Biological effects of essential oils and extracts
Hanieh Mohseni fazel; Karim Nozad namini; Hossein Hoseini; H. Zeinali
Abstract
Background and Objectives: Pigweed (Amaranthus retroflexus L.) is one of the most widespread weeds in the world, and regarding the amount of damage caused to crops, it is the third dominant dicotyledonous weed in the world. It is recommended to reduce the use of chemical herbicides ...
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Background and Objectives: Pigweed (Amaranthus retroflexus L.) is one of the most widespread weeds in the world, and regarding the amount of damage caused to crops, it is the third dominant dicotyledonous weed in the world. It is recommended to reduce the use of chemical herbicides through the replacement of non-chemical methods in sustainable agricultural management, and the use of plants' allelopathic effects is one of these methods. On the other hand, plants in different growth stages have different allelopathy sensitivity.Methodology: To evaluate the allelopathic effect of aqueous and alcoholic extracts of eucalyptus (Eucalyptus camaldulensis Dehnh) on Pigweed (Amaranthus retroflexus) growth stages, an experiment was carried out as a factorial based on a randomized complete block design with three replications in the greenhouse of Kashan Barij Essential Company, Iran. Treatments included aqueous and alcoholic extracts of eucalyptus (50, 75, and 100 %), controlled (0.002 concentration of 2,4-Dichlorophenoxyacetic acid, Ethanol 70%, distilled water), and three growth stages (five-leaf stage, seven-leaf stage, and stem elongation). The studied traits were measured in all three growth stages one week after treatments. To measure traits, ten plants were randomly selected from each pot. The studied traits included leaf length and width, total leaf wet weight, total leaf dry weight, stem wet weight, stem dry weight, stem length, root length, root wet weight, root dry weight, total plant weight, and shoot/root ratio. A ruler was used to determine the length and width of the leaf, the length of the root, and the length of the stem. Analysis of the variance of the data was done by MSTAC software. If the experimental factor was significant, the LSD test was used to compare the means.Results: Leaf width, total leaf fresh weight, total leaf dry weight, stem fresh and dry weight, stem length, root length, root fresh and dry weight, total plant weight, and shoot/root ratio were affected by the growth stage where the extracts were used. The effect of the concentration of aqueous and ethanol extracts of eucalyptus on leaf length and width, total leaf fresh weight, total leaf dry weight, stem fresh weight, stem dry weight, stem length, root length, root fresh weight, root dry weight, total dry plant weight, and shoot/root ratio was significant. Spraying at the stem and 5-leaf stages had the highest and lowest leaf width, stem length, and root dry weight, respectively. The extract application at the stem elongation and five-leaf stage had the highest and lowest leaf width, stem length, and root dry weight, respectively. The application of distilled water in the stem elongation phase produced the maximum leaf length (3.06 cm), total fresh and dry weight of plant leaf (1.00 and 0.2764 gr), stem fresh and dry weight (1.35 and 0.393 gr), and total fresh and dry plant weight (2.80 and 0.801 gr), respectively. The application of 75% concentration of eucalyptus ethanol extract at the 5-leaf stage produced the lowest total fresh and dry weight of plant leaf (0.188 and 0.0521 gr), stem fresh and dry weight (0.303 and 0.046 gr) and total fresh and dry plant weight (0.633 and 0.1157 gr), respectively.Conclusion: The aqueous and alcoholic extracts significantly decreased Pigweed growth indices, and its inhibitory effect was not significantly different in most traits with 2-4-D herbicide. The inhibitory effect of alcoholic extract on pigweed growth was greater than aqueous extract. Given that almost all eucalyptus extracts, either alcoholic or aqueous, significantly reduced Pigweed growth, it may be possible to reduce the pressure of this weed on crops by combining and using them as a bio-herbicide.
M. Dejam; R. Ataollahi; S. Sadat Khaleghi
Abstract
Worldwide, large amounts of herbicides are used for weed control. Problems due to the use of these herbicides have forced researchers to find more suitable methods for management of weeds. Some plants including Eucalyptus species have allelopathic properties that could be used in production of natural ...
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Worldwide, large amounts of herbicides are used for weed control. Problems due to the use of these herbicides have forced researchers to find more suitable methods for management of weeds. Some plants including Eucalyptus species have allelopathic properties that could be used in production of natural herbicides for weeds management. This investigation was performed in order to use Eucalyptus globulus Labill. leaf extracts to control Physalis alkekengi L. weed. The experiment included five types of solvent extracts consisting of aqueous, methanolic, ethyl acetate, acetonic and benzene and different concentrations of extracts at five levels (0, 1.25, 2.5, 5 and 10 gram per liter). Results showed that, in all solvent extracts, the inhibition level on germination and seedling growth increased by increasing the concentration of the extract. Among the extracts, methanolic and benzene extracts showed the highest allopathic effects, while aqueous and acetonic extracts showed the lowest one. According to the results, methanolic extract showed strong inhibitory effects on germination and seedling growth of P. alkekengi L. Therefore, it is possible to use methanolic extract at concentrations of 5 and 10 g/lit for controlling P. alkekengi L. Although benzene extract at high concentrations showed no strong inhibitory effect on germination, it was extremely effective in reduction of seedling growth that could be considered in management program of P. alkekengi L. control.
S.M. Hossaini; M. Aghaalikhani; F. Sefidkon; A. Ghalavand
Abstract
The Sahandi savory (Satureja sahendica Bornm.) is a native medicinal species of Iran, which is exposed to extinction. Organic farming of this species in low input systems has an important role to protect this valuable genetic reserve. To evaluate the essential oil content and components of the savory ...
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The Sahandi savory (Satureja sahendica Bornm.) is a native medicinal species of Iran, which is exposed to extinction. Organic farming of this species in low input systems has an important role to protect this valuable genetic reserve. To evaluate the essential oil content and components of the savory in natural habitat and field conditions, an experiment was conducted to investigate the plant growth responses to different fertilizer and redroot pigweed (Amaranthus retroflexus L.) density (0, 6, 12 and 18 plants/m2) in two planting patterns (rectangles, zigzag). The experiment was carried out in factorial based on RCBD with three replications at the Qazvin Agriculture and Natural Resources Research Center during 2010 to 2012. The nutrient treatments included NPK plus foliar application of micronutrients, four tons/ha vermicompost, two tons/ha vermicompost plus 40 liters/ha vermi-tea (liquid formulation of vermicompost). At the flowering stage, the essential oil content and compounds were measured in both samples of field and natural habitats. The effect of planting pattern was not significant. The highest content of essential oils in first harvest (28.38%) and in second harvest (46.04%) were obtained from organic fertilizer treatments, two tons vermicompost + 40 liters vermin-tea and four tons vermicompost, respectively. These treatments were superior to the savory harvested from natural habitats. The essential oil content of savory under competition of redroot pigweed at all densities were higher than the natural habitats and the highest content in first and second harvest (30.41% and 51.80%) was obtained at 18 plants/m2 pigweed density. In all fertilizer treatments, the content of thymol in comparison to natural habitats (38.49%) was superior and the highest content (42.95%) was obtained with application of four tons vermicompost. In the absence of weed, the Sahandi savory produced the greatest content of thymol (45.18%) compared to the savory grown in natural habitats.
