Growth Of Lactuca Sativa Research Articles

Bioguided fractionation and isolation of phytotoxic compounds from Apium graveolens L. aerial parts (Apiaceae)

The phytotoxic activity of celery (Apium graveolens L.) was tested on germination and seedling growth of Lactuca sativa (lettuce). Bioactive compounds were isolated and identified by spectral data. Methanol extract of celery aerial part showed a significant phytotoxic effect on lettuce. Thus, this extract was divided into hexane and methanol fractions. Bioassay-directed of these two fractions led to the isolation and characterization of six secondary metabolites which included three phthalides (senkyunolide A, (3S)-butylphthalide and sedanolide), two furanocoumarins (bergapten and scopoletin) and one phenylpropanoid (p-hydroxyphenethyltrans-ferulate). Among these compounds, senkyunolide A was the most toxic on lettuce germination and shoot growth. However, p-hydroxyphenethyl trans-ferulate was the most toxic on root growth.

Lactuca sativa growth in compacted and non-compacted semi-arid alkaline soil under phosphate fertilizer treatment and cadmium contamination

Soil compaction is known to drastically modify soil properties and hence to affect both plant growth and metal distribution in the soil. Phosphate amendment is generally used to improve plant production but unfortunately it also gives rise to higher metal contamination in soils and plants. In this work, we aimed to study the effects of soil density, phosphate fertilization and cadmium contamination on the growth of Lactuca sativa. In particular, the migration of cadmium in the soil columns, its accumulation and translocation in lettuce were also examined. Lactuca sativa was selected as a model plant because it is widely cultivated in alkaline clay soils of eastern Mediterranean countries. Two levels of soil compaction (1.2 and 1.4gcm−3), two rates of P amendment (0 and 109mg Pkg−1), and two levels of Cd contamination (0 and 84mg Cdkg−1) were used in 24 model columns with a factorial randomized block experimental design. Soil compaction increased considerably both leaf area and dry weight of roots and shoots, whereas both chlorophyll content and NRA decreased. For the two soil bulk densities, the phosphate fertilizer improved lettuce growth characterized by plant height, dry matter, leaf number and NRA, whereas Cd contamination altered those parameters and increased the chlorophyll content. In soils contaminated with cadmium, the combination of compaction and phosphate fertilization resulted in a significant decrease in Cd migration along the soil columns. Cd uptake by plants increased in Cd treated soils; its accumulation was found to be more important than in plants grown in P-Cd treated soil where Cd uptake was clearly reduced in shoots and roots.

The allelopathic effects of invasive plant Solidago canadensis on seed germination and growth of Lactuca sativa enhanced by different types of acid deposition.

Invasive species can exhibit allelopathic effects on native species. Meanwhile, the types of acid deposition are gradually changing. Thus, the allelopathic effects of invasive species on seed germination and growth of native species may be altered or even enhanced under conditions with diversified acid deposition. This study aims to assess the allelopathic effects (using leaves extracts) of invasive plant Solidago canadensis on seed germination and growth of native species Lactuca sativa treated with five types of acid deposition with different SO4(2-) to NO3(-) ratios (1:0, sulfuric acid; 5:1, sulfuric-rich acid; 1:1, mixed acid; 1:5, nitric-rich acid; 0:1, nitric acid). Solidago canadensis leaf extracts exhibited significantly allelopathic effects on germination index, vigor index, and germination rate index of L. sativa. High concentration of S. canadensis leaf extracts also similarly exhibited significantly allelopathic effects on root length of L. sativa. This may be due to that S. canadensis could release allelochemicals and then trigger allelopathic effects on seed germination and growth of L. sativa. Acid deposition exhibited significantly negative effects on seedling biomass, root length, seedling height, germination index, vigor index, and germination rate index of L. sativa. This may be ascribed to the decreased soil pH values mediated by acid deposition which could produce toxic effects on seedling growth. Sulfuric acid deposition triggered more toxic effects on seedling biomass and vigor index of L. sativa than nitric acid deposition. This may be attributing to the difference in exchange capacity with hydroxyl groups (OH(-)) between SO4(2-) and NO3(-) as well as the fertilizing effects mediated by nitric deposition. All types of acid deposition significantly enhanced the allelopathic effects of S. canadensis on root length, germination index, vigor index, and germination rate index of L. sativa. This may be due to the negatively synergistic effects of acid deposition and S. canadensis on seed germination and growth of L. sativa. The ratio of SO4(2-) to NO3(-) in acid deposition was an important factor that profoundly affected the allelopathic effects of S. canadensis on the seed germination and growth of L. sativa possibly because the difference in exchange capacity with hydroxyl groups (OH(-)) between SO4(2-) and NO3(-) as well as the fertilizing effects triggered by nitric deposition. Thus, the allelopathic effects of invasive species on seed germination and growth of native plants might be enhanced under increased and diversified acid deposition.

Inconsistency in the detection of phytotoxic effects: A test with Acacia dealbata extracts using two different methods

The phytotoxic activity of novel natural compounds is generally evaluated by the bioassay-directed fractionation procedure conducted with bioassays on model species. Two different methodologies to dissolve the examined compounds, using either organic solvents and water, or dimethyl sulfoxide (DMSO) and buffered medium, are commonly used in these bioassays. However, whether the bioactivity of tested compounds is the same under those different conditions remains unexplored. To elucidate this, we designed a study to compare the activity of chemical compounds extracted from the allelopathic Acacia dealbata using different solvents. Natural compounds from flowers, leaves and bark were fractionated with hexane, ethyl acetate and water and bioassayed using either these solvents or a common DMSO-buffer medium for the three fractions. The effect of these compounds on the germination and seedling growth of Lactuca sativa was subsequently tested using a common bioassay design. The type of dissolving method had a significant effect on the bioactivity of A. dealbata compounds. In general, phytotoxic activity is increased by DMSO-Buffer Bioassays. A higher number of phytotoxic effects of hexane and ethyl acetate compounds were also found in DMSO-Buffer Bioassays. Conversely, polar compounds present in the water fractions showed more significant effects when dissolved just in water. On the other hand, polar compounds obtained from A. dealbata leaves significantly and consistently inhibited the radicle length of L. sativa with both methods, suggesting a potential bio-herbicide activity for these compounds. We conclude that the phytotoxic activity of low- or intermediate-polar compounds should be evaluated using DMSO-Buffer Bioassays while Water Bioassays seem to be more appropriate for testing the biological activity of compounds soluble in water.

Phytotoxicity and Cytotoxicity of Essential Oil from Leaves of Plectranthus amboinicus, Carvacrol, and Thymol in Plant Bioassays.

The essential oil of Plectranthus amboinicus and its chemotypes, carvacrol and thymol, were evaluated on the germination and root and aerial growth of Lactuca sativa and Sorghum bicolor and in acting on the cell cycle of meristematic root cells of L. sativa. The main component found in the oil by analysis in gas chromatography-mass spectrometry and gas chromatography flame ionization detection was carvacrol (88.61% in area). At a concentration of 0.120% (w v(-1)), the oil and its chemotypes retarded or inhibited the germination and decreased root and aerial growth in monocot and dicot species used in the bioassays. In addition, all substances caused changes in the cell cycle of the meristematic cells of L. sativa, with chromosomal alterations occurring from the 0.015% (w v(-1)) concentration. The essential oil of P. amboinicus, carvacrol, and thymol have potential for use as bioherbicides.

Investigation of biochemical and competitive effects of cover crops on crops and weeds

The weed suppressing ability and growth of 17 cover crops and undersown crops was evaluated in eleven pot and laboratory experiments. Weed suppression was greater using mulched cover crops than with undersown crops. Mulched cover crops had no effects on biomass of Hordeum vulgare and undersown crops decreased Triticum aestivum biomass in the pot experiments. Biochemical effects of various concentrations of aqueous cover crop root- and shoot-extracts were determined in the laboratory. Observed effects were inhibitory, hormetic, or combined on root growth of Lactuca sativa, Setaria viridis, Amaranthus retroflexus and Zea mays. Nonlinear dose–response functions fitted best to the data; more pronounced inhibitory effects occurred with highly concentrated plant extracts. Festuca rubra, Avena strigosa and Cannabis sativa were the cover crop species with the strongest inhibiting biochemical effect on L. sativa, maize and weeds. Active compounds and mode of action of biochemical are unknown and biochemicals from cover crop residues require research under field conditions.

Low Concentrations of Humic Substances Enhanced the Growth of Lactuca sativa L.

Low Concentrations of Humic Substances Enhanced the Growth of Lactuca sativa L.

Avaliação alelopática de extratos etanólicos de Copaifera sabulicola sobre o desenvolvimento inicial de Lactuca sativa, Lycopersicum esculentum e Zea mays

This paper aimed to evaluate the allelopathic potential of ethanol extracts from stem and leaves of Copaifera sabulicola on seed germination and seedling growth of Lactuca sativa and Lycopersicum esculentum, as well as to evaluate the allelopathic effect of these extracts on seedling germination and growth of Zea mays, through bioassays under laboratory conditions. The extracts were tested at the concentrations 0, 250, 500, and 1,000 mg.L-1. We evaluated the germination percentage, germination average speed, germination speed index, and seedling average length. All parameters underwent variance analysis, and the mean values were compared by means of Scott-Knott test (p ≤ 0.05). We found out that, in L. sativa, the extract from stem promoted significant stimuli on germination percentage and root growth, while the extract from leaves only stimulated root growth. In L. esculentum, the extract from stem promoted significant stimulus on hypocotyl and root growth, in turn, the extract from leaves stimulated only root growth. In Z. mays, both extracts significantly inhibited germination. Therefore, we found out the allelopathic potential of ethanol extracts of C. sabulicola on L. sativa and L. esculentum, as well as inhibitory allelopathic effect on Z. mays.

Growth Effects of Pb stress on Seedling of <i>Lactuca sativa</i> L. and <i>Brassica campestris</i> L.ssp

In order to understand the effects of lead on the growth of Lactuca sativa L. and Brassica Campestris L. ssp, the change of growth index of seedling was studied under lead stress (different concentrations of lead nitrate solution), and by soilless cultivation of seedlings in pots and in greenhouse. The results showed that two kinds of plant growth were affected by lead stress of different level, the growth speed of seedlings reduced but a great number of growth index were increased, in addition to fresh weight and dry weight of stem and leaf. The leaf number, leaf area, plant height and the fresh weight, dry weight of stem and leaf in Lactuca sativa L. were declined obviously, and the fresh weight, dry weight of roots were increased under higher levels of lead treatment at the same time. The each growth index of Brassica Campestris L.ssp was decreased in higher concentration of lead treatment. The growth of Lactuca sativa L. was slightly better and Brassica Campestris L. was slightly lower than control under 0.005 mg/L lead treatment. So, Lactuca sativa L. wasmore sensitive in low concentrations of lead than Brassica Campestris L. Both of them reduced their growth significantly, especially Brassica Campestris L.in 0.015 mg/L lead treatment. Each grow index of Lactuca sativa L.and Brassica Campestris L. changed most in all kinds of lead concentration, and the growth was inhibited most in 0.045 mg/L lead. The growth of Brassica Campestris L.was decreased more under higher concentrations of lead compared with Lactuca sativa L..

Fitotoxicidade e citogenotoxicidade da água e sedimento de córrego urbano em bioensaio com Lactuca sativa

Objetivou-se, com este trabalho, avaliar a influência espacial e temporal da fitotoxicidade e da citogenotoxicidade da água e do sedimento de córrego urbano quanto às características germinativas e de crescimento inicial de Lactuca sativa. Amostras de água e de sedimento foram coletadas em 5 pontos do Córrego do Pântano (Alfenas, Minas Gerais), no período de outubro de 2010 a julho de 2011 e as concentrações dos metais Cd, Pb e Zn foram quantificadas. Os ensaios de fitotoxicidade e de citogenotoxicidade foram realizados com as amostras de água e extratos aquosos dos sedimentos. Os parâmetros avaliados foram taxa de germinação, comprimento de raízes, biomassa fresca e seca, índice mitótico e a frequência de anormalidades cromossômicas. Constataram-se maiores concentrações de Cd e Pb nas amostras de água coletadas nos meses com a ocorrência de precipitações pluviométricas. Água e sedimento apresentaram efeito fitotóxico sobre germinação, biomassa fresca e seca de Lactuca sativa. O comprimento de raízes foi estimulado e apenas as amostras de água reduziram o índice mitótico. Evidenciou-se, também, variação temporal significativa relacionada com o regime pluviométrico apenas para o teste de fitotoxicidade.

Phytotoxic activity and metabolism of Botrytis cinerea and structure-activity relationships of isocaryolane derivatives.

Research has been conducted on the biotransformation of (8S,9R)-isocaryolan-9-ol (4a) and (1S,2S,5R,8S)-8-methylene-1,4,4-trimethyltricyclo[6.2.1.0(2,5)]undecan-12-ol (5a) by the fungal phytopathogen Botrytis cinerea. The biotransformation of compound 4a yielded compounds 6-9, while the biotransformation of compound 5a yielded compounds 10-13. The activity of compounds 4a and 5a against B. cinerea has been evaluated. (8R,9R)-Isocaryolane-8,9-diol (6), a major metabolite of compound 4a, shows activity compared to its parent compound 4a, which is inactive. The effect of isocaryolanes 3, 4a, and 5a, together with their biotransformation products 6-8, 10, and 14-17, on the germination and radicle and shoot growth of Lactuca sativa (lettuce) has also been determined. Compounds 7-13 are described for the first time.

Comparative allelopathic effects of Cryptocarya moschata and Ocotea odorifera aqueous extracts on Lactuca sativa

The aim of this work was to compare the allelopathic effects of aqueous leaf extracts from Cryptocarya moschata and Ocotea odorifera on the seed germination and initial growth of Lactuca sativa (lettuce). The extracts were prepared by cold maceration, which was accomplished by adding distilled water to the dried plant material 1:10 (w v-1) and grinding. The treatment concentrations (0, 0.25, 0.5, 0.75 and 1%) were obtained by dissolving the dried crude extract in distilled water. The allelopathic potential of the dried Ocotea odorifera and Cryptocarya moschata leaves on Lactuca sativa was observed through reduction of the percentage of seeds that germinated, the index of germination and the length of the roots as well as structural abnormalities in L. sativa seedlings. For both extracts, the extract concentration and allelopathic effect were highly correlated. However, the C. moschata extract had no effect on caulicle length at the different tested concentrations.

Allelopathic and bioherbicidal potential of Cladonia verticillaris on the germination and growth of Lactuca sativa

Responses to germination and initial growth of Lactuca sativa (lettuce) submitted to organic extracts and purified compounds of Cladonia verticillaris (“salambaia”) were analyzed in this work. The experiments were conducted in laboratory conditions using extracts and pure compounds at different concentrations. None of the assays showed any influence on the germination of L. sativa seeds using C. verticillaris extracts; however, modifications in leaf area and seedling hypocotyl and root development occurred. In the growth experiments, seedlings exposed to ether or acetone extract showed diminished hypocotyl growth in detriment to the root stimulus, compared to controls. Increases in extract concentrations led to the formation of abnormal seedlings. To determine the allelochemicals of C. verticillaris, its principal components, fumarprotocetraric and protocetraric acids, were isolated and then analyzed by high performance liquid chromatography (HPLC). When the seedlings were exposed to the two acids separately, presented increased leaf area at all concentrations. In contrast, hypocotyl and root stimulus was observed only in the presence of protocetraric acid at different concentrations. Fumarprotocetraric as well as protocetraric acids, isolated and purified from C. verticillaris and Parmotrema dilatatum respectively, influenced the development of L. sativa seedlings at high concentrations, indicating a possible bioherbicide potential of these acids.

Phytotoxic activity in Flourensia campestris and isolation of (−)-hamanasic acid A as its active principle compound

An aqueous extract from Flourensia campestris (Asteraceae) dry aerial parts showed strong inhibition on the germination and growth of Lactuca sativa. Based on bio-guided chromatographic fractionation of aq. extracts from dry and fresh leaves and spectroscopic means, (-)-hamanasic acid A (7-carboxy-8-hydroxy-1(2), 12(13)-dien-bisabolene (1)) was isolated as the most inhibitory active principle on germination (ECg50=2.9mM) and on root (ECr50=1.5mM)/shoot (ECs50=2.0mM) growth. As measured by GC, and correlated with a simple designed 2D-TLC, compound 1 was distributed throughout the plant, with a remarkably high concentration (1.6%) in the leaves and the inflorescences. At least a quarter of the amount of 1 was found in aqueous extracts suggesting that leaching would be a key route for its release into the environment. By contrast, leaf essential oils (HD) between 0.5 and 1.5μlml−1 did not show herbicidal effects and 1 was not found in them (TLC) nor among volatiles (HS-SPME). Volatile compositions were assessed by GC-FID and GC–MS and led to the identification of 23 compounds (4 monoterpenes and 19 sesquiterpenes) with a wide seasonal (spring–summer%) variation, represented principally by bicyclo-germacrene (37–6%), spathulenol (4–32%), globulol (20–0%), beta-caryophyllene (15–6%), caryophyllene oxide (1–13%) and bicycloelemene (10–1%), respectively. The high amount of 1 in F. campestris together with its feasibility of being extracted with water suggest that (−)-hamanasic acid A is an allelochemical in this species. Species-specific studies must be carried out to evaluate the potential of 1 as a natural herbicidal compound.

Allelopathic interference of Sapindus saponaria root and mature leaf aqueous extracts on diaspore germination and seedling growth of Lactuca sativa and Allium cepa

Sapindus saponaria (soapberry) is a species that presents a great diversity of chemical compounds, such as saponins; however, few studies have examined the allelopathic effect of this species. Therefore, this study provides an evaluation of the allelopathic potential of aqueous extracts of the roots and mature leaves of S. saponaria on the germination of diaspores and seedlings growth of lettuce (Lactuca sativa) and onion (Allium cepa). The aqueous extract was prepared in the proportion of 100 g of dry plant material in 1,000 mL of distilled water (a concentration of 10% w v-1), and diluted with distilled water to 7.5, 5.0 and 2.5% concentrations. The mature leaf extracts caused delay and decrease in the germination process of the lettuce and onion diaspores, with inhibitory effect concentration-dependent, while the root extracts showed no allelopathic effects on the germination process. Both extracts caused abnormalities and inhibited the growth of shoot and root seedlings.

Allelopathic interference of Sapindus saponaria root and mature leaf aqueous extracts on diaspore germination and seedling growth of Lactuca sativa and Allium cepa

Allelopathic interference of Sapindus saponaria root and mature leaf aqueous extracts on diaspore germination and seedling growth of Lactuca sativa and Allium cepa

Chemical Composition and Bioactivity of Acantholippia seriphioides Essential Oils from Patagonia

The aerial parts of Acantholippia seriphioides (A. Gray) Mold. were collected from three sites in the neighborhood of Comodoro Rivadavia, in Patagonia (Astra, Saavedra and Rada Tilly), and their essential oils were analyzed by GC-FID/MS. Results obtained by the analysis indicated chemovariability in the oils from these sites when matched with other sites. Monoterpene hydrocarbons (92.6–95.1%) were the main group of constituents in all populations, mainly thymol (33.7–38.5%) p-cymene (26.5–35.3%) and γ-terpinene (8.3–12.7%). Essential oils were submitted to biological assays in order to assess their general toxic activity on Artemia salina, and the inhibition effects in the germination and seedling growth of Lactuca sativa. Saavedra sample, associated with greater limonene, carvone, carvacrol and p-cymene contents, was the most active to the A. salina test (LD50 = 23,08 μg/mL−1). Astra sample, associated to a greater relative proportion of γ-terpinene, thymol methyl ether and neral, was the most active to the germination and seedling growth test (IC50=1.86 μg/mL−1). Saavedra sample also showed high activity (IC50= 37.53 μg/mL−1). The bioactivities were not proportional to the content of present active monoterpenes

Potencial fitotóxico de Dicranopteris flexuosa (Schrad.) Underw. (Gleicheniaceae)

O objetivo deste trabalho foi determinar o potencial fitotóxico do extrato etanólico bruto e das frações semipurificadas de Dicranopteris flexuosa por meio de bioensaios de germinação e crescimento de Lactuca sativa L. (alface), Lycopersicon esculentum L. (tomate), Allium cepa L. (cebola) e Triticum aestivum L. (trigo) em laboratório e casa de vegetação e quantificar o teor total de fenóis e flavonóides dos extratos e frações. Nos bioensaios realizados em laboratório foram utilizadas quatro concentrações (0, 250, 500, 1000 mg L-1), com quatro repetições de 50 sementes. A análise dos resultados indica redução da velocidade e/ou inibição da germinação, estímulo do crescimento da raiz das eudicotiledôneas e inibição da raiz adventícia das monocotiledôneas estudadas. Nos bioensaios realizados em casa de vegetação foram utilizadas as mesmas concentrações dos bioensaios em laboratório, com oito repetições de cinco sementes por vaso. A análise dos resultados indica que o comprimento da raiz foi afetado pelo extrato etanólico bruto, ocorrendo estímulo em tomate e inibição em cebola e trigo. A produção de massa seca da parte aérea foi estimulada na menor concentração em alface e trigo. A fração acetato de etila foi a que apresentou os maiores teores de fenóis e flavonóides totais. Embora os resultados sejam preliminares, observa-se que o extrato etanólico e as frações semipurificadas de D. flexuosa também contêm substâncias que interferem no crescimento das plântulas de alface, tomate, cebola e trigo.

Isolation and biological activities of lyoniside from rhizomes and stems of Vaccinium myrtillus

A lignan glycoside identified as lyoniside (9- O-β- d-xylopyranosyl(+)lyoniresinol) was obtained from ethanol extracts of the rhizomes and stems of bilberry ( Vaccinium myrtillus L.), on a preparative scale, by droplet counter-current chromatography. The application of this method permitted the isolation of a pure substance in only one chromatographical step. The occurrence of lyoniside in bilberry is reported for the first time. Seasonal fluctuations in the content of this compound in plant organs were demonstrated showing its highest levels in bilberry rhizomes and stems during the winter and their subsequent decrease in the spring. In vitro, the purified lyoniside was evaluated for antioxidant, allelopathic and antifungal activities. It showed significant radical scavenging properties in a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay with IC 50 of 23 μg ml −1. Applied at concentration of 10 μg ml −1, it suppressed by 75% the seedling radical growth of Lactuca sativa and Lepidium sativum, and exerted strong inhibitory effect (55%) on germination of Larix decidua. Moreover, the synergistic action of lyoniside and triterpene acids was demonstrated in inhibitory effect exerted on germination and growth of Pinus sylvestris. Among 5 tested fungi strains of Ascomycota, the highest susceptibility was shown by Fusarium oxysporum and Mucor hiemalis, with mycelial growth inhibited by lyoniside concentration of 50 μg ml −1 by 78 and 80%, respectively.

Bryophytes display allelopathic interactions with tree species in native forest ecosystems

Bryophytes are widespread in terrestrial ecosystems but little is known about their influence on vascular species. Water‐soluble leachates (0%, 1%, 5%, 10% concentration) derived from 18 species of bryophytes (mosses 11 species; liverworts 7 species) were tested on the germination and seedling growth ofLactuca sativaand two common treesMelicytus ramiflorus(Violaceae) andFuchsia excorticata(Onagraceae) in southern New Zealand forests. Bryophyte water soluble extracts (BWSE) have minor impact on seed germination ofLactuca, stimulatory effects on radical growth at low (1%) concentrations and inhibitory effects at higher concentrations (5–10%). ForMelicytusthe BWSE had variable effects, with evidence of strong stimulatory (Dendrohypopterygium filiculiforme) and inhibitory (Lepidozia concinna) effects on germination, but generally inhibited radical growth. BWSE at all test concentrations consistently inhibit both germination and seedling radicle growth inFuchsia. The toxicity effect of water‐soluble leachates varies significantly between bryophyte species but not consistently between mosses and liverworts. Bryophyte species exhibiting strongest inhibition effects under control conditions were associated with significantly reduced densities of broadleaved tree seedlings in forest ecosystems. Our results demonstrate that some bryophyte species via allelopathic interactions can inhibit seedling establishment and growth of forest trees. This mechanism provides an additional factor constraining the spatial distribution of the regeneration niche in forest communities.