Radicle Growth Of Lettuce Research Articles

Evaluation of Allelopathic Activity Interactions of Some Medicinal Plants Using Fractional Inhibitory Concentration and Isobologram

Allelopathy is a physiological process with an ecological concept and application. Allelopathy is the result of the production of biologically active molecules by growing plants or their remains, which may have a direct effect on the growth and development of individuals of the same species or other species after changing their shape and entering the environment. As regards, the use of natural compounds in the control of weeds and pests is a priority. In this research, the allelopathic activity of 123 specimens of medicinal and aromatic plants were investigated individually by the dish-pack method using lettuce seeds as a model. Then, the strongest inhibitory ones were selected and their allelopathic interaction effects were investigated for the first time by interacting them together. Two methods were used to evaluate allelopathic interaction effects: calculating Fractional Inhibitory Concentration (FIC) and drawing Isobologram diagrams. Lettuce hypocotyl length, root length, germination percentage, and germination rate were investigated. Pelargonium graveolens (leaf) had the greatest inhibitory effect on lettuce radicle growth (EC50 = 5.31 mg/well) and Echinophora platyloba (stem) had the greatest effect on hypocotyl growth inhibition (EC50 = 7.91 mg/well). Also, the lowest lettuce germination percentages were observed in the treatments Lavandula officinalis (flower) and Nepeta binaloudensis (leaf), respectively (23.61, 22.85%). The highest inhibitory effect by considering lettuce germination rate was detected in Salvia ceratophylla (leaf), (12.86 seed/day) and the lowest belonged to Nepeta binaloudensis (leaf) and Lavandula officinalis (flower), respectively (3.60, 3.32 seed/day). According to FIC calculations and isobolograms, two types of interaction, including synergist (Nepeta binaloudensis (leaf) with Trachyspermum ammi (fruit) and Nepeta binaloudensis (leaf) with Lavandula officinalis (flower) and antagonist (Pelargonium graveolens (leaf) with Lavandula officinalis (flower)), were observed significantly among the plants tested in this research. These interactions can be used to prepare more effective natural herbicides and decrease the use of herbicides.

Determination of the Allelopathic Potential of Cambodia’s Medicinal Plants Using the Dish Pack Method

Plants produce several chemically diverse bioactive substances that may influence the growth and development of other organisms when released into the environment in a phenomenon called allelopathy. Several of these allelopathic species also have reported medicinal properties. In this study, the potential allelopathic effects of more than a hundred medicinal plants from Cambodia were tested using the dish pack method. The dish pack bioassay method specifically targets volatile allelochemicals. Twenty-five species were found to have significant inhibitory effects on lettuce radicle growth. Eleven different plant families, including Iridaceae (2), Apocynaceae (2), Poaceae (2), Sapindaceae, Araceae, Combretaceae, Orchidaceae, Clusiaceae, Zingiberaceae, Rutaceae and Asparagaceae had the plant species with high inhibitory effects. Allophyllus serrulatus had the highest growth inhibitory effect on lettuce radicles more than 60%, followed by Alocasia macrorrhiza, Iris pallida, Terminalia triptera, Wrightia tomentosa, Cymbidium aloifolium, Garcinia villersiana and Kaempferia parviflora. The candidate species were subjected to further studies to identify the volatile allelochemicals in the volatile constituents.

Plant Growth Inhibitory Activities and Volatile Active Compounds of 53 Spices and Herbs.

The inhibitory activities of the leachates and volatiles from 53 plant species (spices and herbs) were evaluated against lettuce (Lactuca sativa “Great Lakes 366”) seedling growth using the sandwich and dish pack methods, respectively. With the sandwich method, parsley (Petroselinum sativum) showed the strongest inhibitory effect on lettuce radicle growth (77%), followed by tarragon (Artemisia dracunculus) (72%). However, caraway (Carum carvi), dill (Anethum graveolens) (seed), laurel (Laurus nobilis), rosemary (Rosmarinus officinalis), and sage (Salvia officinalis) were the most inhibitory species (100% inhibition of lettuce radicle and hypocotyl growth inhibition at all distance wells) in the dish pack method. Cardamom (Elettaria cardamomum) and thyme (Thymus vulgaris) also showed strong inhibitory activity (100% for radicle and hypocotyl growth inhibition at all 41 and 58 mm distance wells). The headspace sampling and gas chromatography-mass spectrometry (GC-MS) analysis identified the main inhibitory active compounds as carvone in caraway and dill (seeds), 1,8-cineole in laurel and cardamom, and borneol in thyme. Both camphor and 1,8-cineole were detected in rosemary and sage, and the total activity evaluation showed that camphor was the major inhibitory compound in rosemary, although both compounds played equal roles in sage.

Application of the protoplast co-culture method for evaluation of allelopathic activities of volatile compounds, safranal and tulipalin A

The effects of two plant volatile compounds (VOCs), safranal and tulipalin A were investigated using the protoplast method with digital image analysis, which was developed to investigate allelopathic activities of plants at the cellular level in a 50 μL liquid medium. Both VOCs showed inhibition on lettuce protoplasts growth at all three stages, i.e., the cell wall formation stage, the cell division stage, and the yellow colour accumulation stage. Among the three stages of protoplast growth, differences of inhibition patterns were observed. Inhibitions at the cell wall formation stage were stronger than those at the latter two stages in both VOCs. Tulipalin A showed higher inhibitory activity (total inhibition at 100 μM) than that of safranal (44% inhibition at 1 mM) at cell division stage. They were also compared with the direct exposure method in an enclosed vial using germinated lettuce seedlings, which was developed to investigate allelopathic activities of VOCs at plant level. Tulipalin A showed less inhibitory activity on radicle growth of lettuce, than that of safranal reported. Inhibition on hypocotyl growth was stronger than that on radicle in both VOCs. The causes of the differences between two VOCs and two bioassay methods, and the application of the protoplast method, were discussed for clarifying the contribution of VOCs as allelochemicals at cellular level.

A study of the phytotoxic effects of the aerial parts of Senecio westermanii Dusén (Asteraceae) on Lactuca sativa L. and Allium cepa L. seeds

The objective of this study was to evaluate the effects of the ethanolic crude extracts and fractions of the species Senecio westermanii Dusen on Lactuca sativa L. (lettuce) and Allium cepa L. (onion) seeds. We assessed the germination, growth, root respiration and photosynthesis of the target species in Petri dishes (9.0 cm diameter) containing filter paper n°6. The study was conducted using 50 seeds per plate and held in 4 replicates per concentration of each sample. In the germination there was an inhibitory effect of fractions hexane (FH) and chloroform (FCl) at concentrations of 500 and 1000 µg/mL. There was a reduction in the radicle growth of lettuce by 14 to 24% and a reduction of hypocotilum by 14 to 28%. As for the radicle of the onion was up 74% reduction to the FCl and the coleoptile was 24 and 45% reduction for FH and FCl, respectively. Inhibitory effects in the root respiration of lettuce were detected in all the samples analyzed, with results ranging from 16 to 83%. For the seeds of A. cepa, there was an encouragement for the FCl and ethyl acetate fractions (FAE), with results ranging from 94 to 142% and 76 to 150%, respectively. With regard to the photosynthesis of L. sativa, there was no significant difference between the control, and as for the A. cepa, there was a strain in inhibition concentrations of 250 and 500 µg/mL, which ranged from 27 to 68%. The samples of S. westermanii caused changes in the target species and thus can be used as a natural herbicide.

LC-MS characterization and reduction of the phytotoxic effect of aluminium by natural products from Eugenia jambolana Lam.

The objective of this study was to quantify the flavonoids present in the Eugenia jambolana Lam extract and fractions, identify their composition by LC-MS, to determine the cytoprotective potential against aluminium Chloride toxicity in a prokaryotic and eukaryotic model, as well as the mechanism of cytoprotection of the extract and fractions. The ethanolic extract from E. jambolana, as well as its tannic and flavonoid fractions, were tested and the minimum bactericidal and fungicidal concentration of the products associated with aluminum chloride in different concentrations were established. These same products were used in the germination of lettuce seeds (Lactuva sativa). The extract and fractions did not show cytoprotective activity in bacterial and fungal models, since it was not able to interfere with the growth profile of these microorganisms. In relation to the vegetal model, it was possible to observe significant effects on caulis and lettuce radicle growth, as well as on the dry weight of radicles, showing a cytoprotective effect capable of inhibiting the aluminum chloride toxicity at different concentrations. In this way, due to the problems faced with aluminum contamination and the characteristics of the soils the E. jambolana extract may show an alternative to the toxicity of this metal.

Evaluation of the Allelopathic Potential of Fifteen Common Malaysian Weeds

The use of allelopathy concept in weed management has received attentions to minimize extensively the reliance on herbicide applications on the agriculture industry in Malaysia. A laboratory study was conducted to evaluate the allelopathic potential of 15 Malaysian common weed species of different morphological characteristics (broadleaves, sedges and grasses). They were screened using the Sandwich method (from leaf litter leachate) and the Dish pack method (for testing the presence and content of volatile compounds in weeds). Among the 15 weed species tested, the leaf litter leachate of Centrosema pubescens was observed to be the most sensitive plant material inhibiting the growth of lettuce radicle (84%) and hypocotyl (55%) in the Sandwich bioassay compared to the control. This was followed by Asystasia gangentica (81%) and Cynodon dactylon (80%) inhibiting the lettuce radicle growth. In the Dish pack bioassay, Rhynchelytrum repens demonstrated maximum inhibition on the radicle and hypocotyl elongations by 44% and 29%, respectively, (over control) at 41 mm distance from the source well. Meanwhile, at the same distance, Cynodon dactylon was observed to have the least inhibitory effect on lettuce radicle growth by 12%. The results presented can be utilized as benchmark information for further research on the identification and isolation of allelochemicals for weed control strategies.

Exploring Alternative Use of Medicinal Plants for Sustainable Weed Management

This paper presents the first application of ethnobotanical studies to screen for allelopathic species among medicinal plants for sustainable weed management. This study assesses the possible relationship between ethnobotanical indices and allelopathy of medicinal plants. Ethnobotanical data were collected in 2016 by using semi-structured interviews with 140 informants in the Ejisu-Juaben Municipality, Ghana. Data were analysed using statistical tool and ethnobotanical indices including use value (UV), Fidelity Level (FL), Relative Frequency of Citation (RFC). The Sandwich and Dish pack methods were respectively used to evaluate allelopathy through leachates and volatiles of collected samples. Ninety-five species belonging to 43 families are reported in this study, with leaves (52%) cited the most utilised plant part. Cleistopholis patens (UV = 0.54; FL = 90.7%; RFC = 0.37) and Ocimum gratissimum (UV = 0.37; FL = 38.4%; RFC = 0.35) were among the most cited species. Thirty-two species showed inhibition (≥49.3%) by leachates, while twenty-four species were found with potential volatile inhibitory compounds against lettuce radicle growth. There was a significant positive correlation (Pearson) between the UV and RFC of medicinal plants and allelopathy by leaf leachates (r = 0.639 **; p = 0.01 and r = 0.653 **; p = 0.01 respectively). This systematic documentation of medicinal plants in Ejisu-Juaben Municipality shows medicinal plants with ethnomedicinal values and potential allelopathy that can be utilised in sustainable weed control.

Determination of allelopathic potentials in plant species in Sino-Japanese floristic region by sandwich method and dish pack method

<p>The Sino-Japanese Floristic Region appears as one of the major centers of development of higher plants. This region have been relevant for the study of evolution and systematics of many flowering plants. The taxonomic richness of endemic plant species in this region have survived several years of extreme climate conditions. Endemic mountainous plant species that have survived extreme climate conditions are of allelopathic and medicinal interest. For this reason, 251 plant species collected from the Sino-Japanese Floristic Region were screened for allelopathic plant species. Sandwich method and dish pack method were respectively used to screen plant leaf leachates and volatile materials with lettuce (<em>Lactuca sativa</em> CV. Great Lakes 366) as receptor plant. Among the 84 species that showed inhibitory effect on lettuce radicle elongation in our sandwich bioassay, <em>Photinia glabra </em>showed complete inhibition of lettuce radicle elongation (0% radicle elongation). In the dish pack bioassay, <em>Photinia glabra</em>, <em>Liquidambar styraciflua</em>, and <em>Cinnamomum camphora</em> (90.6%, 61.4%, and 50.2% respectively) were among the nine species that were observed with strong inhibitory effect on lettuce radicle growth. On the other hand, nine other species promoted lettuce radicle growth when compared to the control. <em>Aesculus turbinata</em> and <em>Quercus gilva</em> were the species with the highest growth stimulatory effect (33.0% and 16.1% respectively). We hereby present <em>Photinia glabra </em>as an allelopathic candidate species for both leachate and volatile compounds.</p>

Natural Products from Polygonum perfoliatum and their Diverse Biological Activities

Nine components were isolated from the methanol extract of the whole herb of Polygonum perfoliatum and evaluated for their antioxidant activity. Among them, α-tocopherol and methyl trans-ferulate showed significant DPPH free radical scavenging effects with EC50 values of 11.9 and 7.8 μg/mL, respectively. In addition, five phenolic acids, caffeic acid, p-coumaric acid, p-hydroxybenzoic acid, protocatechuic acid, and vanillic acid were isolated from the aqueous extracts of the plant and identified by means of paper and high performance liquid chromatography. These five compounds were confirmed to be allelopathic substances by bioassay against the radicle growth of lettuce ( Lactuca sativa), Chinese cabbage ( Brassica oleracea), and radish ( Raphanus acanthiformis).

Regulation effect of Phyllostachys pubescens methanol extractives on growth of seed plants

Methanol extractives from moso bamboo (Phyllostachys pubescens) culms were found to have some regulation effects on the growth of the seed plants tested. They showed inhibition or promotion of hypocotyl and radicle growth of lettuce, watercress, and chrysanthemum. The methanol extractives were fractionated with n-hexane, diethyl ether, and ethyl acetate. The diethyl ether-soluble fraction contained more phenolic substances than the other fractions and showed strong inhibition of growth in lettuce seeds. The water-soluble fraction showed a promotion effect on the hypocotyl growth of lettuce. The water-soluble fraction was heated at 200°C for 8h, and the inhibition effect on the radicle growth of lettuce decreased and the promotion effect on the hypocotyl growth increased at 0.1% concentration.

L-3-(3,4-Dihydroxyphenyl)alanine (L-DOPA), an allelochemical exuded from velvetbean (Mucuna pruriens) roots

We investigated whether or not lettuce growth was inhibited by diffused L-3-(3,4-dihydroxyphenyl)alanine (L-DOPA), an allelochemical exuded from the roots of velvetbean (Mucuna pruriens (L.) DC. var. utilis) cultivars using a modified plant-box bioassay. For all the cultivars and one accession examined L-DOPA diffused from the roots and caused radicle and hypocotyl growth inhibition. A high correlation co-efficient (r = 0.838 to 0.982) was observed between L-DOPA concentration and lettuce seed sowing distance. L-DOPA diffused equally in all directions from roots at 0 mm position (close to root surface) in the plant-box, while the inhibition (%) of lettuce radicle growth gradually decreased with distance from the roots. For all cultivars the concentration of L-DOPA was significantly different at 0 mm position: being highest in cv. preta (167 μg/ml) and lowest in cv. jaspeada and cv. ana (13 μg/ml). The correlation between lettuce radicle growth inhibition and concentration of diffused L-DOPA was high (r = 0.856 to 0.966) in all cultivars and accession examined. However, the concentration of diffused L-DOPA did not correlate with the fresh weight concentration of L-DOPA measured in roots. The lettuce radicle growth inhibition from mucuna diffused L-DOPA was very similar that induced by synthetic L-DOPA, suggesting that diffused L-DOPA was the allelochemical responsible for growth inhibition.

Induction of Ageotropic Response in Lettuce Radicle Growth by Epicuticular Flavonoid Aglycons of Dittrichia viscosa

Thirteen flavonoid aglycons, contained in the strongly allelopathic epicuticular exudates of Dittrichia viscosa, were investigated for their effects on lettuce seedling radicle growth. Concerning radicle length and mass, variable results were obtained, with most of the substances having no effect, some being inhibitory and some even promotive. Shoot mass was slightly reduced in four cases. Seed germination rates, root hair and lateral root formation were not affected either. Three of the compounds (namely quercetin 3,3-dimethylether, naringenin and eriodictyol) induced a strong ageotropic response in radicle growth.

A growth-inhibitory substance exuded from freeze-dried mesquite (Prosopis juliflora (Sw.) DC.) leaves

When lettuce seeds were incubated in a concentric circle aroundfreeze-dried mesquite leaves in a dish containing agar culture medium, thegrowth, especially radicle growth, of the seedlings was inhibited, the morestrongly the closer they were to the leaves. This result indicates thatallelopathic substance(s) inhibiting the lettuce growth are exuded from themesquite leaves. A potent substance was isolated from the exudates of thefreeze-dried mesquite leaves and identified as L-tryptophan by spectralanalyses. L-Tryptophan inhibited the radicle growth of lettuce and barnyardgrass at concentrations greater than1.5 × 10−3 . The content ofL-tryptophan in the exudates of freeze-dried mesquite leaves (1 eq.) was 4.8 × 10−3 . Theseresults suggest that L-tryptophan may play an important role in the allelopathyof mesquite leaves.

Allelopathic potential ofnuphar lutea (L.) Sibth. & Sm. (Nymphaeaceae)

Aqueous extracts ofNuphar lutea (L.) Sibth. & Sm. leaves (blades plus petioles) and roots plus rhizomes were tested for allelopathic activity using lettuce seedling andLemna minor L. assay systems. The 12.5, 25, 125, and 250 parts per thousand (ppt) treatments of both extracts killed the lettuce seedlings. At 2.5 ppt of extract, radicle growth of lettuce was 29% of the control for leaves and 31% of the control for roots plus rhizomes.Lemna minor frond number was reduced to 34% of the control by the 25 ppt leaf extract and to 43% of the control by the 25 ppt roots plus rhizomes extract.L. minor was killed by concentrations of 125 ppt and above of both plant part extracts. As expected, the frond number and total chlorophyll content measured by theL. minor assay were highly correlated. Osmotic potentials below 143 mOsmol/kg had no influence onL. minor growth. Neither the osmotic potential nor the pH of the undiluted extracts ofN. lutea were in the range known to influence the growth of either lettuce seedlings orL. minor. Nuphar lutea extracts were many times more inhibitory than 16 other hydrophytes we previously examined.

Allelopathic actions in the Florida scrub community

The hypothesis that allelochemicals released from members of the Florida scrub community deter the invasion of fire-prone sandhill grasses was investigated. Constituents of the endemic scrub members, Ceratiola ericoides, Conradina canescens and Calamintha ashei, were examined for their phytotoxic activity. Effects of the plant natural products on the germination and radicle growth of lettuce (Lactuca sativa), as well as little bluestem (Schizachyrium scoparium) and green sprangletop (Leptochloa dubia), two native grasses of the Florida sandhill community, were tested.The data suggest that ursolic acid and other natural detergents which are released from a source plant enhance the solubilization of allelopathic lipids via micellization. In general, natural surfactants seem to play a significant role in the water transport of lipophilic phytotoxins to target seeds or seedlings.

Allelopathic research of subtropical vegetation in Taiwan

Leucaena leucocephala plantations in Kaoshu, southern Taiwan, exhibit, after several years of growth, a unique pattern of weed exclusion beneathLeucaena canopy. The pattern has been observed in manyLeucaena plantations in Taiwan and is particularly pronounced in the area where a substantial amount ofLeucaena litter has accumulated on the ground. Field data showed that the phenomenon was primarily not due to physical competition involving light, soil moisture, pH, and nutrients. Instead, aqueous extracts ofLeucaena fresh leaves, litter, soil, and seed exudate showed significantly phytotoxic effects on many test species, including rice, lettuce,Acacia confusa, Alnus formosana, Casuarina glauca, Liquidambar formosana, andMimosa pudica. However, the extracts were not toxic to the growth ofLeucaena seedlings. The decomposing leaves ofLeucaena also suppressed the growth of the aforementioned plants grown in pots but did not inhibit that ofLeucaena plants. By means of paper and thin-layer chromatography, UV-visible spectrophotometry, and high-performance liquid chromatography, 10 phytotoxins were identified. They included mimosine, quercetin, and gallic, protocatechuic,p-hydroxybenzoic,p-hydroxyphenylacetic, vanillic, ferulic, caffeic, andp-coumaric acids. The mature leaves ofLeucaena possess about 5% dry weight of mimosine, the amount varying with varieties. The seed germination and radicle growth of lettuce, rice, and rye grass were significantly inhibited by aqueous mimosine solution at a concentration of 20 ppm, while that of the forest species mentioned was suppressed by the mimosine solution at 50 ppm or above. However, the growth ofMiscanthus floridulus andPinus taiwanensis was not suppressed by the mimosine solution at 200 ppm. The seedlings ofAgeratum conzoides died in mimosine solution at 50 ppm within seven days and wilted at 300 ppm within three days. It was concluded that the exclusion of understory plants was evidently due to the allelopathic effect of compounds produced byLeucaena. The allelopathic pattern was clearly shown in the area with a heavy accumulation ofLeucaena leaf litter, which was a result of drought and heavy wind influence.

Allelopathic research of subtropical vegetation in Taiwan II. Comparative exclusion of understory byPhyllostachys edulis andCryptomeria japonica

On many hillsides of Taiwan there is a unique pattern of weed exclusion byPhyllostachys edulis (bamboo) andCryptomeria japonica (conifer) in which the density, diversity, and dominance of understory species are very different. Although the physical conditions of light, soil moisture, and soil nutrients strongly favor the growth of understory in a bamboo community, the biomass of its undergrowth is significantly low, indicating that physical competition among the understory species in the bamboo and conifer communities does not cause the observed differences. However, the biochemical inhibition revealed by these two plants appeared to be an important factor. The growth ofPellionia scabra seedlings, transplanted from the study site into greenhouse pots, was evidently suppressed by the aqueous leachate of bamboo leaves but was stimulated by that of conifer leaves. The radicle growth of lettuce, rye grass, and rice plants was also clearly inhibited by the leachate and aqueous extracts of bamboo leaves but not by those of conifer leaves. Six phytotoxins,o-hydroxyphenylacetic,p-hydroxybenzoic,p-coumaric, vanillic, ferulic, and syringic acids were found in the aqueous leachate and extracts of leaves and alcoholic soil extracts ofP. edulis, while the first three compounds were absent in the extracts ofC. japonica. The phytotoxicities of extracts were correlated with the phytotoxins present in both leaves and soils. The understory species might be variously tolerant to the allelopathic compounds produced by the two plants, resulting in a differential selection of species underneath. Therefore, comparative allelopathic effects ofPhyllostachys edulis andCryptomeria japonica may play significant roles in regulating the populations of the understories.

Autointoxication mechanism ofOryza sativa I. Phytotoxic effects of decomposing rice residues in soil

The aqueous extracts of decomposing rice residues in soil exhibited inhibition on the radicle growth of lettuce and rice seeds and the growth of rice seedlings. The phytotoxicity was found in extracts obtained from the early stage of decomposition (first month), and gradually declined thereafter. The inhibition was also found in extracts obtained from rice fields, and was persistent for 4 months. The root initiation of hypocotyl cuttings of mungbeans was suppressed by extracts of decaying rice residues and extracts obtained from paddy soil. Five phytotoxins,p-hydroxybenzoic,p-coumaric, vanillic, ferulic, ando-hydroxyphenylacetic acids, and several unknowns were found in the decomposing rice residues under waterlogged conditions. At 25 ppm,o-hydroxyphenylacetic acid revealed significant inhibition on the radicle growth of rice and lettuce seeds and suppressed root initiation of mungbean seedlings. It was concluded that the growth of rice seedlings was retarded by decaying rice residues in soil; thus, this appeared to be an autointoxication phenomenon.