Search

A field experiment was done with little millet variety 'Samai ATL-1' and treated with 6-leaf extracts and 1 flower extracts [(Tamarind (Tamarindus indica L.), Casuarina (Casuarina equisetifoliaL.), Castor (Ricinus communis L.), Papaya (Carica papaya L.), Pine (Pinus sylvestris L.)], Teak (Tectona grandis L.) and Nerium (Nerium oleander L.) flowers)] of 30 % concentration. The highest weed control efficiency and lowest weed index was recorded in Teak leaf of 30 % (52 % and 10 %) followed by Castor leaf extract 30 % (52 % and 12 %) and Papaya leaf extract 30 % (50 % and 14 %) at 60 DAS. The soil microbial population did not show any harmful effects of leaf extracts. The pre-emergence application of 30 % teak leaf extract considerably reduced the weed density and weed dry weight below the economic threshold level. Secondary metabolites inhibiting the weeds were identified through Gas Chromatography and Mass Spectrometry (GC-MS) analysis, which identified significant compounds such as Gallic acid and Diethyl phthalate in teak, Ricinine and l-(+)-Ascorbic acid 2,6-dihexadecanoate in castor, and Vannilic acid and Squalene in papaya. These compounds may be associated with the observed decrease in the dry weight of weeds. [ABSTRACT FROM AUTHOR]

The use of allelopathy developed as an alternative practice for weed management in agriculture. Oldenlandia corymbosa is an annual herb and notable for being applied in folk medicine. Its diverse range of pharmacological properties and several bioactive substances have been well reported. Nevertheless, the allelopathic potential of O. corymbosa has not yet been documented. Hence, we aim to explore the allelopathy of O. corymbosa for weed control purposes. The extracts of O. corymbosa were tested to determine their effects on the seedling growth of six tested species. Significant reductions in the growth of seedling were exhibited as the plant extract concentrations increased. The plant extracts of O. corymbosa were separated in several chromatography steps; two active substances isolated and characterized as hedyotiscone A and B. Hedyotiscone A and B significantly restricted the growth of cress seedling at concentrations higher than 0.3 mM. The I50 values of hedyotiscone A and B for the cress seedlings ranged from 0.023 to 0.131 mM and 0.167 to 0.810 mM, respectively. The inhibitory activity against cress seedlings indicates that hedyotiscone A and B contribute to the allelopathic effects and may be responsible for the allelopathic potential of O. corymbosa. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the allelopathic potential of Crotalaria spp. to control guinea grass (Panicum maximum Jacq.). Experiments were done on germination and development of P. maximum in Petri-plate Lab Bioassays with the seed exudates of germinating seeds germination water of seed and leaf extract of C. juncea and also in Pot Culture coexistence by sowing and transplantation of two test species. Among the species studied, C. juncea gave the best result to inhibit the germination of target plant, hence, it was selected for further studies. The germination results showed that the highest densities (5, 10 and 20) of C. juncea affect different stages of P. maximum. The higher the concentration of bioextract from C. juncea, the lower was development of P. maximum was decreased with doses from 25 to 100 % for its control. The greater was the density and concentration of C. juncea extracts, the greater was the decrease in germination speed, germination (%), root length, plant height and dry mass weight of P. maximum. [ABSTRACT FROM AUTHOR]

When facilitating other species and sustaining plant community structures and biodiversity, alpine cushion plants simultaneously experience negative feedback effects from surrounding vegetation. However, the impact of surrounding vegetation on cushion dynamics remains poorly understood, particularly in terms of allelopathic potentials. To investigate the allelopathic potentials of surrounding vegetation on seedling establishment of the typical cushion plant Arenaria polytrichoides Edgew. along an elevational gradient, we extracted potential allelopathic compounds and tested their impacts on seed germination and seedling growth of A. polytrichoides. In addition, exclusion experiments using activated carbon were conducted to further elucidate these effects. Our results demonstrate that surrounding vegetation exhibits certain allelopathic potentials on A. polytrichoides seedling establishment, with variations observed based on elevation, source and concentration of allelopathy compounds, as well as growing season. Specifically, low-elevation vegetation exerts pronounced suppression on seedling establishment. Conversely, higher-elevation vegetation generally shows no effect on seed germination but stimulates seedling growth through allelopathy mechanisms. Moreover, aboveground vegetation predominantly inhibits both seed germination and seedling growth in low-elevation communities; however, the effects of belowground vegetation depend on elevation and extract concentration levels. The identified allelopathic potentials of surrounding vegetation significantly influence the population dynamics of cushion A. polytrichoides by potentially accelerating population degeneration in lower-elevation communities while ensuring consistent population recruitment and expansion in higher-elevation communities. [ABSTRACT FROM AUTHOR]

An experiment was conducted to evaluate the allelopathic effect of aqueous extract of different parts of Eucalyptus on the germination characteristics and seedling growth of the benchmark plant and sensitive to allelochemicals of chickpea in both laboratory and greenhouse conditions in a completely randomized design with three replications, separately. At first, the dried samples were powdered by a mill. To extract the samples in the laboratory condition, first 2 g of the powdered plant organs of leaf and bark along mixture of them (weight) was extracted separately with 100 ml of distilled water as solvent (volume), separately. Then different concentrations (0 (control), 5, 15, and 20%) were prepared from the extract obtained from the stock (base solution). In greenhouse condition, different amounts of plant residues (i.e. .5, 1, 2, and 5 g of dry material in 3 kg of loam soil) of each organ, and their mixture were prepared in pots, separately. The pots were kept for 60 days in order to rot and the activity of microorganisms in these conditions. Finally, for bioassay experiment, some characteristics of germination percentage, radicle and shoot length, allometric coefficient, seed vigor index, and in the case of greenhouse experiment, germination percentage, plant length, seedling fresh and dry weight were measured. According to the results, the effect of Eucalyptus organs, different concentrations or amounts of plant residues, and their interaction effect on the characteristics of germination and seedling growth of chickpeas were significant (p<0.05). The intensity of the inhibitory or stimulating effect of the aqueous extract of organs and their mixture on chickpea seeds was dependent on the type of organ and the concentration of the aqueous extract or the amount of decayed Eucalyptus residues. In most cases, the leaf organ had the greatest inhibitory effect on the characteristics of chickpea germination and seedling growth. Therefore, due to the high biomass of the Eucalyptus plant and its high ability of hetrotoxicity, it can be considered as a candidate for the production of herbicides to reduce the spread of weeds in organic farming systems. [ABSTRACT FROM AUTHOR]

The purpose of this study was to obtain additional value of hydrolates (HYs), by-products during essential oil distillation. Chemical compositions of angelica and hop hydrolates were determined and compared with the corresponding essential oils, and their biological potential tested. Steam distilled essential oils and hydrolates were analyzed by GC-MS, and their biological potential was tested for antioxidant (DPPH, ABTS and reduction power) and antimicrobial activities (against nine bacteria and fungi). Hydrolates were additionally tested for allelopathic activity (on corn and redroot pigweed). The investigated essential oils have totally different volatile profiles and aromas in comparison to hydrolates. The most dominant constituents in the angelica essential oil were limonene, β-phellandrene, α-pinene, α-phellandrene and δ-3-carene, while in the hydrolate it was trans-verbenol. In the hop essential oil the most dominant constituents were myrcene and α-humulene, while in the hydrolate isovaleric acid and linalool were dominant. Angelica essential oil showed higher antioxidant activity in comparison with hop, while hydrolates displayed significantly lower antioxidant activity. Low antimicrobial potential of both essential oils was observed in the case of Enterococcus faecalis, Escherichia coli, Saccharomyces cerevisiae and Candida albicans. Antimicrobial activity was not detected in neither of the two hydrolates. In terms of allelopathic activity, hydrolates showed a dose-dependent decreasing activity on germination and seedling growth of corn and redroot pigweed. Angelica and hop essential oils are mainly used in food, cosmetic and pharmaceutical industries because of their aroma. Hydrolates, as by-products, possess potential for application in agriculture as natural herbicides. [ABSTRACT FROM AUTHOR]

An experiment was conducted in order to evaluate the allelopathic effect of water extract from different parts of Eucalyptus on the germination characteristics and seedling growth of the benchmark plant and sensitive to allelochemicals of chickpea in both laboratory and greenhouse conditions in a completely randomized design with three replications, separately. At first, the dried samples were powdered by a mill. For bioassay experiment, a 2% suspension of Eucalyptus leaves and bark along mixture of them was prepared, and then different dilutions of the suspension such as 0 (control), 5, 15 and 20% of the resulting suspension were applied. In greenhouse condition, different amounts of plant residues including 0.5, 1, 2, and 5% by weight of each leaf organ, bark, and their mixture were prepared separately in three kg of loam soil in pots. The pots were kept for 60 days in order to rot and the activity of microorganisms in these conditions. Finally, for bioassay experiment, some characteristics of germination percentage, radicle and shoot length, allometric coefficient, seed vigor index, and in the case of greenhouse experiment, germination percentage, plant length, seedling fresh and dry weight were measured. According to the results, the effect of Eucalyptus organs, different concentrations or amounts of plant residues, and their interaction effect on the characteristics of germination and seedling growth of chickpeas were significant (p

• Cell cycle delay associated with Commelina benghalensis in plant species. • Chemical composition of the leaf extract of Commelina benghalensis , exotic species. • Morphoanatomical Changes associated with the leaf extract of Commelina benghalensis. • Cytotoxicity and genotoxicity of Commelina benghalensis leaf extract. The objective of this work was to verify the phytotoxic action of the aqueous extract of Commelina benghalensis , on the initial development of Lonchocarpus sericeus. The parameters analyzed were germination, Germination Speed Index (GVI), average length of the stem and radicle, morphoanatomical alterations, cytotoxic activity and phytochemical characterization of the donor species. The 100 % extract was prepared by grinding 250 g of fresh leaves of the donor species in 1 L of distilled water and diluted to 25 %, 50 %, 75 % concentration (Treatments), the control group 0 %, consisted of distilled water only. The bioassays were placed in a germination chamber of the type BOD (Biochemical Oxygen Demand) climate-controlled chambers with a constant temperature of 25 °C and a 12 h photoperiod (light/dark). The extract of C. benghalensis at 75 % and 100 % concentration promoted a negative phytotoxic action on the average length of the rootlets of L. sericeus. The length of the stems showed a reduction only at the 100 % concentration. A significant increase in the genotoxic effect of the extract at 75 and 100 % concentration was observed, with the presence of chromosomal bridges, chromosomal adhesion, chromosome loss, C-metaphase and absence of membrane. The treatments caused changes in the internal morphology of the plant tissues of the radicle, such as necrosis of the epidermis and vascular system and disorganization of the cortex tissues. The allelochemicals present in the extract of C. benghalensis , such as alkaloids, anthocyanins, anthocyanidins, chalcones, aurones, flavonones, flavonols, xanthones, catechins, flavonones, were probably responsible for the negative effect found on the mitotic index and on the development and organization from the radicle tissues of L. sericeus. [ABSTRACT FROM AUTHOR]

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

The aim of the present work is to study the chemical composition, to estimate the phenolic compounds content and to evaluate the potential allelopathic effects of the Haloxylon scoparium Pomel. Phytochemical tests revealed that Haloxylon scoparium contains tannins, saponins, coumarins, alkaloids, flavonoids and steroids. Furthermore, it contains high levels of total phenolic (588.33 mg GAE 100 g-1) and flavonoids (95.45 mg QE 100 g-1) contents. Moreover, LC-MS-MS analysis allowed us to determine their chemical composition. The results of this characterization confirm the presence of vanillin, naringenin, folic acid, maleic acid, benzoic acid, myricetin, qwuercetin, beta-carotene, butylhydroxyanisole (BHA), butylated hydroxytoluene (BHT), rutin, cafeic acid, hydroxy-4-coumarine, ascorbic acid, and gallic acid. The allelopathic effect was studied on seed germination and seedling growth of four weed species. The bioassays were performed using different concentrations (1 %, 2.5 %, 5 % and 10 %) against a negative control. The seed germination, shoot and root length of weed species were completely inhibited at the highest concentrations (10 %, 5 %). However, the lower concentrations exhibited lesser inhibition percentages on the germination and the seedling growth. The phytochemical results and the significant allelopathic effects of the plant extract suggest that this species may offer new substances for the biocontrol of weeds.

Investigation of allelopathic substances from herbal plants may lead to the development of allelochemical-based natural herbicides. Croton oblongifolius (Roxb.) is a well-known herbal plant with a long history of being used for traditional medicines and for being the source of a diverse range of bioactive compounds. This plant has been reported to have allelopathic potential; however, its allelopathic-related substances have not yet been described. Therefore, we conducted this investigation to explore the allelopathic substances from the leaves of C. oblongifolius. Aqueous methanol extracts of C. oblongifolius leaves exhibited significant growth inhibitory potential against four test plants (monocot barnyard grass and timothy, and dicot cress and lettuce). The leaf extracts were purified in various chromatographic steps and yielded four active compounds identified as (3R,6R,7E)-3-hydroxy-4-7-megastigmadien-9-one (I), 2-hydroxy alpinolide (a novel compound) (II), alpinolide (III), and epialpinolide (IV) via an analysis of the spectral data. These identified compounds significantly restricted the seedling growth of cress. The concentration necessary for 50% growth reduction of the cress seedlings varied from 0.15 to 0.24 mM for (3R,6R,7E)-3-hydroxy-4-7-megastigmadien-9-one, 0.04 to 0.11 mM for 2-hydroxy alpinolide, 0.07 to 0.12 mM for alpinolide, and 0.09 to 0.16 mM for epialpinolide. Therefore, the leaf extracts of C. oblongifolius and the characterized compounds have the potential to be used as weed-suppressive resources for natural weed control. [ABSTRACT FROM AUTHOR]

Trewia nudiflora Linn. is a valuable forest resource due to its economic, ethnomedicinal, and ecological properties; however, its allelopathic potential is undocumented. Therefore, this research was designed to investigate the allelopathic impacts of T. nudiflora leaf extracts on alfalfa (Medicago sativa L.) and barnyard grass (Echinochloa crus-galli (L.) P. Beauv.) growth, as well as to isolate and to identify the active allelopathic substances responsible for these effects. A bioassay experiment with eight different treatments (0.1, 0.3, 1, 3, 10, 30, 100, and 300 mg dry weight (DW) equivalents of T. nudiflora extracts in mL−1) was carried out. The results showed that the growth of both plants decreased with increasing contents of T. nudiflora extracts, with the effect depending on the plant species and reaching its peak at a concentration of a 300 mg DW equivalent of T. nudiflora extract in mL−1. Active substances were isolated and identified using an HPLC system, which revealed the presences of methyl gallate and pinoresinol in aqueous methanol extracts of T. nudiflora. The shoot and root lengths of the alfalfa and the barnyard grass decreased significantly when they were treated with the methyl gallate and the pinoresinol. The allelopathic inhibition increased with increasing compound concentrations, with the root growth being more sensitive to the pinoresinol than to the methyl gallate, and it was significantly higher at the concentration of 10 mM. These results indicated that the T. nudiflora leaf extracts limited the growth of the treated plants, and the methyl gallate and pinoresinol in the extracts may have caused the inhibition of the T. nudiflora extracts. Thus, the leaf extracts of T. nudiflora and the substances methyl gallate and pinoresinol could be incorporated into sustainable agricultural practices or used to develop bioherbicides that would promote sustainable weed management practices. [ABSTRACT FROM AUTHOR]

Agricultural production depends heavily on the application of synthetic herbicides. Using these herbicides results in the development of herbicide-resistant weeds, poses hazards to human and animal health, and pollutes the environment. To solve these problems, developing and using bioherbicides must be increased. Although different uses of Albizia procera have been well reported, its allelopathic activity against weeds and crop species has not. Hence, we evaluated the allelopathic activity of the A. procera plant and isolated its allelopathic compounds. Extracts of A. procera significantly suppressed the seedling growth of the tested species (cabbage, alfalfa, lettuce, barnyard grass, timothy, and Italian ryegrass). The seedling growth decreased with increasing extract concentrations. The concentrations required for 50% growth inhibition (I50 value) of the tested plants were 0.0225–0.4935 mg/mL. The A. procera extracts were separated using different column chromatography, and two active fractions (AP-5 and AP-7) were isolated. Cress seedling growth was completely restricted by fraction AP-5, and fraction AP-7 restricted the cress shoots to 83.10% and roots to 85.65% of the control treatment. The findings of this study indicate that A. procera extracts have allelopathic activity and these fractions might contribute to the activity.

Pinto peanut (Arachis pintoi Krapov. & W.C. Greg.) is an herbaceous perennial plant which belongs to the Leguminosae family. This plant is well known for its use as a cover crop, but little information is available on the allelopathic potential of this legume. Therefore, this study aimed to explore the allelopathic effects of A. pintoi under various screening conditions and to analyze its potential allelochemicals using gas chromatography–mass spectrometry (GC-MS). In laboratory bioassays, aqueous extracts of A. pintoi powder exerted the average inhibition of the growth of Echinochloa crus-galli (55.1%), Oryza sativa (77.1%), and Vigna radiata (60.1%), respectively, of which the root lengths of the tested plants were the most suppressed. In greenhouse experiments, E. crus-galli was inhibited by 63.4% at 200 g/m2 of A. pintoi dried powder application. In field trials, A. pintoi also significantly reduced the growth of E. crus-galli and natural weeds. By incorporating a dose of 200 g/m2, the average inhibition of E. crus-galli was 43.9%, the dry weight of natural paddy weeds was 43.1%, and rice yield was simultaneously increased by 35%. The growth inhibitions of weeds and tested plants were proportional to the doses of A. pintoi applied and varied with the tested plant species. Among three different solvent extracts (methanol, hexane, and ethyl acetate), the hexane extract exerted the highest suppression against the growth of E. crus-galli and L. sativa by IC50 against root and shoot growth = 4.08 and 8.4 mg/mL and 1.7 and 1.54 mg/mL, respectively, followed by ethyl acetate extract, while the least effective was methanol extract. From those extracts, a total of 35 substances were detected by GC-MS analyses, including 14 newly identified constituents, such as phenolic acids, stearic acid, palmitic acid, fatty acids, pyranones, and benzofurans, which may be responsible for the herbicidal effects of A. pintoi. This study suggests that A. pintoi may be used as a source of bioherbicide to minimize the dependency on harmful synthetic herbicides and enhance rice yield. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the impact of wind and salt stress on the allelopathic potential of medicinal trees growing on Sanjiao Island. The test species were Eucalyptus urophylla Blake., Toxicodendron succedaneum (L.) Ktze., Litsea rotundifolia Hemsl. var. oblongifolia (Nees) Allen., Schefflera heptaphylla (L.) Frodin. and Rhodomyrtus tomentosa (Ait.) Hassk. They were grown in pots regularly subjected to air flows (0~2 m/s or 4~6 m/s) or irrigation with NaCl solutions at 8 % or 10 %. Similar plants without exposure to salt or air flow served as controls (CK). Aqueous extracts were prepared from these trees leaves and tested on seed germination of radish and cabbage in laboratory assays, and their total phenol/flavonoid content were measured. Exposure of E. urophylla, L. rotundifolia, and R. tomentosa to wind and/or salt stress significantly inhibited the growth of the recipient plants, while T. succedaneum had the stimulatory effects. S. heptaphylla subjected to wind stress significantly stimulated the root growth of cabbage (Brassica oleracea var. capitata L.) and radish (Raphanus sativus L.) but inhibited the shoot growth of cabbage. While the S. heptaphylla exposed to salt stress stimulated the root length and inhibited the root mass of cabbage and radish. Wind and salt stress significantly enhanced the allelopathic potential of E. urophylla and L. rotundifolia, while, reducing the allelopathic potential of T. succedaneum. Wind stress had a dominant influence on the allelopathic potential of S. heptaphylla, while, salt stress dominated R. tomentosa's influence. Phenols were detected in all five species, but flavonoids were detected only in L. rotundifolia, S. heptaphylla, and R. tomentosa. Thus wind and salt stress were important factors affecting the allelopathic potential of test plants. The enhanced allelopathic potentials of E. urophyllai and T. succedaneum could be explained by increased total phenols and/or flavonoids, while the decreased total phenols of T. succedaneum accounted for its stimulatory allelopathic potential. [ABSTRACT FROM AUTHOR]

Total releasing phenolic compounds and allelopathic potential of the three sunflower genotypes Helianthus annuus L. residues were evaluated under open field conditions on weed flora associated with the proposed crops; wheat, broad bean and flax which are cultivated usually after the sunflower crop as successive crops. After getting seed from the sunflower crop. After getting seeds, sunflower plant parts were chopped and incorporated with field soil using a rotavator. Regarding the phenolics, total phenolic compounds released from sunflower residues were increased in-field soil and reached the highest concentration in the fourth week after mixing with soil. Significant suppression of weed flora was observed when the weed density and weed dry matter were reduced. Sakha sunflower genotype had the most effect, while Ishaqi genotype had the least amount of phenolic compounds. The residue of the Sakha genotype effectively suppressed over 80% of targeted weeds. The results indicate that the allelopathic potential of sunflower residues can cause suppression of weed flora which can be useful as an attractive alternative natural way to reduce synthetic herbicides as sustainable weed management. [ABSTRACT FROM AUTHOR]

Background: Allelopathy is the process of a plant's chemical release into the environment having direct or indirect, beneficial or negative effects on another plant. In the present work, we investigated the allelopathic interaction of Acacia modesta in the different extracts to show significant effects regarding the growth and germination of test species. Objective: The main objective of this research is to study how the allelopathic activity of Acacia modesta affects the growth of three Brassica species in various extracts (Aqueous extracts, litter & mulching). Methodology: Fresh leaves of Acacia modesta were collected from the Botanical Garden, Islamia College Peshawar, dried in the shade, and ground, whereas the glass ware was rinsed and sterilized for at least 4 hours at 170°C. Seeds of the Brassica crop were used and checked for viability in H2O. The Petri dishes were incubated at 25°C for 72 hours, then the effects of various extracts were examined, and lastly, readings from the Petri dishes were obtained. Results: According to our findings, the leaf extracts of Acacia modesta had a substantial effect on the germination and growth of Brassica species. Brassica campestris (10g/48h dry & 5g/24h fresh), Brassica napus (10g/24h), and Brassica juncea (10g/48h dry & 5g/48h fresh) leaf extracts have a greater effect than the control. Conclusion: Our outcomes concluded that in comparison of the test species in all the experiments, Brassica campestris and Brassica juncea were highly affected by the allelopathy of A. modesta which necessitates further evaluation.

We evaluated the allelopathic potential of allelochemicals present in the swamp rice (Oryza sativa L.) varieties. The effects of 10-swamp rice varieties (Inpara 1, Inpara 2, Inpara 3, Inpara 4, Inpara 5, Inpara 6, Inpara 7, Inpara 8 Agritan, Inpara 9 Agritan and Inpara 10 BLB) were studied on two weeds (Echinochloa crus-galli and Monochoria vaginalis). The allelochemicals released as root exudates from these swamp rice varieties were quantified in root and soil samples with high-performance liquid chromatography (HPLC). The results showed that the swamp rice varieties differed in inhibiting the growth of E. crus-galli and M. vaginalis. The variety Inpara 7 caused maximum growth suppression of E. crus-galli (23.9 %) and M. vaginalis (29.3 %) than other varieties. Furthermore, Inpara 3, 4, 6, 7 and 8 varieties also suppressed the growth of test weeds. HPLC analysis indicated that the allelochemicals concentration was significantly higher in roots than in soil, depending on the variety. The p-hydroxybenzoic acid content in the roots was higher than ferulic and p-coumaric acids, but the release of p-coumaric acid contents into the soil was higher than other compounds. The Inpara 3 roots contained higher contents of ferulic and pcoumaric acids than other varieties, while the highest p-hydroxybenzoic content was found in Inpara 2. The ferulic and p-coumaric acids were significantly correlated with weed growth variables. These compounds may play important roles in regulating rice allelopathy. [ABSTRACT FROM AUTHOR]

Agricultural production depends heavily on the application of synthetic herbicides. Using these herbicides results in the development of herbicide-resistant weeds, poses hazards to human and animal health, and pollutes the environment. To solve these problems, developing and using bioherbicides must be increased. Although different uses of Albizia procera have been well reported, its allelopathic activity against weeds and crop species has not. Hence, we evaluated the allelopathic activity of the A. procera plant and isolated its allelopathic compounds. Extracts of A. procera significantly suppressed the seedling growth of the tested species (cabbage, alfalfa, lettuce, barnyard grass, timothy, and Italian ryegrass). The seedling growth decreased with increasing extract concentrations. The concentrations required for 50% growth inhibition (I50 value) of the tested plants were 0.0225–0.4935 mg/mL. The A. procera extracts were separated using different column chromatography, and two active fractions (AP-5 and AP-7) were isolated. Cress seedling growth was completely restricted by fraction AP-5, and fraction AP-7 restricted the cress shoots to 83.10% and roots to 85.65% of the control treatment. The findings of this study indicate that A. procera extracts have allelopathic activity and these fractions might contribute to the activity. [ABSTRACT FROM AUTHOR]

Investigation of allelopathic substances from herbal plants may lead to the development of allelochemical-based natural herbicides. Croton oblongifolius (Roxb.) is a well-known herbal plant with a long history of being used for traditional medicines and for being the source of a diverse range of bioactive compounds. This plant has been reported to have allelopathic potential; however, its allelopathic-related substances have not yet been described. Therefore, we conducted this investigation to explore the allelopathic substances from the leaves of C. oblongifolius. Aqueous methanol extracts of C. oblongifolius leaves exhibited significant growth inhibitory potential against four test plants (monocot barnyard grass and timothy, and dicot cress and lettuce). The leaf extracts were purified in various chromatographic steps and yielded four active compounds identified as (3R,6R,7E)-3-hydroxy-4-7-megastigmadien-9-one (I), 2-hydroxy alpinolide (a novel compound) (II), alpinolide (III), and epialpinolide (IV) via an analysis of the spectral data. These identified compounds significantly restricted the seedling growth of cress. The concentration necessary for 50% growth reduction of the cress seedlings varied from 0.15 to 0.24 mM for (3R,6R,7E)-3-hydroxy-4-7-megastigmadien-9-one, 0.04 to 0.11 mM for 2-hydroxy alpinolide, 0.07 to 0.12 mM for alpinolide, and 0.09 to 0.16 mM for epialpinolide. Therefore, the leaf extracts of C. oblongifolius and the characterized compounds have the potential to be used as weed-suppressive resources for natural weed control.

Trewia nudiflora Linn. is a valuable forest resource due to its economic, ethnomedicinal, and ecological properties; however, its allelopathic potential is undocumented. Therefore, this research was designed to investigate the allelopathic impacts of T. nudiflora leaf extracts on alfalfa (Medicago sativa L.) and barnyard grass (Echinochloa crus-galli (L.) P. Beauv.) growth, as well as to isolate and to identify the active allelopathic substances responsible for these effects. A bioassay experiment with eight different treatments (0.1, 0.3, 1, 3, 10, 30, 100, and 300 mg dry weight (DW) equivalents of T. nudiflora extracts in mL−1) was carried out. The results showed that the growth of both plants decreased with increasing contents of T. nudiflora extracts, with the effect depending on the plant species and reaching its peak at a concentration of a 300 mg DW equivalent of T. nudiflora extract in mL−1. Active substances were isolated and identified using an HPLC system, which revealed the presences of methyl gallate and pinoresinol in aqueous methanol extracts of T. nudiflora. The shoot and root lengths of the alfalfa and the barnyard grass decreased significantly when they were treated with the methyl gallate and the pinoresinol. The allelopathic inhibition increased with increasing compound concentrations, with the root growth being more sensitive to the pinoresinol than to the methyl gallate, and it was significantly higher at the concentration of 10 mM. These results indicated that the T. nudiflora leaf extracts limited the growth of the treated plants, and the methyl gallate and pinoresinol in the extracts may have caused the inhibition of the T. nudiflora extracts. Thus, the leaf extracts of T. nudiflora and the substances methyl gallate and pinoresinol could be incorporated into sustainable agricultural practices or used to develop bioherbicides that would promote sustainable weed management practices.

Pinto peanut (Arachis pintoi Krapov. & W.C. Greg.) is an herbaceous perennial plant which belongs to the Leguminosae family. This plant is well known for its use as a cover crop, but little information is available on the allelopathic potential of this legume. Therefore, this study aimed to explore the allelopathic effects of A. pintoi under various screening conditions and to analyze its potential allelochemicals using gas chromatography–mass spectrometry (GC-MS). In laboratory bioassays, aqueous extracts of A. pintoi powder exerted the average inhibition of the growth of Echinochloa crus-galli (55.1%), Oryza sativa (77.1%), and Vigna radiata (60.1%), respectively, of which the root lengths of the tested plants were the most suppressed. In greenhouse experiments, E. crus-galli was inhibited by 63.4% at 200 g/m2 of A. pintoi dried powder application. In field trials, A. pintoi also significantly reduced the growth of E. crus-galli and natural weeds. By incorporating a dose of 200 g/m2, the average inhibition of E. crus-galli was 43.9%, the dry weight of natural paddy weeds was 43.1%, and rice yield was simultaneously increased by 35%. The growth inhibitions of weeds and tested plants were proportional to the doses of A. pintoi applied and varied with the tested plant species. Among three different solvent extracts (methanol, hexane, and ethyl acetate), the hexane extract exerted the highest suppression against the growth of E. crus-galli and L. sativa by IC50 against root and shoot growth = 4.08 and 8.4 mg/mL and 1.7 and 1.54 mg/mL, respectively, followed by ethyl acetate extract, while the least effective was methanol extract. From those extracts, a total of 35 substances were detected by GC-MS analyses, including 14 newly identified constituents, such as phenolic acids, stearic acid, palmitic acid, fatty acids, pyranones, and benzofurans, which may be responsible for the herbicidal effects of A. pintoi. This study suggests that A. pintoi may be used as a source of bioherbicide to minimize the dependency on harmful synthetic herbicides and enhance rice yield.

Cyperus (Cyperus esculentus L.) is an edible perennial grass-like plant, which propagates exclusively with underground tubers. Its tubers are rich in starch (20–30%), fat (25–35%), sugar (10–20%), protein (10–15%) and dietary fiber (8–9%). In addition, the tubers also contain alkaloids, organic acids, vitamins (C and E), steroids, terpenoids and other active components. The contents of oleic acid and linoleic acid in Cyperus oil are very high, which have important medicinal value and health-promoting properties. Most of the extracts from the tubers, stems and leaves of Cyperus have allelopathic potential and antibacterial, antioxidant and insecticidal activities. In recent years, the planting area of Cyperus has increased significantly all over the world, especially in China and some other countries. This paper presents the current status of Cyperus and the recent trend in research in this area. Published reports on its nutritional contents, active ingredients, medicinal efficacy, antibacterial activity and allelopathic potential were also reviewed. [ABSTRACT FROM AUTHOR]

This study deals with the antialgal properties of allelochemicals present in 3-plants (Mallotus philippensis (Lam.) Muell Arg., Melia azedarach L., Mentha royleana Wall. ex Benth and Raphanus sativus L.). The methanolic leaf extracts of these plants were applied on Chlamydomonas reinhardtii Dangeard to find their antialgal properties. High Performance Liquid Chromatography (HPLC) was used to identifiy and quantify the allelochemicals present in these plants to ascertain their efficacy for growth inhibition of algae. Leaf extracts of plants significantly inhibited the growth of Chlamydomonas reinhardtii Dangeard (p <0.05). The p value for these plant species were: Mentha royleana Wall. ex Benth (p <0.05), Melia azedarach L. (p <0.05), Mallotus philippensis (Lam.) Muell Arg (p <0.01) and Raphanus sativus L. (p <0.01); indicating that number of cells of Chlamydomonas reinhardtii Dangeard were significantly inhibited. The most abundant allelochemicals identified by HPLC in M. royleana were caffeic acid (4.67 µg/ml) followed by rutin, trans-ferulic acid and naringin. The trans-ferulic acid was detected only in Mallotus philippensis (Lam.) Muell Arg but rutin was found in most plants. Most of the allelochemicals were found in Mentha royleana, hence, its extract was comparatively more inhibitory to algal growth. The inhibitory effects of methanolic leaf extracts on growth of C. reinhardtii strongly supports the hypothesis that these test plants have ample potential for use as algaecides due to presence of allelochemicals. [ABSTRACT FROM AUTHOR]

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 and 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 (Echinochloa crusgalli L.) and Kabah (Cyperus rotundus L.). Bermudagrass 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. [ABSTRACT FROM AUTHOR]

We determined the role of endophytic bacteria of C. equietifolia, involved in synthesis of allelochemicals. The root endophytic bacteria were isolated and their biological activity was studied to determine their allelopathic potential in fermentation broth. Twenty one species of endophytic bacteria were isolated from the C. equisetifolia roots, of which Bacillus were the dominant genus, Acinetobacter and Staphylococcus were other dominant genera. These 21 endophytic bacteria inhibited the seeds germination of C. equisetifolia, among which Bacillus amyloliquefaciens was most inhibitory. Main allelopathic components of fermentation broth of 3-endophytic bacteria (Bacillus amyloliquefaciens, Bacillus aryabhattai and Paenibacillus glycanilyticus) with strongest allelopathic potential were rich in phenols, esters, organic acids, aldehydes, alcohols, ketones etc. Among them, two allelopathic substances [2,2'-methylenebis[6-(1,1-dimethylethyl)-4-methyl-Phenol and 1,2,3,4-Butanetetrol] were present in both endophytic bacteria fermentation broth and in root and soil extracts. These results confirmed that the secondary metabolites of C. equisetifolia root endophytic bacteria were allelopathic. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the phytochemical compounds of Aloe vera leaves by using LC-MS and evaluate their antifungal and allelopathic activities in vitro. The ethanol extract of Aloe vera leaves was subjected to evaluate their antifungal activity against three plants pathogenic fungi, Fusarium roseum, Fusarium oxysporum lycopersici and Botrytis cinerea by using the agar plate diffusion plate method. The aqueous extract of Aloe vera leaves was subjected to evaluate the allelopathic potential on germination and seedling growth of durum wheat Triticum durum and Amaranthus hybridus which is an advantice species of cereals. We used the bioassay of germination and seedling growth of both species. By LC-MS analysis, 11 bioactive phytochemical compounds were identified in ethanol extract:5-((S-2'-oxo-4'-hydroxypentyl-2(ßglucopyranosyl-oxy-methyl)chromone, isoaloerisin D, aloenin, aloeninB, aloenin-2ˋ-p-coumaroyl ester, aloe-emodindiglucoside, 10-hydroxyaloin B, 10-hydroxyaloin A, aloin B, aloin A, aloveroside B. The antifungal activity showed that the ethanol extract has an inhibitory activity against all the mycelial strains. The allelopathic effect of different concentrations slowed the kinetics of germination of Triticum durum and Amaranthus hybridus and significantly decreased the rate of final germination of Amaranthus hybridus (100% at C10% and C25%), and a weak effect of inhibition of the germination was noticed for Triticum durum (40% at C25%). The aqueous extract has an inhibitory effect on the length of the roots (98% at C25%) and the height of the stems (100% at C25%) of Triticum durum. All concentrations of the aqueous extract have an inhibitory effect on the root length of Amaranthus hybridus. These results showed that Aloe vera would be suggested as a new potential source of natural herbicides and fungicides. [ABSTRACT FROM AUTHOR]

Weeds are a constant and ubiquitous companion of agricultural production, causing enormous damage to it, which often exceeds the total losses caused by diseases and pests. Alternative weed control methods have proven to be a sustainable, economical and environmentally friendly approach with minimal environmental impact. A promising method from this group is the use of crops with allelopathic potential to regulate weed density in agrophytocenoses. The present study, performed in a laboratory, demonstrates that cold aqueous extracts from aboveground biomass of genotypes of the genus Sorghum (Sorghum sudanense (Piper.) Stapf. and Sorghum vulgare var. Technicum [Körn.]) have an inhibitory effect on seed germination and initial development of the test plant Lactuca sativa L. due to their allelopathic effect. Based on the assessment of the allelopathic potential of the studied genotypes of the genus Sorghum, they can be conditionally arranged in the following ascending order: Sorghum sudanense (Piper.) Stapf., Mutant form M300 / 43 (GI from 116.84% to 19.92%, average 110.1%) → Sorghum sudanense (Piper.) Stapf., Variety Kazitachi (GI from 125.56% to 4.85%, average 74.11%) → Sorghum vulgare var. technicum [Körn.], variety Szegedi 1023 (GI from 116.84% to 35.86%, average 66.12%) → Sorghum vulgare var. technicum [Körn.], local population Mi16N (GI from 82.14% to 0.72%, average 47.03%). The proven allelopathic potential of Sorghum vulgare var. technicum [Körn.] variety Szegedi and local population Mi16N allows them to be used as donors in future breeding programs. Further studies are needed on their allelopathic effect against typical weeds and invasive weed species in agrophytocenoses of cultivated species of the genus Sorghum. [ABSTRACT FROM AUTHOR]

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

Laboratory analyses using the 1st generation bioassay were conducted in the years 2013-2014 to investigate the allelopathic potential of wateralcoholic and aqueous extracts from dry weight of rhizomes and roots as well as stems and leaves of Solidago gigantea. Analysed acceptors were two weed species, i.e. monocotyledonous Echinochloa crus-galli and dicotyledonous Amaranthus retroflexus. When the acceptors (E. crus-galli and A. retroflexus) reached the 2-leaf stage (BBCH 12) they were sprayed with wateralcoholic and aqueous extracts (at concentrations of 12.5%, 10%, 5% and 2.5%) obtained from the donor, i.e. S. gigantea. Results indicate an inhibitory effect of wateralcoholic extracts from aboveground parts (leaves and stems) of S. gigantea in relation to dry weight of E. crus-galli and A. retroflexus. The volume of dry weight reduction in acceptors was dependent on the concentration of extracts produced from the donor plant S. gigantea. Dry weight of E. crus-galli and A. retroflexus was reduced most effectively by two concentrations: 12.5% and 10%. In turn, aqueous extracts from rhizomes and roots of S. gigantea, irrespective of the applied concentration, caused an increase in dry weight of E. crus-galli and A. retroflexus. Only aqueous extracts produced from leaves and stems of S. gigantea, irrespective of their concentration, reduced dry weight in only E. crus-galli.

Allelochemicals released by plants serve as the primary defence by targeting the establishment of weeds and other plants. In this study, 12 different intercrops were assessed over five seasons for total phenol and terpenoid content. A detailed analysis on allelochemicals produced was also done using gas chromatography-mass spectrometry (GC-MS) to correlate with their weed suppression efficiency. Total phenol content of intercrops ranged from 6.5 to 17.6 mg g-1 tissue dry wt, with the highest value in carom followed by sorghum, sunnhemp and marigold. Total terpenoid content of leaf extracts of the intercrops varied from 14.5 to 35.9 ?g g-1 tissue dry wt, wherein pearl millet had maximum terpenoid content (35.9 ?g g-1 tissue dry wt) followed by sunnhemp and sesame. Analysis using GC-MS indicated the presence of some unique as well as common allelochemicals in the experimental intercrops. To correlate the abundance of these allelochemicals released from intercrops with their weed suppression competence, relative neighbour effect (RNE) value was determined for each intercrop. Positive RNE values for sunnhemp, pearl millet and sesame indicate their efficiency in effectively reducing weed population than the other intercrops. Thus, intercrops with high phenolic, terpenoid and other allelochemicals specific to sunnhemp, pearl millet and sesame can be correlated well with weed suppression as perceptible from their RNE values. [ABSTRACT FROM AUTHOR]

Cyperus (Cyperus esculentus L.) is an edible perennial grass-like plant, which propagates exclusively with underground tubers. Its tubers are rich in starch (20–30%), fat (25–35%), sugar (10–20%), protein (10–15%) and dietary fiber (8–9%). In addition, the tubers also contain alkaloids, organic acids, vitamins (C and E), steroids, terpenoids and other active components. The contents of oleic acid and linoleic acid in Cyperus oil are very high, which have important medicinal value and health-promoting properties. Most of the extracts from the tubers, stems and leaves of Cyperus have allelopathic potential and antibacterial, antioxidant and insecticidal activities. In recent years, the planting area of Cyperus has increased significantly all over the world, especially in China and some other countries. This paper presents the current status of Cyperus and the recent trend in research in this area. Published reports on its nutritional contents, active ingredients, medicinal efficacy, antibacterial activity and allelopathic potential were also reviewed.

An experiment trial run to determine the allelopathic effects of apricot leaves on corn, bean, rye and pigweed. This experiment was done with apricot aqueous leaf extract (75% w/v) and leaf powder (3% w/w) treatments and control (without any treats with leaf extract and powder and irrigated with distilled water) during seedling stage. This experiment was carried out as a factorial experiment in complete randomized design with 3 replicates. According to the results, the lowest and the highest loss percentage of shoot and root dry weight, and stem and root length was observed in corn and pigweed under the treats of apricot leaf extract and powder. Electrolyte leakage increased significantly in bean under leaf extract and powder treats and in rye treated with extract compared to control. Both treats of apricot leaf decreased the content of chlorophyll a and b in bean and pigweed, although these pigments increased in corn and rye under mentioned treatments. Increased soluble sugars of bean and corn under leaf aqueous extract and powder and of rye and pigweed under leaf aqueous extract were significantly more than control. However, treatment with aqueous extract increased proline content in all studied plants, but the content of this amino acid increased only in the bean treated with apricot extract powder. A little changes of superoxide dismutase activity were not significant in corn, bean, rye and pigweed treated with aqueous extract and powder compared to the control.

Acacia pennata (L.) Willd (Mimosaceae), a woody climbing plant, is used as a traditional medicinal plant in the South and Southeast Asia regions and has been documented to have various pharmacological effects. However, the allelopathy of this plant still remains unclear. Thus, the allelopathic potential of A. pennata leaf extracts was examined against the seedling growth of dicot plants [alfalfa ( Medicago sativa L.), cress (Lepidium sativum L.), and lettuce (Lactuca sativa L.)] and monocot plants [barnyard grass (Echinochloa crus-galli (L.) Beauv.), Italian ryegrass (Lolium multiflorum Lam.), and timothy ( Phleum pratense L.)] at six different concentrations. The results showed that the A. pennata leaf extracts inhibited the seedling growth of all the test plant species at concentrations ≥3 mg dry weight (D.W.) equivalent extract mL-1. The inhibitory activity of the extracts against both shoot and root growth varied with concentration and tested plants. The concentrations required for 50% inhibition of the test plant shoots and roots were 1.5-16.1 and 1.4-8.6 mg D.W. equivalent extract mL-1, respectively. The root growth of all the test plant species was more sensitive to the extracts than their shoot growth, except alfalfa. The results of the present study indicate that the A. pennata leaf extracts may have allelopathic potential and may contain allelopathic substances. Therefore, further studies are required for isolation and identification of the growth inhibitory substances which are responsible for the allelopathic effect of A. pennata. [ABSTRACT FROM AUTHOR]

Lovegrass (Eragrostis plana) is the most important invasive plant in pastures of southern Brazil. The research evaluated the potential of Ruta graveolens (rue) and Schinus terebinthifolius (Brazilian peppertree) essential oils (EOs) to inhibit germination and initial development of lovegrass. The in vitro treatments tested were control (distilled water), alcohol control, 0.001, 0.005, 0.01, 0.05 and 0.1% (v/v) of both EOs. Higher concentrations of these EOs were applied to germinated plants under greenhouse conditions. The EOs of both species were effective in reducing lovegrass germination, with emphasis on rue. Height and shoot dry mass, at greenhouse conditions, were significantly reduced by both EOs, especially when applied at a concentration of 1%. The results point to the potential of rue and Brazilian peppertree EOs for the formulation of natural herbicides. [ABSTRACT FROM AUTHOR]

The present study aimed to analyze the chemical composition of Symphyotrichum squamatum EOs growing in two different habitats to explore the ecological implication on the EOs production and evaluate their antioxidant and allelopathic potentialities. The EOs from the aerial parts collected from coastal Mediterranean belt and inland abandoned habitats in the Nile Delta of Egypt, were extracted and analyzed using gas chromatography-mass spectrometry. Sixty compounds were characterized as overall constituents of EOs from both samples. Sesquiterpenes were the main component and represented by 69.77% and 88.68% from coastal and inland sample, respectively. The coastal sample attained a relatively high content of monoterpenes compared to the inland sample. Major compounds from the EOs of the coastal habitat sample, were humulene epoxide, (-)-spathulenol, (-)-caryophyllene oxide, germacrene D, and α -humulene representing 59.72%. However, β -pinene, germacrene D, α -humulene, α -muurolene, humulene epoxide, (-)-caryophyllene oxide, and β -cadinene were the major compounds of EOs of the inland habitat sample, representing 63.70%. The correlation analysis revealed more correlation between the Egyptian inland S. squamatum and the Japanese ecospecies. However, the Egyptian coastal S. squamatum and Turkish ecospecies were more correlated to each other. The present data suggested that chemotypes of S. squamatum maintain their typical pattern despite ecological or climatic differences. The EOs of S. squamatum showed moderate antioxidant activity, wherein coastal and inland EOs have an IC 50 value of 382.53 and 559.63 μL L−1, respectively. Also, the EOs from both habitats showed moderate allelopathic activity against the noxious weed Bidens pilosa. However, the activity of the coastal sample was more than inland one and could be attributed to the content of the major compounds, especially the oxygenated terpenes. [ABSTRACT FROM AUTHOR]

The present study was conducted to assess allelopathic activity of diploid and mixoploid fenugreek (Trigonella foenum-graecum) aqueous extracts of dried shoots (10, 20, 30 and 40 g/l) against lettuce (Lactuca sativa), alfalfa (Medicago sativa), and peganum (Peganum harmala). Results showed that fenugreek allelopathic potential was significantly enhanced by polyploidization. Mixoploid plant extracts have more significant effects (P inf 0.05) on all target species than that of diploid plants at all tested concentration levels. At the high concentration of 40 g/l, mixoploid plant extract induced 9% more inhibition on lettuce root growth, 21% more on peganum, and 36% more on alfalfa than that from diploid plant. Based on the whole-range inhibition index for growth, the allelopathic potential of mixoploid plants was enhanced by 24.4% on lettuce, 79.7% on peganum, and 37% on alfalfa. There was a significant difference in sensitivity towards fenugreek allelopathy among the target species with lettuce being the most sensitive and alfalfa the least affected. Such differences were consistent for both mixoploid and diploid plants. Fenugreek may be favorably used in sustainable weed management. Moreover, it seems that polyploidy induction is an effective tool to increase fenugreek allelopathic activity

Use of synthetic herbicides is increasing globally. Application of heavy doses of herbicides is directly / indirectly causing negative impact on crop quality, human health and environment. Allelopathic weeds have wide application prospects in increasing crop production, plant protection and biological control. Current study was conducted to evaluate allelopathic activity of aqueous extracts of Carica papaya, Lantana camara, Rhazya stricta and Pinus roxburghii against selected weeds viz. Phalaris minor, Avena fatua, Chenopodium album, Euphorbia helioscopia and Rumex dentatus on filter paper, soil and agar at 100%, 75%, 50% and 0% concentration. Germination percentage (%), radicle length (cm) and plumule length (cm) were parameters to assess allelopathic potential. The STATISTIX 9 software was used to analyse data. Based on results, it was concluded that aqueous extract of R. stricta, P. roxburghii, C. papaya and L. camara possess potential inhibitory effects amongst which L. camara showed most prominant inhibitory effects towrads weeds. The germination and growth inhibition effects were found in order L. camara>P. roxburghii>R. stricta>C. papaya. Detailed field study is recommended to establish allelopathic potential of these species. [ABSTRACT FROM AUTHOR]

This study was aimed at evaluating allelopathic activity of various solvent extracts of Pinus roxburghii (Pine tree) against some important weeds viz. Phalaris minor (bunchgrass), Avena fatua (wild oat), Chenopodium album (pigweed), Euphorbia helioscopia (sun spurge) and Rumex dentatus (toothed dock) of bread wheat (Triticum aestivum) by employing sandwich method (powdered needles) on filter paper, soil and agar. The data attained from statistical analysis revealed that methanolic needle extract possessed the highest germination percentage inhibition for T. aestivum, followed by C. album and A. fatua applied in soil. Similarly, maximum radical length suppression was observed for R. dentatus, followed by C. album. The plumule length retardation was noted best in R. dentatus, followed by A. fatua. The application of methanolic P. roxburghii extract was responsible for reduction in seed germination, radical and plumule length of wheat. Based on results, it can be concluded that methanolic Pinus needles extract possesses potential inhibitory effects that required for further detailed analysis to establish allelopathic potential and onward application to be used as phytoherbicide. [ABSTRACT FROM AUTHOR]

Several cover crops (CCs) exert allelopathic effects that suppress weed growth. The aim of the present study was to evaluate the effects of aqueous extracts containing different concentrations [0, 0.5, 1, 2.5, 5, 7.5 and 10% (w/v)] of Brassicaceae CCs (Sinapis alba, Raphanus sativus, Camellina sativa) and of the CCs Fagopyrum esculentum and Guizotia abyssinica on germination and early growth of Ambrosia artemisiifolia L. The allelopathic effects were species and concentration-dependent. C. sativa, for example, caused the greatest potential to inhibit germination, shoot, radicle length and fresh seedling weight, whereas S. alba and R. sativus inhibited germination and early growth of A. artemisiifolia only at concentrations ≥7.5%. In contrast, no inhibition was observed when aqueous extracts of F. escultneum and G. abyssinica were added at any of tested concentration. Liquid chromatography-tandem mass spectrometry detected 15 phenolic compounds in Brassicaceae CCs with the highest content (µg/g) of vanillin (48.8), chlorogenic acid (1057), vanilic acid (79), caffeic acid (102.5) and syringic acid (27.3) in C. sativa. Our results suggest that C. sativa is the most allelopathic CCs and that the fruits of C. sativa are the plant organs richest in allelochemicals.

Allelopathic activity of Cuscuta epithymum L. (CVCEY), Cuscuta campestris Yuncker (CVCCA), Phelipanche ramosa (L.) Pomel (ORARA), Phelipanche mutelii (Schultz) Reuter (ORARM) and Phelipanche spp. (PHESS) on germination and initial development of test plats of Lactuca sativa L. cultivar 'Great Lakes' was studied under laboratory conditions. It was found that, water exracts of the parasitic weed species in concentrations 0.4, 0.8, 1.6, 3.2, 6.4 and 12.8% w/v have a relatively high inhibitory effect on the seed germination of test plants. The inhibiting rate of parasitic weed species from family Convolvulaceae ranges from 6.24 to 100.0% and for the species of family Orobanchaceae from 42.1 to 100.0%. Parasitic weed species from family Orobanchaceae (Ph. ramosa, Ph. mutelii and Phelipanche spp.) showed a considerably stronger allelopathic effect (GIaverage 17.9), as compared with the applied concentrations of water exracts of species from family Convolvulaceae (C. epithymum and C. campestris) (GIaverage 22.7).

We studied the polyphenol (phenolic compounds and flavonoids) composition and allelopathic effects of Acacia melanoxylon R. Br. aerial foliage aqueous extract (0%, 25%, 50%, 75% and 100%) on the seedling growth and plant biomass of the general biotest species, lettuce (Lactuca sativa). Mean leaf fresh weight, leaf dry weight, root fresh weight and root dry weight were decreased following exposure to Acacia aerial foliage, flowers aqueous extract (AFE) and phyllodes aqueous extract (APE) after 6 days. The reduction in plant dry biomass was more than 50% following treatment with AFE. The decrease in mean root length was approximately 37.7% and 29.20% following treatment with Acacia flowers extract (AFE) at 75% and 100% concentration, respectively. Root dry weight of L. sativa was reduced by both flowers and phyllodes extract. The reduction of protein contents in lettuce leaves following Acacia foliage extract proved that both AFE and APE exhibit polyphenols that causes the toxicity which led to decrease in leaf protein contents. High-Performance Liquid Chromatography (HPLC) was employed to analyze the A. melanoxylon flowers and phyllodes. A total of 13 compounds (accounting for most abundant compounds in flowers and phyllodes) include different flavonoids and phenolic compounds. The phytochemical compounds detected were: Gallic acid, protocatechuic acid, p-hydroxybenzoic acid, p-hydroxybenzaldehyde, vanillic acid, syringic acid, p-coumaric acid, and ferulic acid. The major flavonoid compounds identified include rutin, luteolin, apigenin, and catechin. Allelopathic effects of flower and phyllodes extracts from A. melanoxylon may be due to the presence of above compounds identified by HPLC analysis.