Eco-friendly Herbicides Research Articles

Production of Metabolites from Bacterial Degradation of some Selected Herbicides in Pristine Soil.

The increasing use of herbicides has become worrisome as there have been reports on the harmful effects of herbicides on non-target species. This study monitored the fate and effects of three herbicides in pristine soil from Joseph Sarwuan Tarka University, Makurdi using GC-MS and laboratory culturing. Brevibacterium spp., Pseudomonas stutzeri, Bacillus flexus, Staphylococcus succinus, Paracoccus kawasakiensis, and Flavobacterium succinicans were found to degrade ButaForce yielding (1) 2,6-Diethylaniline; (2) 1 – tetradecene, (E); (3) 2-Sec-butyl-6-ethylaniline; (4) 2-Chloro-N-(2,6-diethylphenyl)-acetamide; (5) 1 – octadecene, alachlor and (6) 3 – Eicosene. On the other hand, PropaForce Plus was degraded by Pseudomonas viridiflava, Bacillus cereus, Flavobacterium columnare., and Staphylococcus saprophyticus producing (1) 4 – dimethylcumene; (2) 2,4 - Dichlorophenoxy methyl acetate and (3) Acetic acid (2,4-dichlorophenoxy)-2-ethylhexyl ester whereas force Up was degraded by Pseudomonas carboxydohydrogena, Bacillus flexus, Flavobacterium spp., and Phenilobacterium spp. yielding (1) 1 – Docosene; (2) 2-Hydroxy-1-(hydroxymethyl)-ethylhexyl ester and (3) 1,2,5-Oxadiazol-3-amine. Both Acinetobacter sp. and Lactobacillus sp. were inhibited by all three herbicides. There is need for moderation in the use of the current available herbicides while further research is advocated towards producing more ecofriendly herbicides.

Synthesis of Cyclopeptides Analogues of Natural Products and Evaluation as Herbicides and Inhibitors of Cyanobacteria.

Natural products derived from plants or microorganisms have been considered as eco-friendly herbicides with application in crop protection. Several natural cyclopeptides have been reported as herbicides, while others have been identified as inhibitors of cyanobacteria. In this work, the syntheses of cyclotetrapeptides and cyclopentapeptides analogues of natural products were successfully performed by solid-phase peptide synthesis of their linear precursor and solution-phase macrolactamization. Four of the obtained peptides and cyclopeptides present phytotoxicity with more than 70% of radicle growth inhibition at 67 μg/mL. In addition, evaluation of 20 peptides and cyclopeptides, as inhibitors of cyanobacteria, rendered five active compounds that reduced the concentration of microcystins in the culture medium.

Effect of Euphorbia hirta Leaf and Root Extracts on the Early Growth of Cucurbit Crops

The research investigates the allelopathic influence of Euphorbia hirta extracts on the germination and seedling development of various cucurbit species, including Bottle gourd (Sp. A), Winter melon (Sp. B), Ridged gourd (Sp. C), Sponge gourd (Sp. D), Bitter gourd (Sp. E), Snake gourd (Sp. F), Muskmelon (Sp. G), and Pumpkin (Sp. H). The experimental design incorporated the use of both aqueous and methanol extracts of E. hirta, applied at different concentrations, with distilled water employed as the control. The findings reveal that the methanolic extract of E. hirta significantly impedes both the germination process and the subsequent growth of seedlings for all cucurbit species tested. For instance, at 12 days post-treatment, control groups exhibited high germination percentages (78%, 90.67%, 95.33% and 90% for Sp. A, Sp. C, Sp. D and Sp. E, respectively), which drastically declined with a 20% methanol extract concentration (23.33%, 18.33%, and 17.67% and 18.33% for the same species, respectively). Similarly, shoot and root length measurements indicated that higher concentrations of both extracts suppressed growth, with methanol extract showing a stronger inhibitory effect compared to the aqueous extract. Interestingly, Lower extract concentrations occasionally boosted shoot growth, revealing a hormetic effect. This two-fold response, notably in Pumpkin and Snake Gourd, illuminates the complexity of allelopathic interactions. The study suggests E. hirta extracts could serve as eco-friendly herbicides, urging further research to isolate their active components. This could lessen synthetic herbicide use, promoting sustainable agriculture and environmental protection.

Diversity and dose-dependent allelopathic potential of volatile sesquiterpenes from root extracts of Chrysanthemum morifolium cultivars

Chrysanthemum × morifolium Ramat. (chrysanthemum) is rich in terpenoids in both aboveground and belowground parts with multiple biological functions. This study aims to comprehensively assess the diversity of root-derived terpenoids and their potential role in plant-plant interaction in chrysanthemums. By GC–MS identification, we revealed the intraspecific variation of terpenoid components dominated by sesquiterpenes in the root extracts among 26 chrysanthemum cultivars with different application types (including cut-flower, ground-cover and tea cultivars). The total terpenoid content in tea cultivars was generally higher than that in ground-cover and cut-flower cultivars. In this context, the correlation between the terpenoids from root extracts and allelopathic effect was established. The root extract of tea, cut-flower and ground-cover cultivars could universally promote the root length of Lactuca sativa seedling without significant effect on bud length. Moreover, the root extracts of tea and cut-flower cultivars showed no significant effects on the bud length and root length of Echinochloa crus-galli seedlings, whereas the root extract of ground-cover cultivars could significantly promote the bud length and inhibit the root length of E. crus-galli seedlings. OPLS analysis successfully correlated the content of sesquiterpenes (β-farnesene, β-elemene, β-bisabolene, neollocimene, β-sesquiphellandrene and α-longipinene) with bud and root length of L. sativa and E. crus-galli seedlings. Additionally, root extracts of 3 representative cultivars in each application type displayed dose-dependent effect in the seed germination of L. sativa. These findings provide a scientific basis for the development of eco-friendly herbicides\\plant growth regulator and the arrangement of reasonable farming systems in chrysanthemum.

The potential of invasive species Praxelis clematidea extract as a bioherbicide for Asystasia gangetica

Abstract. Wardini TH, Afifa IN, Esyanti RR, Astutiningsih NT, Pujisiswanto AH. 2023. The potential of invasive species Praxelis clematidea extract as a bioherbicide for Asystasia gangetica. Biodiversitas 24: 4738-4746. The occurrence of weeds in agriculture directly impacts crop productivity, and the reliance on synthetic herbicides to solve the problem has raised concerns about the increasing environmental damage. Using bioherbicides to control weeds is necessary to reduce the negative impact of synthetic herbicides. Bioactive compounds derived from plants can be utilized to develop eco-friendly herbicides. Praxelis clematidea extract was reported to exhibit allelopathic activity against weeds. This study aims to evaluate the potential of P. clematidea extract as a bioherbicide to control seed germination and seedling growth of Asystasia gangetica weed. P. clematidea water extract was screened for its chemical compounds and determined its phytotoxic effects on Asystasia gangetica. The results showed that P. clematidea water extract contained phenolics, alkaloids, and terpenoids. P. clematidea extract suppressed seed germination, the time needed for seed germination, sprout length, number of leaves, biomass, and total chlorophyll contents. LC50values for the seed germination, seedling, root, and shoot growth were calculated at 9%, 25%, 11%,and 37% (v/v), respectively. Thus, P. clematidea could be used as an A. gangetica weed biocontrol agent and might be integrated into weed management programs.

Investigating the phytotoxic potential of Carlina acaulis essential oil against the weed Bidens pilosa through a physiological and metabolomic approach

Essential oils (EOs) are widely studied as possible candidates for new eco-friendly herbicides for weed management due to their phytotoxicity. In this study we tested the phytotoxic potential of the EO obtained from the roots of Carlina acaulis L. (Apiaceae) against the weed Bidens pilosa L. This EO, containing 98% of the polyacetylene carlina oxide, showed strong phytotoxic effects on the plant metabolism, such as leaf necrosis, reduction of relative water content and total leaf area, and an increase in the dry weight/fresh weight ratio, suggesting a water status alteration. The EO also damaged the photosynthetic machinery, as evidenced by the significant reduction of the effective quantum yield of photosystem II (ΦII) and the maximum quantum yield of photosystem II (Fv/Fm). In addition, the non-photochemical quenching (ΦNPQ) significantly increased after spraying with C. acaulis EO. Damage to photosystem II was further demonstrated through the reduction of manganese and calcium concentrations, possibly due to an alteration in the correct functionality of the Mn4Ca cluster of the PSII. Metabolomics analysis revealed an accumulation of branched-chain amino acids, such as isoleucine and valine, which is commonly related to osmotic alterations under drought stress situations and a general reduction in sugar content (fructose, glucose, mannose, among others), suggesting reduction of the photosynthetic efficiency too. Overall, these findings suggest C. acaulis EO as a promising natural product with phytotoxic potential against weeds that deserves further investigation.

Isolation of herbicidal compounds, quercetin and β-caryophyllene, from Digera muricata

Synthetic herbicides are available to control weeds but these herbicides have many concerns. Eco-friendly herbicides obtained from plants is a better alternative to synthetic ones. Despite that the herbicidal activity of Digera muricata extracts have been reported but there are no studies regarding the isolation and identification of herbicidal compounds from D. muricata. Herein, we are reporting the identification of two herbicidal compounds from chloroform extract obtained from D. muricata. The chloroform extract was initially tested on the germination and early growth of two weeds; Avena fatua and Melilotus indicus as well as wheat where a significant decline in % age germination and growth of both weeds was observed. Among the 8 different fractions obtained using different chromatographic techniques, fractions 2 and 7 were found to be phytotoxic to both test weeds. The herbicidal efficacy was tested at 200, 150, 100, 50, 25 μg/ml. These two fractions were further purified on Reversed Phase High Pressure Liquid Chromatography (RP-HPLC). Fraction 2 yielded 3 sub-fractions (2A, 2B & 2C), while fraction 7 yielded 2 sub-fractions (7A, 7B). Fraction 2B caused 43%, 53%, and 57% decline in seed germination, shoot dry weight, and root dry weight of A. fatua, while these values against M. indicus were 50%, 81% and 84%, respectively. Fraction 7A caused 25%, 36%, and 42% decline in seed germination, shoot dry weight, and root dry weight of A. fatua, while these values against M. indicus were 35%, 62% and 69%, respectively, at 200 μg/ml conc. Cyanazine caused 61% and 50% reduction in seed germination of A. fatua and M. indicus, respectively. The herbicidal effects of these two fractions were found nonsignificant against wheat. Fourier Transform Infrared Spectroscopy (FT-IR), elemental analysis (C,H) and Nuclear Magnetic Resonanace (NMR) analyses of these two fractions depicted the presence of quercetin (Fraction 2B) and β-caryophyllene (Fraction 7A). In post emergence bioassays, the isolated compounds caused significant decrease in the biomass of both weeds. Plasma membrane integrity assays revealed electrolyte leakage in treated leaf discs of both weeds. It was concluded that quercetin and β-caryophyllene isolated from D. muricata exhibited toxicity towards both test weeds without harming wheat.

Phytotoxic meroterpenoids with herbicidal activities from the phytopathogenic fungus Pseudopestalotiopsis theae

The fungus Pseudopestalotiopsis theae isolated from the fresh leaves of Illigera celebica, has been reported to be a pathogenic fungus that can cause gray blight on tea leaves, a disease characterized by the appearance of necrotic lesions on tea leaves. The pathogenic substances in this fungus have not been clearly identified. Considering the possible involvement of specialized metabolites in symptom appearance, a chemical investigation of specialized metabolites on P. theae was conducted, resulting in the isolation of eight meroterpenoids, including six undescribed biscognienynes G-L and two known ones (biscognienynes B and D). The structures of these new compounds were characterized by extensive NMR spectroscopic and HR-ESI-MS data, and their absolute configurations were elucidated by ECD calculations. Except for biscogniyne L, all the isolated biscognienynes showed different degrees of phytotoxicity to tea in vivo, thereby revealing for the first time the substances in P. theae that cause tea gray blight. Inspired by the fact that phytotoxins produced by pathogenic fungus are an effective resource for designing natural and safe bioherbicides, when assayed the herbicidal activity through Petri dish bioassays, biscognienynes G-J showed phytotoxic effects against seed germination and seedling growth of Setaria viridis, strongly inhibiting seed germination percentage and radicle and germ lengths of seedlings. The results of this study demonstrated the great potential of biscognienynes G-J to be proposed and developed as ecofriendly herbicides.

Efficacy of Sterculia diversifolia Leaf Extracts: Volatile Compounds, Antioxidant and Anti-Inflammatory Activity, and Green Synthesis of Potential Antibacterial Silver Nanoparticles.

Sterculia diversifolia, widely distributed in Jordan as an ornamental plant, is a synonoum for Brachychiton populneus. Phytochemical studies examining the volatile chemicals in Sterculia diversifolia leaves are limited, despite the rising demand for their numerous applications. Furthermore, it was only recently that a report described the friendly synthesis of silver nanoparticles (AgNPs) using aqueous extract derived from Brachychiton populneus leaves. Therefore, AgNPs were produced using either aqueous plant extracts (AgWPE) or ethanolic plant extracts (AgEPE), and Shimadzu GC-MS equipment was used to detect volatile compounds in the ethanolic leaf extracts. GC-MS profile of leaf ethanolic extracts of the Jordanian chemotypes of S. diversifolia revealed the existence of major components: (3β)-Lup-20(29)-en-3-ol acetate (30.97%) and 1-octadecyne (24.88). Other compounds are squalene (7.19%), germanicol (6.23), dl-α-tocopherol (5.24), heptacosane (4.41), phytol (3.54) and pentacosane (2.89). According to published studies, these reported chemicals have numerous uses, including as animal feed, vitamin precursors, possible eco-friendly herbicides, antioxidants, and anti-inflammatory agents. Aqueous extracts of S. diversifolia leaves had total phenolic of 5.33 mg GAE/g extract and flavonoid contents of 64.88 mg QE/g extract, respectively. The results indicated the contribution of phenolic and flavonoids to this plant’s anti-inflammatory and antioxidant properties. The reduction in AgNO3 to AgNPs using S. diversifolia leaf extracts was confirmed by the change in solution color from colorless to dark black. Further characterization was attempted by X-ray diffraction, Malvern zeta-sizer and scanning electron microscope. The efficacy of synthesized Ag nanoparticles using aqueous or ethanolic plant extract of S. diversifolia against the Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus showed appreciable activity at 25 µg/mL concentration compared to the source plant extracts.

New α-pyrone derivatives with herbicidal activity from the endophytic fungus Alternaria brassicicola

Three pairs of undescribed enantiomeric α-pyrone derivatives (1a/1b–3a/3b) and six undescribed congeners (4–9), were obtained from the fungus Alternaria brassicicola that was isolated from the fresh leaves of Siegesbeckia pubescens Makino (Compositae). The structures of these new compounds were characterized by extensive NMR spectroscopic and HRESIMS data, and their absolute configurations were further elucidated by a modified Mosher's method, chemical conversion, single-crystal X-ray diffraction analysis, and ECD calculations. This is the first report of three pairs of enantiomeric α-pyrone derivatives from the fungus A. brassicicola, and these enantiomers were successfully acquired from scalemic mixtures via chiral HPLC. Compounds 1a/1b–3a/3b and 4–9 were evaluated for the herbicidal activity against Echinochloa crusgalli, Setaria viridis, Portulaca oleracea, and Taraxacum mongolicum. At a concentration of 100 μg/mL, compounds 1a and 1b could significantly inhibit the germination of monocotyledon weed seeds (E. crusgalli and S. viridis) with inhibitory ratios ranging from 68.6 ± 6.4% to 84.2 ± 5.1%, which was equivalent to that of the positive control (glyphosate). The potential structure-herbicidal activity relationship of these compounds was also discussed. To a certain extent, the results of this study will attract great interest for the potential practical application of promising fungal metabolites, α-pyrone derivatives, as ecofriendly herbicides.

Ag2O/BaFe12O19 nanoheterojunctions for rapid photoelimination of atrazine herbicide in water under visible light

The progress in ceramic oxide photocatalysts is a central issue in the environmental remediation of herbicides in water. Atrazine (ATZ) is a potential herbicide applied in different cultivation and food-based manufacturing processes. This paper introduces a solution-based route to synthesize barium hexaferrite (BhF) nanostructures. Formerly, trace amounts (0.4–2.0 wt%) of silver oxide (Ag2O) were deposited on BhF to produce Ag2O/BhF nanoheterojunctions. Characterization of the produced materials significantly introduced Ag2O to the BhF photoactivity without altering the main structural or surface properties. The 1.2 wt%-added Ag2O/BhF favored light harvesting and reduced the bandgap to 1.56 eV. The dose optimization (0.8 L–1) of Ag2O/BhF exhibited rapid photoelimination of ATZ in 40 min with exceptional stability after five cycles. The photocatalytic competence enhancement of Ag2O/BhF is regarded as the efficient separation of photogenerated carriers by p-n nanojunction construction. This work presents the application of nanoheterojunction oxides for eco-friendly herbicide remediation.

Allelopathic potential of Malaysian invasive weed species to control weedy rice (Oryza sativa f. spontanea Roshev)

In laboratory bioassay, we studied the effects of methanolic extracts of 30-Malaysian invasive weed species (9 families) on the seeds survival rate and seedlings growth of Weedy rice (Oryza sativa f. spontanea Roshev). Five concentrations [6.25, 12.5, 25, 50, 100 (g L-1)] of methanolic extracts were used and control was distilled water. The Weedy rice seeds survival rate and seedlings growth (radicle and hypocotyl length) of 7-day-old seedlings were reduced by the increasing concentrations of extracts than control. Probit analysis and the concentrations required for 50% inhibition (EC50) showed that radicle growth was more suppressed than seeds survival rate and hypocotyl growth. Among the tested weed species, Parthenium hysterophorus L., Cleome rutidosperma DC. and Borrreria alata (Aubl.) DC. proved strongly allelopathic and thus, could be used to develop eco-friendly herbicides.

Mentha pulegium L.: A Plant Underestimated for Its Toxicity to Be Recovered from the Perspective of the Circular Economy.

The aim of the study was to investigate the micromorphology of Mentha pulegium leaves and flowers harvested in three different Sicilian (Italy) areas with peculiar pedo-climatic conditions, and to characterize the phytochemical profile, the phytotoxic activity, and the eco-compatibility of their essential oils (EOs) for potential use as safe bioherbicides. Light microscopy (LM) and scanning electron microscopy (SEM) highlighted that M. pulegium indumentum consists of non-glandular and glandular trichomes of different types. Peltate trichomes of plants from the different sites showed few significant differences in dimension and abundance, but they were characterized by a surprisingly high number of secretory cells both in leaves and flowers. Phytochemical analyses showed that oxygenated monoterpenes were the most abundant class in all the EOs investigated (92.2–97.7%), but two different chemotypes, pulegone/isomenthone and piperitone/isomenthone, were found. The complex of morphological and phytochemical data indicates that soil salinity strongly affects the expression of the toxic metabolite pulegone, rather than the EO yield. Phytotoxicity tests showed a moderate activity of EOs against the selected species as confirmed by α-amylase assay. Moreover, the low toxicity on brine shrimp provided a rationale for the possible use of investigated EOs as eco-friendly herbicides.

Efficient synthesis and characterization of non-toxic glyphosate derivatives as eco-friendly herbicides

The present work was designed to synthesize a chain of ester derivatives of glyphosate along with their structure analysis using FTIR, 1H NMR, 31PNMR, and mass spectroscopy. Further, their herbicidal, anti-microbial and toxicological studies were carried out, and the obtained results confirmed good herbicidal effects of these derivatives on the common weed Parthenium hysterophorus. Moreover, these derivatives were also able to reduce the chlorophyll content of weeds, and their results were statistically evaluated using one-way ANOVA. In order to investigate the impact of ester derivatives on Eisenia fetida, toxicity evaluation was performed, and interestingly these derivatives were proved to be non-toxic. Additionally, the synthesized derivatives of glyphosate were found to be less polar in contrast to their parent molecule. They were easily degraded by soil bacteria and undeniably may prove beneficial in curbing the problem of their leaching into the water bodies and soil ecosystems.

Assessment of allelopathic compounds to develop new natural herbicides : A review

Herbicides are a crucial tool for weed control in crops. However, their continuous and indiscriminate uses have caused environmental pollution and development of weed resistance. Hence, there is an urgent need to minimise the dependence on synthetic herbicides. Allelopathy may be used to develop new bioherbicides to inhibit germination and growth of weeds. There is a great potential to develop eco-friendly herbicides from plants, but little research has been done so far in this context. Identification and quantification of natural weed control compounds (allelochemicals) of plants may help to develop natural herbicides (based on indigenous/invasive weed species), to reduce the dependence on synthetic herbicides and improve the integrated weed management programme in crops. This review describes thepotential allelochemicals present in plants, which may be used as a tool to develop new natural herbicides.

Yield, quality and weed control in soybean crop as affected by several cultural and weed management practices

In the field of Agricultural University of Athens, the effects of false seedbed technique, stale seedbed, chemical and ecologically based control on weed growth and soybean yield were evaluated (2019). The experimental treatments were: normal seedbed, normal seedbed along with pre-emergence chemical control, false seedbed, stale seedbed with glyphosate and stale seedbed with pelargonic acid. In the plots of normal seedbed along with pre-emergence chemical control, pendimethalin was applied at rate of 1560 g a.i. ha-1. In the plots of stale seedbed with glyphosate, glyphosate was applied at a rate of 2160 g a.e. ha-1 and in the plots of stale seedbed with pelargonic acid, pelargonic acid was applied at a rate of 31020 g a.i. ha-1. The experiment was conducted in a randomized complete block design with three replicates. The results revealed that stale seedbed combined either with glyphosate or pelargonic acid application reduced annual weeds’ density by 94 and 95% as compared to normal seedbed. Stale seedbed along with pelargonic acid reduced the density of perennial weeds by 36, 38 and 41% as compared to the combination of normal seedbed and pre-emergence chemical control, normal seedbed and false seedbed, respectively. The application of glyphosate in stale seedbed plots was also effective against perennial weeds. It was also observed that stale seedbed along with glyphosate increased soybean seed yield by 17, 19 and 35% as compared to the combination of normal seedbed and pendimethalin application, false seedbed and normal seedbed, respectively. Beneficial were also the effects of the combination of stale seedbed and pelargonic acid not only on soybean seed yield but also on soybean protein content. Further research is needed in order to investigate the role of false and stale seedbeds as integrated weed management practices in various crops and under different soil and climatic conditions. Research is also needed to evaluate pelargonic acid for weed control in stale seedbeds since it is an eco-friendly herbicide with no restrictions for organic farming.

Aplikasi Herbisida Ramah Lingkungan di Desa Kiusili Kecamatan Bikomi Selatan Kabupaten Timor Tengah Utara

Telah dilakukan pengabdian pada masyarakat di kelompok tani Nek’amnaut Desa Kiusili kabupaten Timor Tengah Utara. Pengabdian berupa penggunaan herbisida ramah lingkungan yang terbuat dari garam, cuka, air dan sabun cair. Metode pengabdian berupa sosialisasi dan demo pembuatan serta penyermprotan larutan tersebut pada gulma. Pengisian quisioner pra pengabdian dan pasca pengabdian dilakukan guna mengetahui pengetahuan terkait herbisida pada umumnya dan kemampuan masyarakat membuat herbisida ramah lingkungan.
 Hasil menunjukkan bahwa larutan herbisida ramah lingkungan berhasil membunuh gulma. Pengetahuan masyarakat berubah dari kategori tidak tahu menjadi berpengetahuan baik, ditandai peningkatan skor pengetahuan (SP) dari 24 menjadi 76. Presentase jumlah warga yang mengalami perubahan kategori ini adalah 0 menjadi 83%. Kemampuan masyarakat berubah dari tidak mampu membuat menjadi sangat mampu membuat herbisida tersebut, ditandai skor kemampuan (SK) meningkat dari 0 menjadi 83. Presentase jumlah masyarakat yang mengalami perubahan kategori kemampuan adalah dari 0 menjadi 89%. Penurunan intensitas penggunaan herbisida sintetik terjadi dalam tiga tahun terakhir. Sebanyak 5 liter larutan herbisida ramah lingkungan mampu membunuh gulma seluas 48 m2.

English

Herbicide resistance and environmental pollution are the risks associated with chemical control of weeds. Allelopathic plant extracts may be exploited for weed management as an alternative to commercial herbicides. Before development of allelochemical-based eco-friendly herbicides, bioherbicidal potential of plants need to be evaluated. Present study was conducted to evaluate phytotoxic allelopathic impact of leaf extract from eight agroforestry and fruit plant species against Lepidium sativum. The results showed that all plant species delayed germination and inhibited root length, shoot length and seedling dry weight of Lepidium sativum. Four plant species such as Moringa oleifera, Mangifera indica, Albizia procera and Delonix regia were most phytotoxic with Lepidium sativum root growth inhibition of ≥85% as compared with control and seedling persistence index <30% of control. Phenolic contents were maximum in Mangifera indica (137 mg g-1 leaf dry weight) followed by Delonix regia (130 mg g-1 leaf dry weight). The results suggest that phytotoxic action of leaf extract of plant species may be due to presence of phenolic allelochemicals that may be exploited further either directly for weed management or development of bioherbicides.

Mesotrione herbicide does not cause genotoxicity, but modulates the genotoxic effects of Atrazine when assessed in mixture using a plant test system (Allium cepa)

Mesotrione (MES) is an herbicide from the triketone family and has been used as an alternative to Atrazine (ATZ), which was banned in some countries due to its toxicity to non-target organisms. Despite being considered an eco-friendly herbicide, data from the literature about the harmful effects of MES in its pure form and/or in combination with other herbicides is still scarce. Aimed at assessing the potential of MES to induce cell death and DNA damage, seeds of Allium cepa (higher plant, monocotyledon) were exposed to this herbicide, pure and in mixture with ATZ, and the number of dividing cells (cytotoxicity), chromosomal aberrations (CA, genotoxicity) and micronuclei (MN, mutagenicity) were then quantified. The pure MES (1.8 to 460 μg/L) did not show either cytotoxicity or genotoxicity/mutagenicity under the tested conditions. The genotoxicity of ATZ (1.5 to 400 μg/L), previous reported in the literature, was confirmed herein. The assessment of MES + ATZ mixtures (1.8 + 1.5; 7 + 6.25; 30 + 25 μg/L, respectively) showed that MES, at low concentrations, enhance the genotoxicity of ATZ (potentiation), since the significant frequencies of CA and MN were greater than the ones expected in additive effects. Taking together, MES in its pure form seems to be a safe alternative to ATZ regarding the capacity to damage (at cellular and DNA levels) non-target plants (Monocots); however, MES in combination with ATZ appeared to act as a co-mutagen at low concentrations.

ISOLATION AND CHARACTERIZATION OF NATURAL HERBICIDAL COMPOUND FROM Drechslera rostrata

ABSTRACT In agriculture, weeds have inevitable importance because of reducing the crop growth and also affecting food quality. Although, synthetic herbicides are available to combat these weeds but during recent years there is a trend of using ecofriendly herbicides extracted from natural resources. Present investigation is a continuity of the research, which reported a natural herbicidal compound named as Ophiobolin A from a fungus, Drechslera rostrata. The fungus was incubated in a growth medium of known composition (minimal medium) up to 28 days and its metabolites were extracted with organic solvents. The compound showing bioactivity was purified with the help of Reversed Phase High Performance Liquid Chromatography (RPHPLC) and identified with the help of Spectroscopic techniques viz. Mass Spectroscopy (MS) (LRESIMS and HRESIMS) and Nuclear Magnetic Resonance Spectroscopy (NMR). The purified compound caused death of superficial leaf cells of Chenopodium album, a noxious weed of wheat. Present investigation concludes that the identified compound could be used as structural analogue alternative to synthetic herbicides to synthesize natural herbicides.