducing its photosynthetic rate, transpiration rate, and stomatal conductance. Additionally, extended exposure of C. comosum to 10- and 20-ppm formaldehyde doses leads to visible leaf damage. Principal component analysis indicated that enzymatic parameters including SOD, CAT, and GPX and non-enzymatic parameters including MDA, TPC, TFC, TAOs, carotenoids, TSS, and intercellular CO2 contributed the most to the total variance. Thus, these parameters have potential to serve as physiological and biochemical markers in C. comosum against formaldehyde stress.

Selectivity of pre-emergent herbicides in cassava (Manihot esculenta Crantz) and its relationship with the stem cutting planting system

Cassava (Manihot esculenta Crantz, Euphorbiaceae), an important source of food for millions of people in the world, is distributed mainly in Asia, Africa, Latin America, and the Caribbean. Weeds are important biotic constraints on cassava production, and herbicide application can provide effective weed control in this crop. However, the different possibilities of herbicide selectivity (factors associated and not associated with the plants) must be studied before implementation. The aim of this study was to evaluate the effects of the combination of different pre-emergence herbicides and two stem cutting planting systems (vertical and horizontal) on phytotoxicity and several agronomic traits of the cassava crop. The experiment was conducted through a factorial arrangement in a completely random design in Corrientes, Argentina. The factors studied were planting systems (horizontal and vertical position), weed control methods (hoeing or application of diuron, S-metolachlor, pendimethalin or clomazone, 625; 1920; 900 and 1000 g a.i. ha−1, respectively), and cropping seasons (2018–2019 and 2019–2020). The following variables were measured: phytotoxicity, plant height, relative plant stand, total weight of tuberous roots per plant, starch concentration of tuberous roots, and starch production per ha. The highest precipitations occurred in the 2018–2019 cropping season. The vertical planting system in combination with herbicides showed lower phytotoxicity values and higher values of plant height, starch concentration, and starch production per ha than the horizontal planting system. The highest phytotoxicity values were recorded with the application of diuron combined with the horizontal planting system and in the 2018–2019 season, with a 33.33% decrease in relative plant stand compared to the use of hoeing. Starch concentration remained unchanged with the use of clomazone and pendimethalin, whereas the effect of these herbicides on starch production varied with the cropping season, decreasing only in 2019–2020. Starch production was significantly lower with the use of S-metolachlor (up to 55.29% in 2018–2019) and of diuron (up to 60.57% in 2019–2020) than with the use of hoeing. In conclusion, phytotoxicity values were higher for the horizontal planting system than for the vertical system. The herbicide with the highest phytotoxic effect on the cassava crop was diuron; the effect increased when combined with the horizontal planting system in the cropping season with higher rainfall. This work provides the basis for integrated weed management concerning the use of herbicides and their selectivity according to planting systems for cassava crops.

Pelargonic acid’s interaction with the auxin transporter PIN1: A potential mechanism behind its phytotoxic effects on plant metabolism

Pelargonic acid (PA) is a saturated fatty acid commonly found in several organisms, that is known for its phytotoxic effect and its use as bioherbicide for sustainable weed management. Although PA is already commercialised as bioherbicide, its molecular targets and mode of action is unknown according to the Herbicide Resistance Action Committee. Therefore, the aim of this work was focusing on the way this natural active substance impacts the plant metabolism of the model species Arabidopsis thaliana. PA caused increase of secondary and adventitious roots, as well as torsion, loss of gravitropism and phytotoxic effects. Moreover, PA altered the cellular arrangement and the PIN proteins activity. Computational simulations revealed that the intermolecular interactions between PA and the polar auxin transporter protein PIN1 are very similar to those established between the natural auxin IAA and PIN1. However, under intracellular conditions, the PA-PIN1 binding is more energetically stable than the IAA-PIN1. These results suggest that PA could act as an auxin-mimics bioherbicide. The exogenous application of PA would be responsible for the alterations observed both at structural and ultrastructural levels, which would be caused by the alteration on the transport of auxins into the plant, inducing root inhibition and ultimately total stop of root growth.

Biochar addition influences C and N dynamics during biochar co-composting and the nutrient content of the biochar co-compost

This study investigated the effects of corn cob biochar (CCB) and rice husk biochar (RHB) additions (at 0%, 5%, and 10% w/w) on nitrogen and carbon dynamics during co-composting with poultry litter, rice straw, and domestic bio-waste. The study further assessed the temperature, moisture, pH, and nutrient contents of the mature biochar co-composts, and their potential phytotoxicity effects on amaranth, cucumber, cowpea, and tomato. Biochar additions decreased NH4+-N and NO3- contents, but bacteria and fungi populations increased during the composting process. The mature biochar co-composts showed higher pH (9.0–9.7), and increased total carbon (24.7–37.6%), nitrogen (1.8–2.4%), phosphorus (6.5–8.1 g kg−1), potassium (26.8–42.5 g kg−1), calcium (25.1–49.5 g kg−1), and magnesium (4.8–7.2 g kg−1) contents compared to the compost without biochar. Germination indices (GI) recorded in all the plants tested with the different composts were greater than 60%. Regardless of the biochar additions, all composts treatments showed no or very minimal phytotoxic effects on cucumber, amaranth and cowpea seeds. We conclude that rice husk and corn cob biochar co-composts are nutrient-rich and safe soil amendment for crop production.

Elucidation of biochemical and physiological modulations in Triticum aestivum induced by green synthesized nitrogen-enriched zinc nano-complexes

This study investigates the efficacy of a green synthesized nitrogen-rich zinc complex (Zn-NC) using quinoline (C9H7N) as the nitrogen-rich substrate to enhance growth and biochemical properties in wheat (Triticum aestivum). The performance of Zn-NC was compared to standard zinc oxide nanoparticles (ZnO-NPs). Both Zn-NC and ZnO-NPs were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD), and dynamic light scattering (DLS). Three concentrations (100, 200, and 500 ppm) of each compound, along with a control, were applied to local soil samples (n=3). The physiological (biomass, elongation) and biochemical effects (chlorophyll, carotenoids, flavonoids, and phenols) on wheat were investigated. Potential phytotoxic effects were evaluated to establish the biostimulants' safety thresholds. Plants treated with green Zn-NC showed an average increase in shoot length of 25 % compared to the control group. The chlorophyll content in plants treated with ZnO-NPs increased by 18 %, while those treated with green Zn-NC increased by 12 % compared to control. Application of ZnO-NPs resulted in a 30 % increase in total yield, whereas green Zn-NC treatment led to a 22 % yield increase. The root biomass of plants treated with ZnO-NPs increased by 28 %, and those treated with green Zn-NC saw a 20 % increase compared to controls. Based on the optimization of overall results, the ZnO NPs showed phytotoxic effects at concentrations above 200 ppm, while green Zn-NC exhibited no significant phytotoxicity even at concentrations up to 300 ppm. This study delineates the optimal concentrations of Zn-NC and ZnO-NPs that can enhance nutrient delivery and yield in cereal crops while mitigating phytotoxic risks. The findings provide valuable insights into applying nano-biostimulants in agroecosystems, highlighting their potential to improve productivity and sustainability in agriculture.