جستجوی مقالات مرتبط با کلیدواژه "آللوپاتی" در نشریات گروه "گیاهپزشکی"

The use of allelopathic materials has been a favorite natural herbicide for plant scientists. The effect of these natural compounds is more than artificial compoundsdue to its water-soluble and halogen-free characteristics. Regarding the increasing resistance of weeds to herbicides, application ofallelopathic method can reduce the use of artificial herbicides and prevent environmental degradation. The purpose of this study was investigation of using Euphorbia heterophylla metabolites in growth and germination control of weed Avena Ludoviciana in farms In order to investigate the allelopathy effects of aqueous and alcohol extracts of (heterophylla Euphorbia), an experiment was conducted at Agricultural Research Center of Golestan (Gorgan city) Province during 2014 and 2015 with a completely randomized design under greenhouse condition on Avena ludoviciana with three replications. The treatments in this experiments were the plant species organs at 2 levels (dry powdered of leaf and stem), solvent type for preparing extracts at 2 levels (water and alcohol(methanol)) and the extract concentrations at 5 levels (0, 25, 50, 75 and 100 percentage).The measured traits included height, leaf wet weight, leaf dry weight, stem wet weight, stem dry weight and leaf area. The aqueous and alcoholic extract of Euphorbiaheterophylla were obtained by dipping of dried material in the special solvents in dark place at room temprature for three days and finally, filtration with muslin cloths. The prepared extracts was stored in 4 degree centigrad refrigerator. This extrat was considered as stock solution and the rest concentrations were preapared from this solution.The extracts sprayed on the target plant (Avenaludoviciana) as post-emergence at 3-4 leaved stages.Total phenolic content was measured using the Folin-Ciocalteu reagent method and the total flavonoid content of the extracts was surveyed by a colorometric method based on aluminum chloride.Finally, the relative recognition of the nature of plant compounds was done by chemical methods and colorimetry.The data were analyzed with SAS, 9.9 software and the means were compared to eache other using LSD (least significant difference) at (p < 0.05) and the graphes was drawn with Excel software. Based on the results of the analysis of variance, except for leaf area of Avena ludoviciana which was affected by the treatments at 95% confidence level (p < 0.05), all the measured traits were significantly affected by the treatments at 99% confidence level (p < 0.01). In general, the results of this study showed that the aqueous extracts of Euphorbia heterophylla stem and leaves had no inhibitory effects on the measured traits at zero levels (control treatment), but the growth and germination of Avena ludoviciana was inhibited by the leaf alcoholic extract and stem aqueous extract at 50 and 100% concentration. These extracts significantly decreased plant height, stem fresh weight, leaf fresh weight and leaf dry weight of Avena ludoviciana. The highest effect was observed on Avena ludoviciana leaf area at 100% concentration of leaf extract and the lowest effect was observed at 75% concentration of stem extract. The results of phytochemical experiments of the aqueous and alcoholic extract of the leaves indicated that the aqueous extract of leaves and stems followed by alcoholic extract of leaves had the highest phenolic compounds and also highest antioxidant properties, respectively. According to the results of this study, it is suggested that, further research must be carried out on the identification and mechanism of action of Euphorbia heterophylla allelopathic compound and their effects on Avena ludoviciana seedlings growth. Thus, it can be used as an alternative source of antioxidant compounds in the organic fertilizer industry. Based on the phytochemical experiments conducted in this study, the existence of secondary metabolites in the Euphorbiaheterophylla extracts was proved. The obtained results from the different extracts (aqueous extract of stem, aqueous extract of leaf, alcoholic extract of stem and alcoholic extract of leaf) showed thatthe alcoholic extracts of leaves significantly affected the growth traits of Avenaludovicianamore than the rest of extracts.It seems that attempting to accurately identify the chemical nature of the allelopathic compounds present in different organs of Euphorbiaheterophyllaand the factors that affecting these compounds can lead to the other studies based on biological weed management.

Widespread use of herbicides in agriculture has led to loss of natural habitats, increase in pollution, generating herbicide-resistant weeds, risk of food poisoning and lower food quality. So new approaches are required in management, production, and utilization of the existing agricultural practices for sustainable agriculture. There are several techniques in this regard including allelopathy. Use of allelopathic compounds is a new approach for lowering undesirable effects of herbicides on the environment and fighting weeds resistant to herbicides. Recently allelopathy knowledge has been developed because of innovative methods and collaboration among scientists and achievements in suitable bioassays. Nowadays, old methods such as petri dishes or activated charcoal method have been replaced by new methods such as dish pack, sandwich, rhizosphere, and plant box. Researchers have indicated that many problems might be solved in allelopathy studies through these methods. Sandwich method is considered as one of the alternative methods for the old ones and is a very useful tool for screening the allelopathic effect of leaf litter under laboratory conditions. This method is a less time-consuming bioassay method and could be applied to screen more samples. Besides, allelopathic properties of many plants are evaluated using fewer plant samples through this method.
In this study, using a sandwich method, allelopathic properties of 55 plant species (59 samples) from 27 families were studied. The majority of plants were collected in 2016 from the different regions of South Khorasan province, Iran. The samples authenticated. Then, different parts of plants used for laboratory studies at Agricultural Researches Institute in Birjand University, Iran. Lettuce (Lactuca sativa L. var Great Lake 366) was used as an index because of its seeds sensitivity in chemical compounds, and allelopathic properties on the growth of seedlings of these lettuce varieties were evaluated. To investigate the allelopathic activity, an experiment was conducted as a completely randomized design with 3 replications. In order to assess the allelopathic activity of the selected plants, multi-dishes were used with 6 holes. Each hole had 3.5 cm diameter (Nunc Company, Japan). Ten milligrams of dried samples were placed in all three wells in the upper row and fifty milligrams was placed in rest of three lower wells of the six-well multi-dish plate. For the preparation of the growth medium, commercially available agar was applied. The medium was prepared as 0.5 % (w/v) and autoclaved at 115 °C for 20 min. 5 mL of autoclaved agar was added to each well of the multi-dish plate containing plant samples. After gelatinizing the agar within 30–45 min at room temperature, 5 mL agar was added again to all wells as the second layer and left at room temperature for gelatinized again. This made a sandwich of dried leaves by two layers of agar. Five lettuce seeds were put on the agar surface of the wells and all treatments were replicated three times. Each side of the prepared multi-dishes was then sealed by parafilm and wrapped in aluminum foil to protect them from light penetration and then were placed in an incubator (25°C). After 3 days, length of radicle and hypocotyl were recorded and monitored compared to control samples. Agar medium without plant samples was used as the control.
Growth of radicle and hypocotyl of lettuce seedling was present in the form of either inhibition (positive value) or promotion (negative value). The results showed that among the studied plants, Mentha spicata, Nepeta cataria, and Nepeta glomerulosa herbs highly affected growth inhibitory on radicle (96.4 %) and hypocotyl (94.8 %) of lettuce seedlings. Moreover, leaves of Leptorhabdus parviflora and Allium oschanini seeds strongly showed allelopathic effects by inhibiting the growth of radicle (91.0 %) and hypocotyl (85.2 %) of lettuce. Viola tricolor flowers plant had allelopathic effect as a deterrent growth only on radicle growth (90.0 %) and did not have significant effects on hypocotyl. In the current research, the introductory screening was done on 55 plants to recognize the suspected plants containing allelopathic compounds. However, further research is needed on these plants to figure out their effects on weeds.
The plants introduced in this research are mainly contain compounds such as Carvone, Limonene, α-Pinen, β-Pinen, 1,8 cineol, Thymol, Anethol, Camphor, Nepetalactone, β-caryophyllene and Geraniol. The results suggested that introduced plants may fulfill the organic farming and production of naturally originated herbicides. Therefore, more attention is needed for the future research focusing on finding the allelopathic responsible compounds by GC-MS and NMR techniques for using in organic agriculture. It is also necessary to investigate the ability of herbivorous of these compounds specifically.

Excessive use of chemical herbicides has resulted to many problems such as adverse environmental impacts, contamination of groundwater and resistant weeds. Therefore, researchers are looking for solutions to reduce the use of herbicides as more as possible. One effective approach is to use the characteristics of allelopathic plants. To evaluate the allelopathic effects of extracts of madder on seed germination of several crops (corn and sorghum) and weeds (Johnsongrass and field bindweed), four separate laboratory experiments were conducted in 2011 at Yazd University of Applied Science. The experimental design was a completely randomized with 4 replications and 5 treatments. Treatments were madder extract at 5 levels (zero, 25%, 50%, 75% and 100%, respectively). The results showed that the extract of madder could decrease traits such as germination percentage and germination rate, root and shoot length, root to shoot ratio (R / S), seedling vigor index and total dry weight of all plants significantly (p

In order to identification of allelopathic compounds and investigation of the effect of aerial part extract of orchard grass on germination and seedling growth of alfalfa an experiment conducted as completely randomized design with four replications at University of Mohaghegh Ardabili, Iran. Treatments were concentrations of orchard grass extracts including 0, 25, 50, 75, and 100%. Radicle and plumule length, fresh weight of seedling, percentage and rate of germination were measured. Results showed that with increasing extract concentration there was a reduction trend in all studied traits (except of seedling fresh weight and plumule length which increased at lower concentrations and then declined). The highest content of allelopathic substances related to phenolic compounds (7.98 and 13.91 mg in root and shoot, respectively). Plumule length and seedling fresh weight increased at the concentrations between 23 to 26% and after then reduced sharply and prevented completely at 100% concentration. All the traits reached to zero at 100% concentration. Orchard grass allelopathic substances inhibited the germination and growth of alfalfa seeds at higher concentrations.

Weed chemical control has negative results on agroecosystems. Therefore، identification of cultivars tolerant to weeds has importance in nonchemical management. So، in this study، the tolerance of some alfalfa cultivars was studied to dodder. Anexperiment was conducted at research farm and laboratory of Shahed University in 2011. The farm experiment was done as split plot in time in randomized complete block design with three replicates. The treatments were included 12 alfalfa cultivars. The results showed that Local Hamedani and Fao were most sensitive and tolerant cultivars، respectively. Therefore، in laboratorial experiments، the effect of seed aqueous extract of Local Hamedani and Fao cultivars was evaluated on dodder seed germination. The experiment was conducted as factorial in randomized complete block design. The factors were seed extract of tolerant and susceptible cultivars of alfalfa at 5 levels، including zero (distilled water)، 25، 50، 75 and 100 percent concentration. The results indicated that the effect of different concentrations of the extract was not significant on dodder seed germination، but the effect of cultivar and interaction of cultivar and concentration were significant on dodder seed germination. Dodder seed germination decreased as Fao seed extract concentration increased while a reverse trend was seen in Local Hamedani cultivar. In general، it seemed that Local Hamedani cultivar has some substances in seed that could stimulate dodder germination however there was not seen such a result in Fao، the tolerant variety. Complementary experiments are decisive to attain accurate results.

In order to evaluate the allelopatic potential of wheat aquatic extracts against winter wild oat (Avena ludoviciana) at germiantion and vegetative growth stage two expriments were coducted in Islamic Azad University، Shoushtar branch at 2012. Germination expriment was laid out according to Completely Randomized Design with four replications and treatments were various concentration of wheat extract (0، 25، 50، 75 and 100%). At winter wild oat vegetative growth satge، treatments were 0، 25، 50 and 75 % of wheat aquatic extractconcentration and expriment was laid out according to Randomized Complete Block Design with four replications. Results indicated wheat aquatic extract application exhibited gradual rise inhibitory effect on seed germination، seedling weight، antioxidant enzymes activity and -amylase enzyme activity but elevated the mean germination time and malondialdehyde concentration in winter wild oat seedlings. Likewise، seedling weight، antioxidant enzyme activities and sucrose synthetesis enzymes activity were declined with wheat extract application but malondialdehyde concentration increased. In conclusion، wheat aquatic extract decreased seed germination، seedling growth، -amylase enzyme and sucrose synthetesis enzymes activity of winter wild oat.

The allelopathic effects of various concentrations (0 (as control)، 5 %، 10 %، 20 % and 40%) of berseem clover shoot extracts were assayed on germination and radicle growth of four weed species (Amaranthus hybridus، Amaranthus albus، solanum nigrum and chenopodium album) as completely randomized factorial with 3 replications. The effect of aqueous extract concentration of berseem clover on the mean germination time، radicle length and the equally germination was significant. S. nigrum had the highest germination percentage، the longest mean germination time، the highest radicle length and the lowest equally germination. A. hybridus had the lowest germination percentage، the mean germination time and A. albus had the highest equally germination. In total S. nigrum was the most resistant species and A. hybridus was the most susceptible species to aqueous extract of berseem clover.

In order to study the effect of different aqueous shoot extracts of four medicinal plants consist of: basil (Ocimum basilicum L.), jimson weed (Datura stramonium L.), summer savory (Satureja hortensis L.) and meliaceae (Melia azedarach L.) on seed germination and seedling characteristics of wild oat an experiment was conducted at Faculty of Agriculture, Ferdowsi University of Mashhad on 2010. A factorial arrangement based on completely randomized design with four replications was used. The experimental treatments were 4 different medicinal plant aqueous extracts as factor A, and extract concentration in 4 levels (0, 20, 40 and 60 percentage) as factor B. Results showed that medicinal plants aqueous extracts in different concentration had significant effect on measured characters. The highest and the lowest percentage and rate of seed germination, length of radicle and hypocotyle, dry weight of radicle and hypocotyle were obtained in treatments of control and aqueous extracts of datura, respectively. Percentage of seed germination, length of radicle and dry weight of radicle and hypocotyle difference were not significant in aqueous extract of Summer Savory compare with control. All concentrations of aqueous extracts significantly diminish all measured characters compare to control (0% concentrations). The lowest percentage and rate of seed germination were obtained in 60% concentration of all studied plant water extracts.

Recently weed scientist are more interested in weed management by allelopathy. The main objective of the study was to evaluate allelopathic potential of sunflower on redroot pigweed and common lambsquarter. this study was conducted in two series of laboratory and greenhouse experiments. Under laboratory conditions, leaf, stem and root aqueous extracts of sunflower at 0%, 2.5%, 5%, 7.5 % and 10% (m/v) concentrations were applied to determine their effect on redroot pigweed and common lambsquarter seed germination and initial growth under laboratory conditions. The results indicated that germination and mean daily germination was reduced by this extracts by 43% and 50% respectly. The effects of leaf and stem extracts on germination were more than root extracts of sunflower. The percentage and quality of germination was decreased by increasing the concentration of extracts. The root length and shoot length were reduced by 80% following application of sunflower extracts. In greenhouse experiments, to study the role of decomposition plant debris on release of allelochemicals, stem, root and leaf residues of sunflower were incorporated with pot soil by 5% (w/w) and weed seeds were sown and samples were taken in five stages of growth(2, 4, 6, 8 leaf and mature plant). Dry weight, leaf area and height of weeds were determined. The results of greenhouse experiments indicated that incorporation of sunflower residues in the soil (fresh or decomposed residues) reduced growth of redroot pigweed and common lambsquarter. The difference between fresh and decomposed residues was not significant. This study indicated that, fresh stem residues of sunflower are able to apply, its harmful effects on dry weight, leaf area and height of both weeds species.