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Allelopathy is a phenomenon that involves the production of secondary metabolites that influence the growth of plants and microorganisms; however, this alellopathic effect has been scarcely studied on the rhizobia-legume symbiosis. The aims of this research were 1) to assess the allelopathic potential of aqueous extracts of Ipomoea purpurea L. Roth on seed germination and root length of common bean seedlings (Phaseolus vulgaris L.), 2) to determine its effects on the in vitro growth of Rhizobium tropici CIAT899, and 3) to evaluate the allelopathic potential of I. purpurea on the growth, nodulation and physiology of common bean plants inoculated with R. tropici. After 48h, 15% of the aqueous root extract of I. purpurea stimulated seed germination, whereas 4% of the aqueous shoot extracts stimulated such germination. Both the root or shoot extracts stimulated seed germination and e root length. In vitro growth of R. tropici was inhibited as a result of the application of both aqueous extracts. The presence of I. purpurea negatively affected both the growth and physiological responses of common bean plants, and this effect was attenuated after the inoculation of R. tropici; nevertheless, this allelopathic plant affected root nodulation. Our results suggest that the symbiosis of rhizobia and roots of common bean plants is an important element for attenuating the negative effects caused by the allelopathic plant., (Copyright © 2018 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.)

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Copyright of Revista Mexicana de Ciencias Agrícolas is the property of Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias 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.)

Understanding forest dynamics is fundamental to their ecological restoration. This is particularly important in forests rich in species of commercial value, such as those of the Juglans genus, which known allelopathic effect could have an impact on the diversity of locations where it exists. The objective of this study was to evaluate the floristic composition and tree diversity of a forest dominated by Juglans neotropica Diels, establishing a permanent plot of 100 x 100 m in the Chanchamayo valley. In the plot, all trees were evaluated with DBH = 10 cm. The permanent plot presented 300 individuals, which corresponded to 47 species in 20 families. The Fisher's Alpha diversity index value was 15.62, and the Shannon-Wiener index value 1.65. These values are notoriously low in comparison with similar sites located in tropical premontane forests referred to in the present work. Due to the allelopathic nature of J. neotropica Diels, it is possible that this condition is a determining factor for the high abundance of this species in the plot and the low tree diversity identified. Since J. neotropica Diels is categorized as endangered by IUCN, the area becomes an important location for its conservation and that of its gene pool. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia 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.)

Tithonia diversifolia (Hemsl.) A. Gray has been recommended as a fertilizer species and its liquid extract as a biofertilizer in organic agroforestry systems. However, studies indicate that plant extracts have inhibitory effects on the germination and growth of several plant species, acting as allelopathic. In this sense, the work aims to evaluate, on a laboratory scale, the biological effect of concentrations of aqueous extract of T. diversifolia on the germination and initial development of seeds, using lettuce as an indicator species. Aqueous extracts were produced at concentrations of 5%, 10%, 15%, and 20%, using distilled water as a control. Lettuce seeds were arranged in Gerbox boxes, on filter paper, in the amount of 25 seeds per box, under a constant temperature of 20°C and natural light, for seven days. The percentage of final germination, mean germination time (MGT), germination speed index (GSI), and phytosanitary status of the seed on the seventh day were evaluated. The aqueous extracts of T. diversifolia in concentrations between 5% and 20% do not affect the final germination of the seeds, however, they reduce the germination speed; affect seedling size, and induce a higher percentage of abnormalities in germinated seeds. The results suggest that extracts of T. diversifolia have allelopathic potential for the germination of species. [ABSTRACT FROM AUTHOR]

The allelopathic effect of concentrations of extracts of the aerial section of Chloris gayana under the germination of soybean seeds and hairy beggartick is evaluated. Assay was conducted in a totally randomized design where seeds were placed on germitest paper with an aqueous extract of leaves of C. gayana in concentrations 0, 25, 50, 75 and 100% and maintained in a germination chamber at 25°C for a 12-h light photoperiod. Variables analyzed comprised first germination count, germination percentage, germination speed index, length and dry mass of root, aerial and total section. Data underwent analysis of variance by test F (p<0.05) and regression analysis for different concentrations of the extract. Results showed that aqueous extract of C. gayana may significantly affect the germination and initial growth of seedlings, with a reduction of up to 26% on soybean germination with 50% concentration, plus the lowest development of seedlings of both species as from 25% of extract. Results show that aqueous extracts of Chloris gayana leaves have an allelopathic effect on seed germination and growth of soybean seedlings at concentrations 50 and 100%, respectively. In the case of hairy beggartick, there was no significant effect of the extracts in seed germination, except for total length and total dry mass of the seedlings, at concentrations 50 and 75%, respectively. [ABSTRACT FROM AUTHOR]

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Agroforest systems make possible ecologically viable exploitation of forest and crop species. Pityrocarpa moniliformis is a forest species with high apiculture value and, consequently, an extra profit source for farmers, whilst corn is one of the main species as a food basis due to its carbohydrates and proteins. Research work is required on possible interactivities established between forest and crop species, such as allelopathy. A possible allelopathic influence of the dry leaves of Pityrocarpa moniliformis in decomposition may be identified on the establishment and development of corn seedlings, var. Ibra. The presence or absence of alkaloids, triterpenoids, steroids, saponins, coumarins, phenolic compounds, tannins, flavonoids, anthraquinones, anthocyanidins, chalcones, leucoanthocyanidins, catechins and flavonones, was identified through qualitative characteristics for the aqueous extract of the dry leaves of Pityrocarpa moniliformis by totally randomized and factorial design The establishment of seedlings through percentage, speed index and mean emergence time and early development, height of aerial part, length of root system, dry mass of aerial and root section and total were undertaken. Alkaloids, triterpenoids, saponins, phenolic compounds, tannins, flavonoids, anthraquinones, catechins and flavonones, potentially allelopathic compounds, were extant in the foliar extract. Corn as an integral part of an agri-forest system with P. moniliformis is not recommended. [ABSTRACT FROM AUTHOR]

Agriculture is affected by the appearance of weeds that reduce crop production. These are controlled with agricultural chemicals that unbalance the environment and human health. For this reason, the need arises to extract the bioactive compounds from these, to produce and apply powerful bioherbicides, which inhibit the spread of weeds that disturb the crops. Recently, the use of biological extracts of plants has been reported, where it is shown that they have phytotoxic bioactive properties that alter cell structure. The objective of this bibliographic review was to report the advances in the development of new biological herbicides, from phytotoxic plant extracts applied in vitro. This review describes the compounds with phytotoxic capacity in plants and their phytotoxic biological activity, such as polyphenols, tannins, alkaloids, quinones, saponins antagonists, and glycosides, to mention some, through the use of the most common experimental methods that include the extraction, determination, and quantification of the metabolites. In addition, the response variables that were considered to evaluate the effect of these biological active substances are mentioned, which include the percentage of inhibition of germination, growth, and root length in plants. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the potential allelopathic effects of isolated or intercropped aqueous forage extracts on the physiological performance of soybean [Glycine max (L.) Merr.] and corn (Zea mays L.) seeds, as well as their phytotoxicity to the weed species Bidens pilosa L. Aqueous extracts were prepared at a concentration of 5%, and the tests with soy and corn were conducted by wetting the germination papers with different treatments and performing procedures within the standards of the Brazilian Rules of Seed Analysis. Tests with the cover plant extracts on the seeds of B. pilosa used BOD-type repetitions. Fifty weed seeds were placed in a gerbox with filter paper moistened with the different treatments with five repetitions. Distilled water was used as the control in all tests. Extracts of Avena strigosa Schreb and Raphanus sativus L. (radish), cultivated individually and in combination, increased the seed germination percentage (%G) and the length of soybean seedlings. Similarly, extracts of Pennisetum glaucum (L.) R.Br and Crotalaria spectabilis Roth, in individual and combined cultivation, provided gains in corn %G. Furthermore, all tested extracts suppressed germination and decreased the speed of the germination index of the hairy beggarticks when compared to the control, with the radish extract showing the greater reduction effect on the %G of the weed plant B. pilosa. [ABSTRACT FROM AUTHOR]

Introduction: Allelopathy is a harmful effect indirectly or directly produced by one plant to another through the production of chemical substances that enter the environment. Allelopathy has a pertinent significance for systems of ecological, sustainable, and integrated management. These natural reactions have multiple effects, ranging from processes of inhibition and stimulation of growth in neighbor plants to inhibition of seed germination. Metabolomics is a discipline integral that studies all the metabolites in a particular tissue, organ, or organism in a specific developmental stage or under particular environmental conditions, and it allows for the assessment of the contribution of genetic and environmental factors to the modification of metabolism. With the growing number of "omics", new approaches can be used to understand metabolic changes that occur in plants, especially in proteomics and metabolomics, and thus those analyses could be profiled in coming years with the objective of knowing the allelopathome of a larger number of plant species and their interactions. Aim: To provide a recent update on the science of allelopathy in the context of physiology, practical application of metabolomics in allelopathic studies, allelochemicals analyzed by metabolomics in alfalfa, rice, canola, sorghum, rye, wheat and other crops and finally mentionated the biological activity of allelopathic secondary metabolites. Methods: A recent comprehensive literature search of allelopathy and metabolomics in journal databases was carried out. Results: The concept of allelopathy, allelopathic mechanisms, metabolomic studies in allelopathy, allelochemicals analysed by metabolomics in alfalfa, rice, canola, rye sorghum, wheat and other agro-industrially important crops, and the biological activity of allelopathic secondary metabolites are detailed. Conclusions: These studies suggest that a combination of secondary metabolites can be used to attack weeds. In situ and In vitro culture of secondary metabolites (allelochemical types) is recommended to be used as organics compounds in weed organic control in the future. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that of the species studied in the Brazilian Semiarid, the ones most functionally similar to tree Azadirachta indica would be more affected by this exotic species during germination and early development. At first, we produced a crude extract of A. indica fresh leaves in six different dilutions. We placed 25 seeds of four native species (Cenostigma pyramidale, Libidibia ferrea, Mimosa caesalpiniifolia, and Amburana cearensis) to germinate in Petri dishes for each dilution, with four replicates for each species. We assessed: radicle length, emergence percentage, emergence speed index, and mean emergence time. We conducted an experiment in a greenhouse to assess how the exotic plant affected the development of individual plants of the studied species. We planted five seeds of each native species alone and five in interaction with the exotic species using ten 20-l buckets. The experiment lasted four months, and the functional attributes of the individuals were collected. Among the native species analyzed, according to the cluster analysis using the functional attributes of the species planted alone, M. caesalpiniifolia, C. pyramidale and L. ferrea were functionally more similar to the exotic species. In the germination experiment, the extract affected only root length, regardless of the functional similarity. We noticed that only M. caesalpiniifolia had its early development strongly inhibited when planted in interaction with the exotic species. Although the functional similarity between the exotic and the native species did not influence germination, it negatively affected the development. [ABSTRACT FROM AUTHOR]

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Introduction: Cyanobacterial blooms in tropical water bodies are increasingly common, because of eutrophication and rising temperatures. Consequently, many freshwater systems are affected, by reducing water quality, biodiversity, and ecosystem services. With the increased frequency of harmful algal blooms, the development of biological tools to improve water quality is an urgent issue. Objective: To evaluate the effects of a submerged macrophyte and a cladoceran on the microcystin-producing cyanobacteria Microcystis aeruginosa (NPLJ-4) and the chlorophyte Raphidocelis subcapitata (BMIUFRPE-02) in mixed cultures. Methods: Two parallel experiments were carried out for ten days to evaluate the effects of the submerged macrophyte Ceratophyllum demersum and the cladoceran Moina micrura on microalgal interactions. Microalgal strains were cultivated in the ASM1 culture medium, under controlled laboratory conditions. The first experiment presented four treatments: M (C. demersum), Z (M. micrura), MZ (C. demersum and M. micrura), and C (control). Meanwhile, the second experiment consisted of five treatments, in which the microalgae were cultivated together at different Microcystis:Raphidocelis ratios: 1:0, 3:1, 1:1, 1:3, and 0:1. Biomass and growth rates of the strains were evaluated every two days, which were statistically treated with three-way or two-way repeated-measures ANOVA. Results: In the first experiment, M. aeruginosa was significantly inhibited in M and MZ treatments from the second day, and Z from the fourth, while R. subcapitata showed no reduction in its biomass in any treatment. On the other hand, R. subcapitata was stimulated from the eighth and tenth days in M treatment and only on the eighth day in Z treatment. In the second experiment, M. aeruginosa was significantly inhibited when cultivated with R. subcapitata in low ratios (Microcystis:Raphidocelis ratio of 1:3) throughout the experiment, while the chlorophyte was stimulated in that treatment. Conclusions: The coexistence of a cyanobacterium with a green alga did not alter the main negative response of M. aeruginosa to the submerged macrophyte and zooplankton but stimulated the green alga. Accordingly, the introduction of submerged macrophytes and cladocerans already adapted to eutrophic conditions, both isolated and combined, proved to be a good method to control cyanobacterial blooms without negatively affecting other coexisting phytoplankton species. [ABSTRACT FROM AUTHOR]

The vegetable loofah (Luffa cylindrica) has multiple industrial aptitudes and its interaction with allelopathic substances of other species is important for the definition of management strategies and also in the search for control alternatives for invaders in organic crops. The objective of this research was to evaluate the effect of the crude aqueous extract of carqueja (Baccharis articulata) on the germination and growth of seedlings of vegetable loofah. The experimental design used was completely randomized, with four replications and the treatments were composed by the concentrations of carqueja extract (zero, 25, 50, 75 and 100 g L-1 ). Seed germination was tested by the paper roll method with 25 seeds properly spaced over each germination paper. The evaluations were performed at four and fourteen days after the test was installed. The percentage of abnormal seedlings, germination and vigor, length of shoot and roots, dry weight of cotyledons, hypocotyl and roots were evaluated. There was a negative allelopathic effect of the aqueous crude extract from the shoot dry of carqueja plants on germination and vigor and on the growth of seedlings of vegetable loofah. [ABSTRACT FROM AUTHOR]

Allelopathy is a natural phenomenon resulting from the release of substances capable of killing or inhibiting the growth of other plants. Several compounds of medicinal and aromatic plants have allelopathic properties, which may have a beneficial potential in agricultural management, as an alternative to the use in seed treatment, however, they may present some type of allelopathy inhibitory to the development of certain cultures of interest. Therefore, the objective of this work was to evaluate the allelopathic effect of basil oil on germination and on the development of lettuce and arugula seedlings. The experiment was carried out in the seed laboratory of the University Center of Várzea Grande, from September to December 2019. A completely randomized design was used with four treatments (basil oil concentrations - 0; 0.5 %; 1, 0% and 2.0% v v-1) and four repetitions, each repetition consisting of 25 seeds of each vegetable distributed in an acrylic gerbox box with blotting paper. The following characteristics were evaluated: germination at 4 and 7 days; root length and green mass of seedlings. Basil oil has allelopathic stimulatory potential for lettuce seeds in the evaluated concentrations. Basil oil did not affect seed germination, root length and green mass of arugula seedlings. Thus, it can be concluded that the allelopathic effect of basil oil depends on the species studied, and this effect can be positive, negative or neutral depending on the studied concentrations. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the effect of cover crops and fallow duration on the onion crop planted in direct sowing in trials carried out for three years. In the year 2013, two field trials were carried out in two sites. Two cover crops (oats and millet) and one uncovered control were evaluated at three planting dates. The studied variables were crop establishment and dry matter of the cover. In the field trials performed in 2014 and 2015 the effect of the length of the chemical fallow of oats on the establishment of onion was evaluated. The effect of the duration of the chemical fallow of oats was also evaluated in laboratory in 2015 in Petri dishes. In 2013, the greatest establishment was obtained in the treatments without cover in both sites. In 2014 the greater the duration was of the chemical fallow of the cover, the greater the onion establishment. In the field trial in 2015, no effects of fallow duration on crop establishment were observed, a result attributable to the intense rainfall recorded. In the laboratory, germination was higher in treatments with longer fallow periods. Based on the results, evidence was obtained of the negative effect of the cover crops in the establishment of the onion crop. These effects were inversely related to the duration of chemical fallow and may be attributable to allelopathic effects. [ABSTRACT FROM AUTHOR]

The interest in the exploration of compounds from the secondary metabolism is seen as a strategic alternative in agriculture, even for the control of invasive plants. The objective of this work was to measure the allelopathic activity of extracts CHCl3 and AcOEt from the leaves of O. puberula on the germination of lettuce. The ethanolic extract was obtained from the dried and milled leaves. The crude extract was solubilized in ethanol and acidified (hydroalcoholic fraction). The C6H14 fraction was obtained by liquid-liquid extraction of the hydroalcoholic fraction, the same procedure was used to extract the AcOEt fraction. The hydroalcoholic fraction was basified and extracted with CHCl3. The chemical profile of the obtained fractions was analyzed by Thin Layer Chromatography using specific revelators that confirmed the presence of alkaloids as majority compounds in AcOEt and CHCl3 fractions. The fractions were evaluated for allelopathic potential on lettuce cypselas at 0.8 g mL-1, 0.4 g mL-1 and 0.2 g mL-1. In germination tests the germination parameters analyzed were: germination percentage (% G) and germination speed index (IVG). The results indicated significant changes in the %G, IVG and root growth (CR) of the lettuce seeds and seedlings. The ethanolic extract of leaves of O. puberula showed allelopathic influence on the species L. sativa. Both the AcOEt and CHCl3 fractions reduced the germination rates evaluated, and the latter indicated a dose-response inhibition between the treatments applied. [ABSTRACT FROM AUTHOR]

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The purpose of thisstudy was to carry out phytochemical prospecting of Norantea guianensis bark and to evaluate its allelopathic potential in seed germination and the initial growth of lettuce and tomato seedlings using aqueous and ethanolic extracts. We identified phenolic compounds and derivatives, flavonoids, and tannins, as well as coumarins, anthraquinones, alkaloids, and saponins. Negative interference was observed in germination and vigour tests, mainly in tomato seeds, with extracts negatively affecting seedling development. The species N. guianensis has the ability to interfere in the development of other plants, and for this reason, its use should be carefully evaluated. [ABSTRACT FROM AUTHOR]

In the present study we evaluated the chemical composition and allelopathic activity of the essential oil (EO) of Blepharocalyx salicifolius (Kunth) O. Berg leaves on the germination and initial growth of Lactuca sativa L. (dicotyledonous) and Sorghum bicolor (L.) Moench (monocotyledon). EO was obtained by hydrodistillation for 3 h. The EO composition analysis was performed by gas chromatography coupled to a mass spectrometry (GC-MS). The allelopathic activity of EO was evaluated at 2.5; 5.0 and 7.5%. The seeds were immersed in the solution for 2 min., distributed in Petri dishes, that were maintained in a BOD incubator. On the seventh day, the variables germination (%), root length (cm), shoot length (cm) and total seedling length (cm) were evaluated. The major constituents identified in the OE were eucalyptol (49.6%), limonene (13.6%) and β-caryophyllene (12.2%). The EO affected negatively the germination percentage of L. sativa seeds and the root system and total seedling length of S. bicolor. There was a negative allelopathic activity against the two evaluated species. [ABSTRACT FROM AUTHOR]

Soluble allelochemicals have generated great interest since they can be used for the biological control of pests, especially of weeds. However, few studies have evaluated the effectiveness of soluble compounds of exudates on germination in relation to exposure time. Here we evaluate the inhibitory effect of aqueous root, stem and leaf extracts of five South American species of Bothriochloa on the percentage of seed germination of four target species (lettuce, lovegrass, maize and wintergreen paspalum) over three exposure periods (48, 120 and 168 h). Aqueous extracts of the five Bothriochloa species inhibited germination; germination inhibition was strongly correlated with exposure time, with the longest treatment period (168 h) being the one of greatest inhibitory activity. Inhibitory activity differed among types of aqueous extracts. The suitable management of allelopathy might improve crop productivity and environmental protection through biologically friendly control of weeds. [ABSTRACT FROM AUTHOR]

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Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia 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.)

Algumas plantas podem produzir compostos secundários com potencial benéfico no manejo agrícola, como alternativa à utilização no tratamento de sementes, porém, podem apresentar algum tipo de alelopatia inibitória ao desenvolvimento de determinadas culturas de interesse. Logo, o objetivo deste trabalho foi avaliar efeitos alelopáticos do extrato aquoso de manjericão (Ocimum basilicum L.) e babosa (Aloe vera L.) em concentrações na germinação e desenvolvimento inicial de sementes de rúcula (Eruca sativa L.). A concentração para o extrato aquoso foi de 20% (peso/volume) e a partir desta, foram obtidas as demais concentrações. Os tratamentos utilizados foram as concentrações de 25, 50, 75 e 100% dos extratos de babosa e manjericão extraídos pelo método a frio de turbólise, e testemunha com água autoclavada. Os efeitos dos extratos foram avaliados quanto as variáveis: índice de velocidade de germinação, porcentagem de germinação, comprimento de radícula e parte aérea. O experimento foi conduzido em delineamento inteiramente casualizado, com 6 repetições, sendo a unidade experimental composta por uma caixa gerbox com 50 sementes de rúcula. As doses de manjericão e babosa foram testadas em experimentos distintos. Os extratos de manjericão e de babosa apresentam substâncias que favorecem o desenvolvimento da parte aérea, influenciaram negativamente no desenvolvimento da radícula, porém, não apresentaram efeito alelopático na germinação final e velocidade de germinação de sementes de rúcula. [ABSTRACT FROM AUTHOR]

Allelopathy is a strategy of plants to defend and delimit their territory, greatly common in weeds. The snakeweed (Stachytarpheta cayennensis) is a type of weed widely found in cultivation areas and in urban areas in the Brazilian Amazon. Only few researches on allelopathy deal with anatomic changes that secondary metabolites cause on the affected plants. Current paper analyzes the allelopathic activity of five concentrations of the alcoholic extract (0; 0,5; 1; 2; 4%) of S. cayennensis at the level of anatomic changes in Cucumis sativus seedlings. Results evidence an increase in thickness of anatomic structures of the organs in aqueous and alcoholic extracts, revealing pronounced thickness as concentrations of the extract increase. The release of compounds that interfere in the development of C. sativus is an important datum to be employed in the development of alternative strategies instead of herbicides in other cultivations by an ecological management of weed. [ABSTRACT FROM AUTHOR]

Introduction: Use of allelochemicals as inexpensive, biodegradable and eco-friendly substitutes for the management of weeds in crops is a central topic nowadays. Objective: The current study represented the comprehensive screening of allelopathic activity of 73 weeds in Pakistan by the Sandwich method and dish pack method. To investigate the allelochemical compound in top most allelopathic weed. Methods: Allelopathic effects of selected weeds leaves leachate were determined through sandwich technique, while volatile allelopathic effects through dish pack techniques. Qualitative and quantitative phytochemical techniques were applied to investigate allelochemical potential of Melilotus indicus. The statistical analysis of the data described the allelopathic effect of 73 weed plants on lettuce seedling growth in terms of radicle and hypocotyl elongation. Results: Elongation percentage of radicle and hypocotyl ranged 0-74 % to 0-148 % and 0-75 % to 0-84 % respectively at 10 mg concentration of dry plant powder in sandwich method while it was 2-234 % and 7-150 % at in Dish Pack method. Among the plants screened for phytotoxic activity, M. indicus contained the strongest allelochemicals. Qualitative and quantitative analysis of M. indicus showed the presence of flavonoids and phenolic compound along with other allelochemical. Conclusions: Selected weeds may have strong allelochemical potential that can help in the development of bioactive compounds from plant species to be used as natural herbicides and pesticides for sustainable management of weeds and pest. [ABSTRACT FROM AUTHOR]

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Copyright of Revista Colombiana de Ciencias Hortícolas is the property of Revista Colombiana de Ciencias Horticolas 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 seed germination and the early plant growth of corn (Zea mays) and soybean (Glycine max) sowed after cropping and under straw residues (simulating crop rotations) of oat (Avena sativa), ryegrass (Lolium multiflorum) and wheat (Triticum aestivum) were investigated in pot experiments carried out under controlled conditions. The germination rates ranged from 78 to 95% (corn) and from 68 to 97% (soybean), while the speed emergence index ranged from 0.9 to 1.3 (corn) and from 0.7 to 0.12 (soybean). The lowest germination rates and speed emergence indexes occurred in crop rotation for wheat (corn) and ryegrass (soybean). In addition, the highest seedling emergence average time occurred in the crop rotation for wheat (corn) and ryegrass (soybean). On the other hand, the crop rotation for oat affected neither the speed emergence index nor the seedling emergence average time, despite causing a slight reduction of the seed germination (corn and soybean) and the shoot length (corn). Except for the crop rotation for ryegrass (soybean), the total dry mass of corn and soybean reduced when winter crops were previously cultivated. These results suggest that a delay and a reduction of seed germination and seedling emergence can occur in subsequent summer crops, depending on the winter species previously cropped, impacting on the early growth of summer crops. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Applied Technology for Agricultural Science / Revista Brasileira de Tecnologia Aplicada nas Ciências Agrárias is the property of Brazilian Journal of Applied Technology for Agricultural Science 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.)

This study aimed evaluate the efficiency of Cymbopogon citratus essential oil in the sanitary and physiological quality of sorghum seeds of cultivar XB6020. The experiment used sorghum seeds treated with essential oil of C. citratus at concentrations of 0, 0,25%, 0,50%, 1% and 1,5%. The following characteristics were evaluated: seed health by Blotter test method, first germination count, germination and dry mass weight of normal seedlings. The analysis was done using a completely randomized design (DIC) with five concentrations and five replicates, in two separate tests, one to check the sanity and evaluation of physiological quality of the seeds. The essential oil of lemon grass (C. citratus) reduces the infestation of fungi, mainly of Fusarium, however, it may induce the development of Penicillium; and at 1.5% concentration presents a phytotoxic effect reducing the germination and vigor of sorghum seeds. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia 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.)

Copyright of Brazilian Journal of Applied Technology for Agricultural Science / Revista Brasileira de Tecnologia Aplicada nas Ciências Agrárias is the property of Brazilian Journal of Applied Technology for Agricultural Science 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.)

Due to its economic, social, and ecological potentials, yerba mate can be a source of employment and income in the southern region of Brazil. The objectives of the present study was to (1) quantify the total polyphenols in fresh yerba mate seeds (FS), seeds dehydrated for 70 d (SD), and seeds stratified in sand for 180 d (SS); (2) evaluate the potential germination and growth inhibitory effects of water, ethanol + water (1:1), and ethanol (99%) extracts of yerba seeds (FS, SD, and SS) using lettuce seedlings; and (3) verify the presence of polyphenols in fresh seeds of yerba mate through histochemical methods. In the bioassay, extracts of yerba mate seeds were used in the germination of lettuce seeds. For the histochemical analysis, sections of yerba mate seeds were stained with specific dyes. The results revealed that yerba mate fresh seeds contain higher concentration of phenolic compounds, which decreased in dehydrated seeds, and almost no phenolic compound was observed in stratified seeds. The bioassay results showed that the polyphenols present in the extracts of yerba mate seeds resulted in phytotoxic effect on the roots of lettuce seedlings. The histochemical observations revealed the presence of "lignified rough barrier" and phenolic compounds between the endocarp and endosperm of the yerba mate seeds. [ABSTRACT FROM AUTHOR]

Some exotic species threat the integrity of natural environments due to their invasive potential. They can affect other species by releasing secondary compounds in the soil. Morus nigra (Moraceae) is an invasive species of riparian forests in southern Brazil. The objective of this study was to verify if the aqueous extracts of fruit, fresh and dry leaves of M. nigra show phytotoxic effects on germination, seedling growth and membrane integrity of seedlings of Lactuca sativa. Extract concentrations of 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5 and 10% were tested. Germination rate and speed of germination were determined. Effects on initial growth were evaluated by measuring seedling root and shoot length, and membrane integrity was assessed by conductivity tests. Results showed the phytotoxicity of M. nigra aqueous extracts, causing significant inhibition on germination and seedling growth. The fruit extract was generally less phytotoxic than extracts from fresh and dry leaves. Moreover, the extracts induced changes in membrane integrity and caused morphological deformities in seedlings, such as necrotic roots and chlorotic plants. The high phytotoxicity of fruit, dry and fresh leaf extracts of M. nigra was evidenced, indicating the allelopathic potential of the species. [ABSTRACT FROM AUTHOR]

This study aimed to verify the possible allelopathic activities of aqueous extracts obtained from stem and roots of Pilosocereus catingicola (Gürke) Byles & Rowley subsp. salvadorensis (Werderm.) Zappi (Cactaceae) on seed germination of the species itself. For this, stem and root aqueous extracts of P. catingicola subsp. salvadorensis were produced. The aqueous extracts were tested at concentrations of 0% (distilled water), 25%, 50%, 75% and 100% obtained by dilution in distilled water. Germinability (%) and the mean germination time (days) were evaluated. The results were submitted to analysis of variance in STATISTICA 13 program. Seeds germinability was negatively affected by the aqueous extract obtained from the stem. Although it did not significantly affect seeds germinability, root aqueous extract increased seeds mean germination time. Stem aqueous extract also increased mean germination time in all evaluated concentrations. P. catingicola subsp. salvadorensis produces substances that have allelopathic effects, which negatively affect seed germination of the species itself. [ABSTRACT FROM AUTHOR]

Copyright of Revista Ceres is the property of Revista Ceres 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.)

Copyright of Nativa is the property of Revista Nativa 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.)

Copyright of Cientifica is the property of Fundacao de Apoio a Pesquisa e Extensao 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.)

Copyright of Nativa is the property of Revista Nativa 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.)

As an option for the problem of agrotoxics, agroecology has sought the control of spontaneous species through the use of parts of plants with herbicidal activity. The following work consists of a bibliographical research that aims to gather the information disseminated in several articles on the biodiversity of medicinal plants as natural herbicides. For the review of the literature, it was decided to search for articles in national and international journals during the period from 1997 to 2014. Several studies that cover medicinal plants were observed in the literature, but the evaluation of allelopathic potential is limited. The study added medicinal plants that possess potential secondary allelopathic compounds, with the possibility of being used in the production of natural herbicides. It is important to encourage this type of studies, for an ecological perspective in general, to enable the manipulation of allelopathic interactions related to agriculture. [ABSTRACT FROM AUTHOR]