Antioxidant, antimicrobial and phytotoxic activities of Rhaponticum acaule DC essential oil

The in-vitro antioxidant activity of Rhaponticum acaule essential oil (RaEO) was evaluated using ß-carotene/linoleic acid bleaching, chelating activity, and lipid peroxidation inhibition (TBARS) assays. The antimicrobial activity of RaEO was assessed by disc diffusion and microdilution methods against 8 bacteria and 4 yeast. Finally, the allelopathic activity of RaEO on the seed germination and the shoot and root elongation of lettuce (Lactuca sativa L.) seedlings were investigated. According to our results, the RaEO exhibited significant antioxidant activity, similar to those of standards (BHT and ascorbic acid) with IC50 values of 0.042 and 0.045 mg/mL obtained by ß-carotene bleaching and TBARS assays, respectively. On the other hand, despite its interesting ferrous chelating activity, RaEO possesses moderate IC50 value (0.35 mg/mL) as compared with that of EDTA (0.015 mg/mL). RaEO exhibited a strong antimicrobial activity against all the tested microorganisms, with IZ, MIC and MBC values being in the range of 7.67 ± 0.58 to 13.33 ± 0.58 mm, 1.25 to 5.00 and 5.00 to 10.00 mg/mL, respectively. The results reveled also that RaEO inhibited the shoot and root growth of Lactuca sativa L. seedlings. Our data suggested that the RaEO had pharmaceutical benefits and could be used as a potential natural herbicide resource

Allelopathic Effect of Water Extracts from Rhizosphere Soil of Three Medicinal Plants on Polygala tenuifolia Seeds and Their Seedlings / 中国实验方剂学杂志

Objective:To investigate the allelopathic effects of water extracts from rhizosphere soil of three medicinal plants Rehmannia glutinosa，Pinellia ternata and Isatis indigotica on seed germination and seedling growth of Polygala tenuifolia， screen the stubble varieties suitable for crop rotation with P. tenuifolia， and provide some scientific basis for continuous cropping obstacles of P. tenuifolia. Method:The bioassay method was used to study the effects of rhizosphere soil water extracts from three medicinal plants Rehmannia glutinosa，Pinellia ternata and Isatis indigotica at concentrations of 0.3，0.6，0.9 g·mL-1 on the germination of P. tenuifolia seed and seedling growth. Result:The rhizosphere soil water extracts of Rehmannia glutinosa and Pinellia ternata showed basically low-promotion and high-inhibition concentration effects on the final germination rate，germination potential，and germination index of P. tenuifolia seeds，while the water extract of Isatis indigotica showed significant allelopathic inhibition effect. All three rhizosphere soil water extracts showed significant allelopathic inhibition effects on the growth index of P. tenuifolia seedlings. Among them，the rhizosphere soil water extract of Rehmannia glutinosa showed lower inhibitory effect on the plant height and root length of P. tenuifolia seedlings than the other two water extracts. The photosynthetic pigment content，proline（Pro） content，and soluble sugar content of P. tenuifolia chinensis seedlings were the highest under 0.3 g·mL-1 soil water extract of Rehmannia glutinosa， with relatively higher content of soluble protein， and relatively lower content of hydrogen oxide（H2O2）. Under the treatment of 0.9 g·mL-1 soil water extract of Rehmannia glutinosa，P. tenuifolia seedlings had the highest peroxidase（POD） and superoxide dismutase（SOD） activities，low catalase（CAT） activity，and lowest content of malondialdehyde（MDA）. Conclusion:Based on the comprehensive analysis of the above experimental data and allelopathic effects，the water extract of rhizosphere of Rehmannia glutinosa can promote the germination of P. tenuifolia seeds to a certain extent，and lay the foundation for seedling resistance to biochemical stress. Therefore， Rehmannia glutinosa is more suitable for crop rotation with P. tenuifolia.

Investigating the use of pine needle extract as biological herbicide for weed control in bean crop

Aim: The study was undertaken to investigate the inhibitory effect of pine needle extract (Pinus eldarica) on the vegetative growth of weeds found in bean fields. Methodology: Aqueous extracts [25, 50, 75 and 100% of pine needles were applied to common beans (Phaseolus vulgaris) and weeds (prosomillet and redroot pigweed). The effect extract on seedling growth, physiological and biochemical characteristics were subsequently investigated. The experiment was carried out completely a randomized design with three replicates. Phytochemical compounds of pine needle extracts were determined spectrophotometrically. Results: Extracts of pine needles increased the Chl a, Chl b, total Chl and carotenoid contents of bean varieties in comparison to control; while the level of these pigments were considerably low in weeds. The lowest content of proline and phenolic compounds, as well as the highest peroxidation of biomembrane lipids was detected in redroot pigweed treated with 100% needle extract. Although peroxidase and catalase activities dramatically increased in bean varieties proportional to the extract concentration applied. Auxin oxidase and nitrate reductase activities in both weeds significantly (p<0.05) decreased due to treatment. The sensitivity of weeds to allelochemicals was higher as compared to bean varieties. Content of phenolics and proanthocyanidins were also high in pine needle extracts, which was correlated to the inhibitory effect on the weeds studied. Interpretation: The results of this investigation point to a positive effect of the use of Eldar pine needle extracts as a natural herbicide in comparison to the chemical counter parts.

Phytotoxicity and cytotoxicity of Lepidaploa rufogrisea (Asteraceae) extracts in the plant model Lactuca sativa (Asteraceae) / Fitotoxicidad y citotoxicidad de los extractos de Lepidaploa rufogrisea (Asteraceae) en la planta modelo Lactuca sativa (Asteraceae)

AbstractLepidaploa rufogrisea is a promising candidate in the search of natural herbicides, with compounds (sesquiterpene lactones-glaucolide B) which have been reported to present phytotoxic potential against weeds. Thus, this work aimed to accomplish the phytochemical investigation of L. rufogrisea as well as the evaluation of its biological effects on the plant model Lactuca sativa. To this end, different extracts (aqueous, hydroalcoholic and hexane) of L. rufogrisea at different concentrations [0.25, 0.5, 1.0, 2.0 and 4.0 % (m/v)] were evaluated from macroscopic (percentage of germinated seeds, germination speed index and root length) and microscopic analysis (mitotic index and cell cycle alterations) in plantlets (150 per treatment) and meristematic cells (10 000 per treatment) of L. sativa var. Cristina. The extracts decreased the germination speed index and also the root growth of L. sativa plantlets. Cell proliferation was not significantly affected by the extracts. However, some chromosome and nuclear alterations in the mitotic spindle were observed, due to the interference of allelochemicals present in L. rufogrisea. Moreover, the plant model L. sativa demonstrated to be efficient for this kind of studies.

ResumenLepidaploa rufogrisea es una candidata prometedora en la búsqueda de herbicidas naturales, con compuestos (lactano sesquiterpeno- glaucolíde B) los cuales han sido reportados por presentar un potencial fitotóxico contra las malas hierbas. Por lo tanto, este trabajo tuvo como objetivo lograr la investigación fitoquímica de L. rufogrisea, así como también la evaluación de sus efectos biológicos sobre el modelo de planta Lactuca sativa L. Para esto, diferentes extractos (acuosos, hidroalcohólicos y hexanos) de L. rufogrisea fueron evaluados. El porcentaje de semillas germinadas, el índice de velocidad de germinación y la longitud de raíz de plántulas de L. sativa var. Cristina fueron evaluadas, así como también la citotoxicidad de los extractos en las células meristemáticas. Los extractos disminuyeron el índice de velocidad de germinación y también el crecimiento de las raíces de las plántulas de L. sativa. La proliferación celular no se vio significativamente afectada por los extractos. Sin embargo, se observaron alteraciones cromosómicas y nucleares, debido a la interferencia de los aleloquímicos presentes en L. rufogrisea en el huso mitótico. Además, el modelo de planta L. sativa demostró ser eficiente para tales estudios.

N deposition affects allelopathic potential of Amaranthus retroflexus with different distribution regions

ABSTRACT This study aims to determine the allelopathic potential of Amaranthus retroflexus (Ar) with different climatic zones on seed germination and growth of A. tricolor (At) treated with a gradient N addition. Ar leaf extracts only displayed significantly allelopathic potential on the underground growth of Ar but not the aboveground growth of At. The allelopathic potential of Ar leaf extracts on root length of At were enhanced under N addition and there may be a N-concentration-dependent relationship. The effects of the extracts of Ar leaves that collected from Zhenjiang on seed germination and growth of At may be higher than that collected from Jinan especially on root length of At under medium N addition. This reason may be the contained higher concentration of secondary metabolites for the leaves of plants that growths in high latitudes compare with that growth in low latitudes. This phenomenon may also partly be attributed to the fact that Ar originated in America and/or south-eastern Asia which have higher similarity climate conditions as Zhenjiang rather than Jinan. The allelopathic potential of Ar on seed germination and growth of acceptor species may play an important role in its successful invasion especially in the distribution region with low latitudes.

Salvia officinalis L. coverage on plants development / Cobertura de Salvia officinalis L. no desenvolvimento de plantas

ABSTRACT Medicinal plants with essential oils in their composition havetypicallybeen shown to be promising in plant control. Sage (Salvia officinalis L.) is cited for its allelopathic effects. This study evaluated the allelopathic potential of dried sage leaves in vegetation, soil and the development of Lycopersicon esculentum Mill. (tomato), Panicum maximum Jacq. (guinea grass) and Salvia hispanica L. (chia) plants. Three seedlings were transplanted seven days after germination in 1 kg plastic containers with soil, in a greenhouse. The grinded dry mass of sage was placed at rates of 3.75; 7.5 15 t ha-1, and a control (no mass). After 30 days, the chlorophyll index of tomato and guinea grass plants were inhibited with 7.5 and 15 t ha-1 sage cover crops. Tomato shoot length was inhibited in all tested rates, and guinea grass plants showed some reduction in growth when using the highest rate of sage mass (15 t ha-1). The dry mass of tomato and guinea grass plants was reduced when using the15 t ha-1, and 7.5 and 15 t ha-1 of sage cover crops, respectively. It can be concluded that there was some effect of sage coverage on the soil in tomato and guinea grass, but no effect was observed on chia plants.

RESUMO As plantas medicinais que apresentam óleos essenciais em sua composição normalmente têm se mostrado promissoras no controle de plantas. A sálvia (Salvia officinalis L.) é citada por seus efeitos alelopáticos. Assim, esse estudo avaliou o potencial alelopático das folhas secas de sálvia na cobertura vegetal, no solo, sobre o desenvolvimento das plantas de Lycopersicon esculentum Mill. (tomate), Panicum maximum Jacq. (capim mombaça) e Salvia hispanica L. (chia). Três plântulas foram transplantadas, sete dias após germinação, em vasos plásticos de 1 kg, com terra, em casa de vegetação. Sobre elas foi disposta a massa seca triturada de sálvia nas proporções 3,75; 7,5 e 15 t ha-1, além da testemunha (sem massa). Após 30 dias, o teor de clorofila das plantas de tomate e capim mombaça foi inibido com 7,5 e 15 t ha-1 de sálvia em cobertura. O comprimento da parte aérea do tomate foi inibido em todas as proporções testadas e as plantas de capim mombaça apresentaram redução do crescimento quando se utilizou 15 t ha-1 de sálvia como cobertura. A massa seca das plantas de tomate e capim mombaça reduziu com o uso de 15 t ha-1 e, 7,5 e 15 t ha-1 de sálvia como cobertura, respectivamente. Finalmente, pode-se concluir que houve efeito da sálvia em cobertura sobre o solo em tomate e capim mombaça, mas não houve efeito da mesma sobre as plantas de chia.

Residues of Citrus sinensis (L) Osbeck as agents that cause a change in antioxidant defense in plants / Resíduos de Citrus sinensis (L) Osbeck como agentes que causam uma alteração na defesa antioxidante em plantas

This work aimed to verify the allelopathic potential of the extract of Citrus seeds, for the purpose of adding a sustainable value to the fruit seeds toward their use as industrial residues. The extract was obtained with a Soxhlet apparatus by using hexane, chloroform, and methanol as solvents. The hexane extract of the Citrus seeds primarily consisted of linoleic acid (36.6%), followed by α-linoleic acid (25.3%), oleic acid (17.8%), palmitic acid (9.7%), and estearic acid (3.3%). The analysis results indicate that the oil is similar to those used in the cosmetics and food industries and has an economic value from its industrial application. In addition, the use of the oil causes changes in the oxidant balance, germination, and growth of plants...

Este trabalho teve como objetivo verificar o potencial alelopático do extrato de sementes de Citrus, com o objetivo de agregar valor sustentável para a semente de frutas para a sua utilização como resíduo industrial. O extrato foi obtido com aparelho de Soxhlet, utilizando hexano, clorofórmio e metanol como solventes. O extrato hexânico das sementes de Citrus constituiu principalmente por ácido linoleico (36,6%), seguido por ácido α-linoleico (25,3%), ácido oleico (17,8%), ácido palmítico (9,7%) e ácido esteárico (3,3%). As análises indicam que o óleo é semelhante aos utilizados na indústria de cosméticos e de alimentos, tem valor econômico para a utilização na indústria e seu uso provoca alterações no equilíbrio oxidativo, germinação e crescimento...

Efeito de solo previamente cultivado com plantas aromáticas na germinação e no desenvolvimento inicial de alface / Outcomes of soil previously treated with aromatic plants in the germination and early growth of lettuce

RESUMOO objetivo desse trabalho foi verificar o efeito do solo pré-cultivado com plantas aromáticas na germinação e no desenvolvimento inicial de plântulas de alface cv. Simpson. A pesquisa foi realizada na Embrapa Hortaliças, Brasília, em bandejas mantidas em casa de vegetação. O experimento foi conduzido em delineamento experimental inteiramente casualizado, com três repetições e onze tratamentos: solo pré-cultivado com hortelã-comum (Mentha x villosa), hortelã-brava (Mentha arvensis), hortelã-pimenta (Mentha piperita), Mentha spp., capim-citronela (Cymbopogon winterianus), capim-limão (Cymbopogon citratus), manjericão de folha larga (Ocimum basilicum), manjericão de folha roxa (Ocimum gratissimun), tomilho (Thymus vulgaris), sálvia (Salvia officinalis) e solo da mesma área sem cultivo prévio de planta aromática (controle). Aos 30 dias após o semeio, foram avaliadas: índice de velocidade de emergência (IVE), taxa de sobrevivência (TS), número de folhas (NF), comprimento da raiz principal (CRP) e da parte aérea (CPA), massa fresca da raiz (MFR) e da parte aérea (MFPA) e massa seca da raiz (MSR) e da parte aérea (MSPA). Os dados foram submetidos à análise de variância e teste de Tukey a 5% de probabilidade. Houve diferença significativa em relação ao IVE, sendo que o tratamento com C. citratus afetou negativamente a emergência das plântulas. O tratamento com M. arvensis apresentou uma TS de apenas 16% das plantas aos 30 dias após a semeadura. O NF foi menor no tratamento com M. arvensis, diferentemente de todos os demais, exceto S. officinalis. A MRF e MFF foram estimuladas pelo tratamento com T. vulgaris sendo superior a todos os outros tratamentos. Os resultados obtidos permitem concluir que houve efeito negativo de M. arvensis e positivo de T. vulgaris no desenvolvimento inicial de plântulas de alface.

ABSTRACTThis study aimed to verify the outcomesof the soil previously treated with aromatic plants in the germination and early seedling growth of lettuce var. Simpson under greenhouse conditions. The trial was developed at Embrapa Vegetables, in Brasília, Brazil in a completely randomized design with three replications and composed by eleven treatments as follow: soil cultivated with apple-mint (Mentha x villosa), wild mint (Mentha arvensis), peppermint (Mentha piperita), Mentha spp., citronella (Cymbopogon winterianus), lemon grass (Cymbopogoncitratus), basil (Ocimum basilicum), african basil (Ocimum gratissimun), thyme (Thymus vulgaris), sage (Salvia officinalis) and soil from the same area without prior cultivation of aromatic plant (control). The emergence velocity index (IVE), the survival rate (SR), the number of leaves (NL), the length of the main root (CRP) and the shoot (CPA), the fresh mass of the root (MFR) and the shoot (MFPA) and the dry mass of the root (MSR) and the shoot (MSPA), were evaluated 30 days after the sowing. The data were submitted to analysis of variance and Tukey's test at 5% probability. There was a significant difference regarding the IVE, in which the treatment with C.citratus negatively affected seedlingappearance. The treatment with M. arvensis showeda TS of only 16%at 30 days after the sowing. The NF was lower in the treatment with M. arvensis, differently from all the others, excepting the cultivation withS. officinalis. The MFR and the MFPA were stimulated by the treatment with T. vulgaris, which was higher than all the other cultivations. The obtained results showed that M. arvensis had a negative influence,while T.vulgaris presented a positive outcome in the early development of lettuce seedlings.

Allelopathic Effect of Cell-Free Medium of Microcystis aeruginosa Kützing on the Chromosomal Changes in Allium cepa Root Tips and Plumule Formation of Zea mays Seedling.

This work confirm the allelopathic toxic effect of both cell-free medium in log and death phase of growth of Microcystis aeruginosa on chromosomal changes of Allium cepa root tips and the plumule formation of Zea mays seedlings. The results showed high significant inhibition of mitotic index in Allium cepa root tips in addition, chromosomal abnormalities were also detected. There were morphological change occurred in the plumule formation of Zea mays seedlings. The results revealed that, seed soaked in log phase cell-free medium had less inhibitory effect on plumule formation than that the seed soaked in death phase cell-free medium of M. aeruginosa. This was confirmed by the allelopathic effect of toxins released during death phase of growth was more than log phase.

Potencial alelopático e antioxidante de extratos vegetais / Allelopathic and antioxidant potential of plants extracts

Objetivou-se com este trabalho avaliar a atividade alelopática, antioxidante e o conteúdo de fenóis e flavonóides totais no extrato metanólico de quatro plantas medicinais: Hibiscus sabdariffa, Ocimum gratissimum, Palicourea crocea e Trichilia silvatica. Para isso, folhas, flores e caules de Trichilia silvatica, folhas de Palicourea crocea, cálice e folhas de Hibiscus sabdariffa e folhas de Ocimum gratissimum foram utilizados. A avaliação da atividade alelopática foi realizada pelo ensaio de germinação e crescimento inicial de sementes de alface (Lactuca sativa), com três repetições de 50 sementes em delineamento inteiramente casualizado. A atividade antioxidante foi determinada pelo método fotocolorimétrico in vitro do radical livre estável 2,2-difenil-1-picril-hidrazila (DPPH). O crescimento das plântulas de alface foi mais sensível à ação dos aleloquímicos presentes nos extratos metanólicos do que a germinação das sementes, e evidenciaram o efeito inibitório dos extratos metanólicos do cálice e folhas de H. sabdariffa e das folhas de O. gratissimum e P. crocea. Os extratos metanólicos obtidos das folhas, flores e casca de T. silvatica apresentaram maior capacidade de sequestrar radicais livres com valores de IC50 de 62,36; 19,4 18,38 µg mL-1, no ensaio com DPPH e maior teor de compostos fenólicos 520,80; 545,27 e 546,56 mg de ácido gálico g de amostra-1, respectivamente, avaliado pelo ensaio de Folin-Ciocalteau.

The aim of this work was to evaluate allelopathic and antioxidant activity and total flavonoids and phenols content in methanolic extract of four medicinal plants: Hibiscus sabdariffa, Ocimum gratissimum, Palicourea crocea and Trichilia silvatica. Leaves (TSFo), flowers (TSFl) and stems (TSCa) of T. silvatica; leaves (PCFo) of P. crocea; chalice (HSCa) and leaves (HSFo) of H. sabdariffa and leaves of O. gratissimum (OGFo) were used in experiment. The evaluation of allelopathic activity was carried out by test of seed germination and initial growth of lettuce seedlings (Lactuca sativa), with three replications of 50 seeds in completely randomized design. The antioxidant activity was determined by method photo colorimetric in vitro of stable free radical 2.2-diphenyl-1-picrylhydrazyl (DPPH). The growth of lettuce seedlings was more sensitive to the action of allelochemicals in methanolic extracts than seeds germination, and showed the inhibitory effect of methanolic extracts from leaves and chalice of H. sabdariffa and leaves of O. gratissimum and P. crocea. Methanolic extracts obtained from the leaves (TSFo), flowers (TSFl) and bark (TSCa) of T. silvatica showed higher ability to scavenging free radical with IC50 values of 62.36; 19.4 18.38 µg mL-1, in assay with DPPH and highest content of phenolics, 520.80; 545.27 546.56 mg gallic acid per g of sample, respectively, evaluated by the Folin-Ciocalteau assay.

Alelopatia de extratos de adubos verdes sobre a germinação e crescimento inicial de alface / Allelopathy of green manures extracts on germination and initial growth of the lettuce

Extratos aquosos obtidos de palhas de três gramíneas e três leguminosas nas concentrações de 2,5%, 5% e 10% foram preparados com o objetivo de determinar o potencial alelopático dessas espécies utilizadas como adubos verdes sobre alface (Lactuca sativa L.), e estimar a melhor concentração para uso desses extratos em bioensaios de laboratório. Para análise da germinação foram consideradas as variáveis porcentagem de germinação e índice de velocidade de germinação. Para análise do crescimento inicial consideraram-se as variáveis porcentagem de plantas normais, comprimento de raiz e parte aérea, massa fresca de raiz e parte aérea e massa seca de raiz e parte aérea. Os adubos verdes utilizados para preparação dos extratos foram as leguminosas crotalária (Crotalaria anagyroides H.B.K.), feijão-de-porco (Canavalia ensiformis (L.) DC) e guandu-anão Cajanus cajan (L). Millsp e as poaceas aveiapreta (Avena strigosa Schieb), sorgo (Sorghum bicolor (L.) Moench) e milheto (Pennisetum glaucum (L.) R. Brown), em cultivo exclusivo e consorciadas, perfazendo dezesseis tratamentos (crotalária, feijão-de-porco, guandu-anão, aveiapreta, sorgo, milheto, crotalária + aveia-preta, crotalária + sorgo, crotalária + milheto, feijão-de-porco + aveia-preta, feijão-de-porco + sorgo, feijão-de-porco + milheto, guandu-anão + aveia-preta, guandu-anão + sorgo, guandu-anão + milheto e testemunha). Adotou-se um arranjo fatorial 16 x 3 (quinze extratos de adubos verdes e testemunha x três concentrações), com três repetições. Os extratos que proporcionam maior efeito nas variáveis estudadas são os de feijão-de-porco e feijão-de-porco + aveia preta e a concentração que melhor estima o efeito dos extratos de adubo verdes é 5%.

Aqueous extracts obtained from three Poaceae species and three legume species straws at concentrations of 2,5%, 5% and 10% were prepared in order to determine the allelopathic potential of these species used as green manures on lettuce (Lactuca sativa L.), and to estimate these extracts optimal concentration for use in laboratory bioassays. For germination analysis, it was considered the variables percent germination and speed of germination index. For initial growth analysis, it was considered the variables percentage of normal plants, radicle and shoot lengths, and fresh and dry weight of the radicle and shoot. Green manures used for the preparation of extracts were the legume species sunn hemp(Crotalaria anagyroides H.B.K.), jack bean (Canavalia ensiformis (L.) DC) and pigeon pea (Cajanus cajan (L). Millsp and the Poaceae species black oat (Avena strigosa Schieb), shattercane (Sorghum bicolor (L.) Moench) and millet (Pennisetum glaucum (L.) R. Brown), with and without intercropping, completing a total of sixteen treatments (sun hemp, jack bean, pigeon pea, black oat, shattercane, millet, sun hemp + black oat, sun hemp + shattercane, sun hemp + millet, jack bean + black oat, jack bean + shattercane, jack bean + millet, pigeon pea + black oat, pigeon pea + shattercane, pigeon pea + millet and control). It was adopted a 16 x 3 factorial design (Fifteen green manures and the control X three concentrations) with three repetitions. The extracts that provide the greatest effect on the studied variables were from jack bean and jack bean + black oat and the concentration that best estimates the effect of green manures extracts of is 5%.

Allelopathic effect of Tridax procumben on four kinds of crops / 中草药

Objective: To study the allelopathic effect of water extract from Tridax procumbens (WETP) on the seed germination and seedling growth of four kinds of crops. Methods: By water extraction, the stems, leaves, and seeds of T. procumbens were extracted, respectively. The seeds and seedlings of the four kinds of crops were treated with WETP, using distilled water as a control, and the differences between the seeds at four kinds of concentration were analyzed. Results: The synthetic action of WETP on Vigna radiata is promoting. With the increasing concentration, the promoting is diminished. But the effects of WETP on Raphanus sativus, Brassica campestris, and Lactuca sativa were promoting at low concentration and inhibition at high concentration. The inhibitory sequences of water extracts of different parts were seeds > leaves > stems, and for the seeds, L. sativa > R. sativus > B. campestris > V. radiata. The inhibition on L. sativa was the most significant. Conclusion: T. procumbens has the allelopathic effect on native plants. Therefore, T. procumbens could be used as herbicide and cover plant for competition to inhibit other weeds. It has a development and application value.

Efeito alelopático de folhas de bamburral [Hyptis suaveolens (L. ) Poit] sobre a germinação de sementes de sorgo (Sorghum vulgare Pers. ), rabanete (Raphanus sativus L. ) e alface (Lactuca sativa L. ) / Allelopathic effects of leaves of "bamburral" [Hyptis suaveolens (L. ) Poit] on the germination of seeds of sorghum (Sorghum vulgare Pers. ), radish (Raphanus sativus L. ) and lettuce (Lactuca sativa L. )

O objetivo do presente trabalho foi à verificação do efeito alelopático de Hyptis. suaveolens na germinação de sorgo, alface e rabanete, bem como, a comprovação da existência de compostos com potencial alelopático. Sementes de sorgo, alface e rabanete foram semeadas em substrato constituído de areia, terra e adubo orgânico contendo folhas de H. suaveolens. As análises da germinação foram feitas considerando a protrusão da radícula para o término do evento germinativo. Foi calculado o IVG (índice de velocidade de germinação) e %G (porcentagem de germinação). Os resultados mostraram que sorgo e a alface foram mais susceptíveis ao potencial alelopático de H. suaveolens, sendo que para o rabanete foi observado um efeito benéfico. Entre os tratamentos, o substrato esterilizado e não esterilizado mostraram diferenças entre si. A análise cromatográfica do óleo essencial presente nas folhas de H. suaveolens revelou a presença de compostos com potencial alelopático. Portanto, H. suaveolens, pode apresentar efeito alelopático positivo no IVG de sementes de rabanete e a presença de microorganismos pode ser necessária para que esse efeito alelopático aconteça.

The aim of this study was to verify the allelopathic effect of H. suaveolens on the germination of sorghum, lettuce and radish, as well as to prove the existence of compounds with allelopathic potential. Seeds of sorghum, lettuce and radish were sown in substrate consisting of sand, soil and organic fertilizer containing leaves of H. suaveolens. The germination tests were performed considering the protrusion of the radicle for the conclusion of the germinative event. GSI (germination speed index) and G% (percentage of germination) were calculated. The results showed that sorghum and lettuce were more susceptible to the allelopathic potential of H. suaveolens, while for radishes a beneficial effect was observed. Between treatments, the sterilized and unsterilized substrate showed differences. The chromatographic analysis of essential oil present in the leaves of H. suaveolens revealed the presence of compounds with allelopathic potential. Therefore, H. suaveolens may have positive allelopathic effect on the GSI of radish seeds, and the presence of microorganisms may be necessary for such an allelopathic effect to occur.

Avaliação do potencial alelopático, atividade antimicrobiana e antioxidante dos extratos orgânicos das folhas de Pyrostegia venusta (Ker Gawl. ) Miers (Bignoniaceae) / Evaluation of allelopathic potential, antimicrobial and antioxidant activities of Pyrostegia venusta (Ker Gawl. ) Miers (Bignoniaceae) leaf organic extracts

Este trabalho apresenta os resultados de atividade alelopática, antimicrobiana e antioxidante dos extratos orgânicos (hexano, acetato de etila e metanol) das folhas de Pyrostegia venusta (Ker Gawl.) Miers (Bignoniaceae). Para alelopatia, foi estudado o desenvolvimento de Cucumis sativus (pepino), sendo avaliados o comprimento da raiz principal, o número de raízes secundárias e o comprimento do hipocótilo. Os dois primeiros parâmetros foram afetados por todos os três extratos testados enquanto o comprimento do hipocótilo só não foi afetado pelo extrato acetato de etila. Quanto à atividade antimicrobiana, avaliada pelo ensaio de CIM, o extrato hexânico apresentou inibição moderada frente ao Staphylococcus aureus (0,9 mg mL-1) e forte ao Enterococcus hirae (0,5 mg mL-1). O extrato acetato de etila apresentou forte atividade frente Candida albicans (0,3 mg mL-1) enquanto o extrato metanólico não mostrou-se ativo para os microrganismos testados. Por outro lado, o extrato metanólico apresentou a maior capacidade de seqüestrar radicais livres (Concentração Efetiva 50 por cento-CE50 =102,0 ± 56,9 mg mL-1, com TCE50 = 30 min) no ensaio com DPPH (2,2-difenil-1-picril-hidrazila) e o maior teor de compostos fenólicos (116,2 ± 83,0 mg ácido gálico g amostra-1), avaliado pelo ensaio de Folin-Ciocalteau.

This paper presents the results of allelopathic, antimicrobial and antioxidant activities of organic extracts (hexane, ethyl acetate and methanol) from the leaves of Pyrostegia venusta (Ker Gawl.) Miers (Bignoniaceae). Allelopathic activity was assessed based on Cucumis sativus (cucumber) development for the parameters main root length, number of secondary roots and hypocotyl length. All tested extracts affected the first two parameters, while the hypocotyl length was not affected only by the ethyl acetate extract. For antimicrobial activity, assessed by MIC assay, hexane extract showed moderate inhibition for Staphylococcus aureus (0.9 mg mL-1) and strong inhibition for Enterococcus hirae (0.5 mg mL-1). Ethyl acetate extract showed strong activity against Candida albicans (0.3 mg mL-1), whereas methanolic extract was not active against the tested microorganisms. On the other hand, methanol extract showed the most promising radical scavenging capacity (Effective Concentration 50 percent - EC50 = 102.0 ± 56.9 mg mL-1, with TEC50 = 30 min) in DPPH assay (2,2-diphenyl-1-picryl-hidrazil) and the highest level of phenolic compounds (116.2 ± 83.0 mg acid garlic g sample-1), as indicated by Folin-Ciocalteau assay.

Autotoxicity of water extracts from rhizosphere soil of cultivated Angelica sinensis and identification of their allelopathic compounds / 中草药

Objective: To explore the relationship between continuous cropping obstacle and autotoxicity of Angelica sinensis, autotoxic effect and organic compounds of rhizosphere soil water extract were determined. Methods: Distilled water (CK), water extract of rhizosphere soil (100, 125, 250, and 500 mg/ mL) were applied to testing their effect on early development of A. sinensis. Seed germination rate, germination index, elongation of radicle and embryo were recorded, and GC-MS was conducted for the compound identification in the extract. Results: The water extract at concentraion as low as 125 mg/mL significantly inhibited the germination and seedling growth of A. sinensis, and this inhibitory effect generally increased with the increase of the concentration of water extracts. Seventeen compounds in rhizosphere soil water extract were identified, including organic acids, ketones, aldehydes, esters, and hydrocarbons, most of them are allelophathic substance. Conclusion: Water extracts from A. sinensis rhizosphere soil have inhibitory effects on A. sinensis germination and seedling growth, and this inhibitory effect generally increased with the increases of the water extract concentration at a certain ranges. In conclusion, there is autotoxicity in continuous cropping of A. sinensis, which is one of the causes of problems associated with the continuous cropping obstacle of a single plant species.

Atividades alelopáticas de nim sobre o crescimento de sorgo, alface e picão-preto / Allelopathic activities of nim on the growth of sorghum, lettuce and Bidens pilosa

A busca de alternativas para os herbicidas sintéticos, como os produtos naturais provenientes de plantas, pode acrescentar mais um elemento no manejo das plantas daninhas das culturas. Neste trabalho objetivou-se verificar o potencial alelopático do nim (Azadirachta indica A. Juss.) sobre o crescimento de plântulas de sorgo, alface e picão-preto. Extratos metanólico, aquoso e hexanólico, nas concentrações de 10, 5 e 2,5 por cento (p/v) de folhas de nim, foram usados para irrigar sementes das plantas teste, em caixas gerbox, permanecendo em incubadora, tipo BOD. O percentual de germinação de sementes de alface e picão-preto irrigadas com extrato aquoso e metanólico, respectivamente, foram os mais prejudiciais ao desenvolvimento das plântulas; para o sorgo independente do extrator utilizado, o aumento da concentração causou redução do percentual de germinação. O extrato aquoso causou maior efeito detrimental sobre o índice de velocidade de germinação para as três espécies estudadas. Para o sorgo, independente da concentração avaliada, o extrato aquoso foi o mais prejudicial, diferenciando dos demais extratores, com médias de 8,00; 12,986 e 14,68, para os extratores água destilada, hexanol e metanol, respectivamente. Quando se analisou o acúmulo de biomassa para plantas de picão-preto e sorgo, em todos os extratos utilizados, pôde-se verificar que o acúmulo de biomassa foi inversamente proporcional à concentração de nim aplicada.

The search for alternatives for the synthetic herbicides, as the natural products from plants, may increase one more element to the handling of the harmful plants of the cultures. The aim of this work was to verify the allelopathic effects of neem (Azadirachta indica A. Juss.) upon sorghum, lettuce, and Bidens pilosa L. (beggustick) seeds germination and seedlings growth. Aqueous, methanolic, and hexanolic extracts, in the concentrations of 10, 5 and 2,5 percent (w/v) of nim leaves, were used to irrigate seeds of the plant test, in gerbox boxes, staying in incubator, type BOD. Germination percentages of lettuce seeds and beggustick irrigated with aqueous and methanolic extracts, respectively, were the most harmful to the development of the plants; for sorghum, independently of the used extractor, the increase of the concentration caused reduction of the germination percentages. The aqueous extract caused larger detrimental effect on the index of germination speed for the three studied species. For the sorghum, independently of the appraised concentration, the aqueous extract was the most harmful, differing from the other extractors, with averages of 8.00; 12.986 and 14.68, for the extractors distilled water, hexanol and methanol, respectively. When the biomass accumulation was analyzed for beggustick plants and sorghum, in all used extracts, it could be verified that the biomass accumulation was inversely proportional to the concentration of applied neem.