Total Inhibition Of Germination Research Articles

Essential oils from Anethum graveolens L. and their phytotoxic and antibiofilm potential

Essential oils (EOs) from inflorescences (EO-i), stems (EO-s) and leaves (EO-l) of Anethum graveolens are analyzed by GC and GC-MS. The main components are α-phellandrene (51.44%) and p-cymene (22.65%) in the EO-i, p-cymene (50.75%) and α-phellandrene (35.73%) in EO-s and p-cymene (40.01%) and α-phellandrene (36.38%) in EO-l. The phytotoxic activity was tested against germination and growth of aerial parts and roots of dicotyledones (Sinapis arvensis and Trifolium campestre) and monocotyledone (Lolium multiflorum) weeds. The EOs proved to be particularly active against S. arvensis and T. campestre, causing total inhibition of germination and growth at the highest doses (2.0 and 1.5 μL/mL) with IC50 values included between 0.3 and 1.6 mg/mL. The antibacterial and antibiofilm activity was tested against Gram positive (Staphylococcus aureus subsp. aureus and Listeria monocytogenes) and Gram negative (Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli) pathogenic bacterial strains. EOs presented MICs lower than those of Tetracycline (20-24 mg/mL) against most bacterial strains (from 4 to 6 mg/mL). EOs were found to be active in inhibiting bacterial biofilm formation with IC50 values between 1.47 and 3.85 mg/mL. The activity against bacterial metabolism occurred for EO-i and EO-s against A. baumannii and E. coli with IC50 between 0.99 and 5.39 mg/mL. This investigation provides data about the chemical variation among different parts of A. graveolens and encourages the use of its EOs as natural phytotoxic and antibacterial agents in agriculture, food and pharmaceutical sectors.

Effects of Chemical Priming on the Germination of the Ornamental Halophyte Lobularia maritima under NaCl Salinity

Lobularia maritima or sweet alyssum (Brassicaceae) is an annual littoral halophyte, naturally thriving on sandy beaches. In addition to its obvious interest as a naturally salt-tolerant plant, this species is mainly cultivated as an ornamental plant in many countries. Laboratory experiments were carried out to assess the effects of salinity on seed germination and on germination recovery from the effects of saline conditions after transfer to distilled water. Seed germination responses were determined at 0, 50, 100, 200 and 300 mM NaCl. Salt (NaCl) does not affect the germination of L. maritima if applied at a moderate dose of 50 mM. For higher concentrations of NaCl, there is a decrease in the germination rate at 100 and 200 mM NaCl or even a total inhibition of germination at 300 mM. Salt lowers or inhibits germination only through osmotic effects. To improve the germination of L. maritima under high salinity, seeds were pretreated with KNO3, thiourea, proline and salicylic acid. The germination of seeds is improved by KNO3 in the presence or absence of salt, while thiourea increases the final germination without affecting the germination rate. Salicylic acid amplifies the effect of salt, while proline delays germination without stopping it completely. These findings indicate that the application of KNO3 and thiourea may be used to improve seed germination of L. maritima, which is of great interest for cultivating this plant for landscaping purposes in saline soils.

Analysis of Volatiles in Senecio anteuphorbium Essential Oil with a Focus on Its Allelopathic Effect by Means of Gas Chromatography

The present study aimed to investigate Senecio anteuphorbium, an endemic plant growing in West Morocco and widely used in local folk medicine. The essential oil (EO) extracted from the aerial parts was analyzed by gas chromatography and tested for allelopathic activity. The quantitation of the volatiles was carried out by means of GC-FID with response factors, which were validated through reliable calibration procedures, based on external and internal standardization. This analytical approach allowed to define the real concentration of each constituent (weight%, g/100 g) alongside the conventional relative percent. On the other hand, the identification process was supported by a dual matching based on both mass spectra and retention indices. The essential oil resulted in being rich in sesquiterpenes, with the predominant constituents being bicyclogermacrene (22.75 g/100 g), spathulenol (25.26 g/100 g), epi-γ-eudesmol (6.8 g/100 g), and selina-4,11-diene (5.08 g/100 g). The allelopathic effect was evaluated by studying the inhibition of the germination and growth of Lactuca sativa seeds. A potent allelopathic effect was recorded by the essential oil at a dose of 0.281 mg/mL, with almost a total inhibition of germination.

Prediction and evaluation of allelopathic plants species in Algerian Saharan ecosystem

Allelochemicals involved in plant-plant interaction (Allelopathy) are a potential source for alternative agrochemicals to solve the negative effects caused by synthetic herbicides. The present study is focused on the prediction and evaluation of allelopathic plants species in Saharan ecosystem from the Souf region in the southeastern of Algeria. The study was articulated through three steps of investigation: (1) a floristic survey, including a general inventory with notation of abundance and sociability scores for each species to understand the floristic composition of the study area, (2) Species co-occurrence analysis, using a presence/absence of data species in restricted sampling plots, which allowed to identify eight negatively associated species pairs with only one positive association and (3) allelopathic bioassays were performed with the aqueous extracts of the three species negatively associated species. The results showed a significant effect of aqueous extracts of Halocnemum strobilaceum (Pall.) M. Bieb, Retama raetam Forssk. Webb and Limoniastrum guyonianum Boiss on seed germination or seedling growth of target species (Lactuca sativa L., Daucus carota L., Triticum durum Desf. and Zea mays L.) at concentrations of 10 % and 15 %. H.strobilaceum showed the highest phytotoxic activity with 0% germination rate of all target species at concentration of 15 %, followed by R. raetam and L. guyonianum, and D. carota was the most sensitive target species with total inhibition of germination in most of treatments. Besides, plumule length was most affected then radicle length. It was conducted that some of these extracts may be represent a promising alternative bioherbicides from Saharan plants in agricultural and environmental management.

Effect of seawater irrigation on germination and seedling growth of Carob tree (Ceratonia siliqua L.) from Gouraya National park (Béjaïa, Algeria)

The carob tree (Ceratonia siliqua L.) is an important component of the Mediterranean vegetation and its cultivation is important environmentally and economically. It is also an interesting leguminous species for afforestation-reforestation. In this study, carob seeds collected in a representative area of the Mediterranean basin at the national park of Gouraya (Béjaïa, Algeria), were subjected to germination tests under Mediterranean seawater (SW) irrigation of different concentrations (0, 10, 30, 50 and 100% SW) for 15-day period. Before germination tests, a 20 min pre-treatment with 96% sulphuric acid was necessary to overcome seed coat dormancy which does not permit germination. Results showed that the seeds of C. siliqua were able to germinate at different seawater concentration, except for 50% SW and 100% SW which resulted in total inhibition of germination. The maximum number of C. siliqua seed germination of 100% FGP (final germination percentage) appeared at 0% SW and 10% SW. Only 35.5% of the seeds have germinated in 30% SW. Ungerminated seeds of C. siliqua from different SW treatments showed medium germination recovery (FGPRecov) of 39.9% at 50% SW and low recovery of 18.2% at 100% SW when transferred to distilled water after 15 day-period. Seedlings length and seedling fresh and dry weight were significantly (P < 0.001) decreased with increasing SW concentrations. Seedling water content remained constant in 10% SW in comparison with the control, while it decreased very slightly in 30% SW. These findings may serve as useful information for C. siliqua habitat establishment and afforestation-reforestation programs in coastal sites and for exploiting seawater in the area.

Evaluation of the impact of different alkyl length and type of substituent in imidazolium ionic liquids on cucumber germination, growth and oxidative stress.

In this work, the effect on cucumber growth of seven different imidazolium-based ionic liquids, namely 1-(2-oxybutyl)-3-methylimidazolium chloride, [C2OC2mIm][Cl]; 1-(2-oxypropyl)-3-methylimidazolium chloride, [C1OC2mIm][Cl]; 1-(3-hydroxypropyl)-3-ethylimidazolium chloride, [OHC3eIm][Cl]; 1-(3-hydroxypropyl)-3-methylimidazolium chloride, [OHC3mIm][Cl]; 1-(2-hydroxyethyl)-3-methylimidazolium chloride, [OHC2mIm][Cl], 1-butyl-3-methylimidazolium chloride, [bmim][Cl] and imidazolium chloride, [Im][Cl], were examined. The influence of polarity of the alkyl side chain of the imidazolium cation on the reduction of the ionic liquid's toxicity is investigated. For all investigated seedlings, significant reduction of biomass was noted, with the incoherent influence of the ionic liquid (IL) concentration. The total inhibition of germination was shown at the highest used concentration for some of the used ionic liquids. Although investigated ILs affected root and shoot growth of cucumber, the effect on stress marker (MDA) as well as biosynthesis of chlorophyll and carotenoids was negligible. The data collected in this research suggest that tuning of the lipophilicity of imidazolium cations by the introduction of polar groups in the side alkyl chain does not have pronounced effect on cucumber, as it was shown for other plant species.

Germination responses of Ballota hirsuta seeds under conditions of temperature, salinity and water stress

Summary Temperature, salinity and water deficit can be major environmental constraints which reduce distribution of indigenous plants in the Mediterranean region. Laboratory experiments were carried out to assess the effect of temperature, sodium chloride (NaCl) and polyethylene glycol 6000 (PEG) on germination of Ballota hirsuta seeds. The germination responses of seeds were determined over a wide range of temperature (5 to 35°C), salinity (0 to 136 mM NaCl) and water stress (0 to −1 MPa PEG). Germination percentage was optimum at 20°C (78%), and showed a decline at lower (5°C, 25%) or higher (30°C, 18%) temperature values and total inhibition of germination at 35°C. Under salinity and water stress conditions, there was a significant deterioration in most germination parameters such as lower final germination percentage, increased mean germination times and lower germination rates.

Phytotoxic effect of Haldina cordifolia on germination, seedling growth and root cell viability of weeds and crop plants

The extracts of wood, bark, and leaves of Haldina cordifolia were evaluated for their phytotoxicity on seed germination, seedling growth, and root cell viability in two weeds (Mimosa pigra and Cenchrus echinatus) and two crop plants (Vigna radiata and Oryza sativa cv. Khao Dawk Mali 105). Seeds were grown in petri dishes and treated with 5ml of extracts at various concentrations: 0.5, 1.0, 5.0, and 10.0mg/ml. The inhibitory effect on seed germination increased with increasing concentration of the extract treatment. Bark extract was the most toxic at the highest concentration, causing total inhibition of germination in all tested seeds except in V. radiata. Low concentrations (0.5 and 1.0mg/ml) of wood extract inhibited shoot and root growth in C. echinatus by 31.0%–56.0% and 67.0%–71.0%, respectively. Interestingly, it promoted root growth in M. pigra by 106.9%–108.8% (at low concentrations) and in V. radiata (at all concentrations) by 108.1%–108.9% (shoot) and 108.8%–120.1% (root). Bark extract inhibited seedling growth in all tested plants at different levels. Strong inhibition was found in roots of O. sativa (3.0%–4.0%). The result from Evans blue uptake study suggested that the H. cordifolia extract did not directly affect the root cell viability. Surprisingly, we found that M. pigra and V. radiata treated with the extracts at low concentrations had increasing number of lateral roots, suggesting that H. cordifolia extract could act as a plant growth regulator (PGR) and an herbicide at the same time, depending on concentration and target plant.

In vitro inhibitory effects of rosemary and sage extracts on mycelial growth and sclerotial formation and germination of Sclerotinia sclerotiorum

The anti-fungal efficacy for two Labiate plants, rosemary (Rosmarinus officinalis L.) and Greek sage (Salvia fructicosa Mill.), against Sclerotinia sclerotiorum fungus (Lib.) de Bary has been investigated. The inhibitory effect of these plants as crude leaf ethanolic extract on the radial mycelial growth as well as on sclerotial production and germination was measured in vitro at various concentrations (stock = 0.5 g dry leaf powder/ml ddH2O) in the growth medium. In general, rosemary extract revealed a remarkable anti-fungal effect against the fungus, being more inhibitory than Greek sage in this respect. This was evident as total inhibition of radial mycelial growth by rosemary occurred at 10% extract concentration, while sage was half as potent producing such an effect at double the concentration (20%). Both rosemary and sage extracts were more inhibitory to sclerotial formation than to mycelial growth as the fungus ceased to produce any sclerotia at the lower concentrations of 5 and 5–10%, respectively. In addition, rosemary was highly effective in inhibiting sclerotia germination as total inhibition of germination occurred at 20% extract concentration at three days and onward after incubation. Moreover, at this level, the survival of sclerotia was totally lost when examined after 12 days of incubation. For sage, inhibition of sclerotial germination/death was only 20% at 12th day of incubation. The results of this study indicate that the extracts of rosemary and Greek sage leaves could become natural alternatives to synthetic fungicides to manage diseases of S. sclerotiorum.

Chromotoxic effects of exogenous hydrogen peroxide (H2O2) in barley seeds exposed to salt stress

The effect of exogenous hydrogen peroxide (H2O2) on mitotic activity and chromosomal aberrations in root tip meristems of barley (Hordeum vulgare L. var. Tokak 157/37) germinated under salinity was analyzed. The inhibitory effect of salinity on mitotic index and the frequency of chromosomal aberrations increased with increasing salt concentration (0.00 control, 0.35, 0.40, 0.45 M, molal NaCl). The frequency of chromosomal aberrations of seeds germinated in medium with 0.40 M NaCl after pretreatment with H2O2 (30 μM, micromolal) was significantly higher than the control group. The highest concentration of NaCl (0.45 M) together with H2O2 caused total inhibition of germination. In this study, the intention was to determine the performance of H2O2 in alleviating detrimental effect of salt stress on mitotic activity and chromosomal aberrations. However, H2O2 did not reduce the detrimental effect of NaCl on these parameters. Also, it caused higher chromotoxic effect compared to those of control groups.

Germinação de sementes de Erythrina speciosa Andr., Eugenia brasiliensis Lam. e Cucumis sativus L. em meio ácido

Muitos estudos situam a germinação das sementes dentre os estágios de desenvolvimento extremamente vulneráveis às condições ambientais e que a resposta germinativa à acidez pode auxiliar o conhecimento sobre diferenças na composição florística. Sementes de duas espécies nativas (Erythrina speciosa Andr. e Eugenia brasiliensis Lam.) e uma cultivada (Cucumis sativus L.) foram avaliadas quanto à germinação em diferentes níveis de acidez e a concentrações de alumínio, esta relacionada indiretamente com o pH do solo. Sementes de E. speciosa e C. sativus germinaram inclusive em pH 1,0. O alumínio afetou a germinação das três espécies, com inibição em pH 1,0 e 2,0. Constatou-se que as sementes de E. brasiliensis apresentaram a maior suceptibilidade às condições químicas do meio. Os resultados demonstraram que o efeito da acidez sobre a germinação provavelmente ocorre entre a fase de embebição e a fase da protrusão da radícula.

Efeito da temperatura sobre a germinação de três espécies de Pinus cultivadas no Brasil

As espécies de Pinus apresentam alto nível de resistência aos incêndios florestais, razão por que são consideradas, por alguns, plantas pirófitas ativas. Daí se perguntar: o comportamento das sementes dessas espécies evoluiu exclusivamente em relação às perturbações produzidas pelo fogo, ou por outras causas que tenham influenciado esse processo, e, ainda, essas espécies desenvolveram respostas adaptativas similares? Para responder a essas perguntas, submeteram-se sementes de três espécies de Pinus a várias temperaturas e tempo de exposição, para simular resposta aos diferentes regimes de calor, avaliando efeitos provocados na germinação das sementes pelas elevadas temperaturas e o efeito das cinzas, tido como elemento mais notável do micro-ambiente em que se desenvolverão, posteriormente, os propágulos. O material vegetal empregado foi adquirido do Instituto de Pesquisas e Estudos Florestais (IPEF) em Piracicaba, SP. Para avaliar a resposta das sementes ao efeito das temperaturas, usou-se um delineamento estatístico inteiramente casualizado com arranjo fatorial. Na ausência de tratamentos térmicos, as sementes apresentaram altas taxas de germinação e forte redução a partir de temperaturas iguais ou superiores a 70 ºC, indicando que, realmente, não são plantas pirófitas ativas. Os valores da germinação obtidos com os tratamentos de temperatura igual a 50 ºC diferiram estatisticamente dos da testemunha, e, quando os valores da temperatura foram iguais ou superiores a 110 ºC, observou-se importante redução da germinação em todos os tratamentos. A avaliação simultânea do calor e das cinzas evidenciou que existe interação entre os fatores, com inibição total da germinação em alguns tratamentos.

The reversible inhibition of pollen germination of Nicotiana tabacum L.: an entry into a transformation system

The hydrodynamics of mature pollen rehydration in Nicotiana tabacum was used to study reversible inhibition of pollen germination in vitro. Tobacco pollen was incubated for various times in media containing calcium, potassium and magnesium salts, boric acid, and exhibiting different osmotic pressures as a function of sucrose concentration. Total inhibition of germination with complete viability preservation was achieved for 56 h by keeping the grains in medium with 80% sucrose, since typical percentages of germination and pollen tube lengths were recovered after this treatment. These effects were considered as consequences of natural osmoregulation of rehydration/germination in mature pollen. The possibility of applying these findings to the incubation of pollen with Agrobacterium tumefaciens to develop a pollen transformation method is discussed.

The progamic phase in Cichorium intybus L. Pollen tube growth in the style, incompatibility reaction and gametophytic competition

Pollen germination and tube growth were studied following compatible, incompatible and pseudo-compatible pollinations in chicory. Pollen germination begins 3 minutes after compatible pollinations. The earliest pollen tubes reach the ovary 17 minutes later. Many of the later germinating pollen tubes are arrested and burst at the stigma papillae. In the transmitting tissue inhibitional effects due to negative interactions between pollen tubes are frequently observed. Complete self-incompatibility results in total inhibition of germination. In case of pseudo-self-compatibility, some pollen germinate but germination and stigma penetration are delayed and often result in pollen bursting. There is no self-incompatibility reaction in the transmitting tract but if the pollen tubes reaching this tissue are relatively numerous, negative interactions between them occur as after compatible pollinations. An hypothesis is presented which attributes the negative interactions between pollen tubes to the diffusion of a substance from the growing pollen tubes. This substance would also provoke pollen bursting on the stigma.

Germination of Bacillus cereus Spores: Critical Control by DL-Alanine Racemase

Effects of dl-alanine racemase, D-alanine, heat-activation and ammonia on germination of Bacillus cereus T spores were studied. Michaelis-Menten parameters for dl-alanine racemase activity in intact spores were: K m (l-alanine)=3·6 mm; K m (d-alanine) = 1·2 mm; V max (l- to d-alanine) = 1·6 μmol min−1 (mg dry spores)−1; V max (d- to l-alanine) = 0·53 μmol min−1 (mg dry spores)−1. Racemase activity was irreversibly inhibited with pseudo first order kinetics by incubating intact spores with 10 mm-d-cycloserine. (Aminooxy)acetate (50 μm) completely inhibited racemase activity with 100 mm-l-alanine as substrate. d-Cysteine was a moderately effective racemase inhibitor. Comparisons of the effects of racemase inhibitors, d-alanine and spore concentration on germination rates in 1 mm-l-alanine indicated that racemization of l-alanine accounted for nearly total inhibition of germination at spore concentrations exceeding about 50 μg ml−1, in the range conventionally used for spectrophotometric germination assays. Heat-activation decreased the inhibitory effect of d-alanine, increasing the germination rate in 2 mm-racemic alanine by a factor of 26. Using spores with an inhibited alanine racemase, germination rates in 1 mm-l-alanine were stimulated by 40 mm-NH4Cl to an extent comparable to the stimulation obtained by heat-activating the spores. Germination of unactivated spores in 1 mm-l-alanine + 40 mm-NH4Cl was completely inhibited by 1 mm-d-alanine. These results clarified the roles of d-alanine and dl-alanine racemase in controlling the germination of unactivated spores and suggested that the germinative functions of ammonia and the stereoisomers of alanine may be related.

Pollen Germination and Tube Elongation in Petunia Inhibited or Reduced by Commercial Formulations of Pesticides in Vitro

Thirty-two commercial formulations of pesticides (insecticides, acaricides, and fungicides) were tested for their effect on the germination and tube elongation of petunia pollen on an artificial medium. The degree of inhibition of germination caused by 1000 ppm of actual material of the formulations ranged from total to no inhibition. The spray adjuvant DuPont Spreader Sticker at 1000 ppm caused total inhibition of germination and accentuated markedly the toxicity of those pesticides with which it was combined. Xylene at 1000 ppm was not injurious to pollen. The strong inhibiting effect of naled on pollen germination was slightly mitigated by rinsing the treated pollen with a calcium chloride-boric acid solution.