جستجوی مقالات مرتبط با کلیدواژه "دگرآسیبی" در نشریات گروه "جنگلداری"

Allelopathy is the interaction between plants that stimulates or inhibits the growth and germination of other species. Non-native species of (Prosopis juliflora (SW.) DC) is one of the species known as invasive species with allelopathic effects that can inhibit the growth and growth of species by producing allopathic compounds such as phenols, alkaloids into the environment. Two important species of Hormoozgan province are Acacia oerfota and Acacia tortilis which P.juliflora was observed with them in the natural forests, Therefore, the correct selection of tree species in forest plantation should be done with caution in order to inhibit negative effects on native species. The aim of this study was to investigate the allelopathic effects of different organs of p. juliflora on germinatin, radicle and plumule length of Ac. tortilis and A. oerfota.

For this purpose, the organs (root, bark and leaf) of P.juliflora were collected and different extract concentration (0, 2, 4, 6 and 8%) were prepared were added on A.tortilis and A. oerfota (4 replications, n=60) in growth chamber, and after recording germination, the plumule and radicle length were meausered after 30 days. Factorial experiment was performed through completely randomized design and was analyzed by two-way variance analyses.

Results showed that the lowest gemination percentage in A.tortilis was observed at 8% concentration with the amount of 16.11%. The plumule length of A. tortilis and A. oerfota in aquatic extraction of leaves (1.73 and 3.9 cm) was significantly lower than other organs. Also, the plumule length of A. tortilis (3.58 cm) and A. oerfota (5 cm) had the highest amounts in control. The interaction effects of organ × concentration showed that plumule and radicle length in A.tortilis and A. oerfota had the significant differences. The interactions of organ × concentration on radicle and plumule length in A.tortilis and A. oerfota species were also significantly different. The radicle and plumule length of A. tortilis and A. oerfota in leaf organ with values of 1.25, 1.73 cm and 1.98 and 3.9 cm were significantly less than bark and roots, respectively.

The results showed that there were inhibitory effects of aqueous extract of Prosopis juliflora root, bark and leaves on the germination percentage, root length and stem length of two important species of Acacia tortilis and Acacia oerfota in laboratory condition. Among the three studied organs, the leaf organ had the most inhibitory effects, which due to the high volume of litter under the canopy of this species in the environment and the entry of toxic compounds into the surface soil due to decomposition, prevents the growth of Acacia tortilis and Acacia oerfota that P. juliflora is seen with these species and overcome on them. Also, the root had the lowest inhibitory In according to the results, P.juliflora has allelopathic effects on native species. Therefore, it is recommended to choose non-native species for afforestation more carefully and using native species for reforestation and afforestation in the south fragile ecosystem of Iran is more suitable option.

Despite the initial need of seeds and seedlings of grey mangroves (Avicennia Marina (Forssk.) Vierh.) for semi-shade, they are very low under the canopy of trees of this species in Hormozgan province, Iran. For this purpose, in this study, the effects of possible inhibition of pneumatophores and leaves of mangrove trees on the vegetative characteristics of grey mangrove seedlings in greenhouse conditions have been investigated. After collection of propagules from healthy mother trees and cultivating them in September 2020, propagules were irrigated with concentrations of 0, 0.05, 1 and 2% of leaf and root extracts. After six months, the vegetative and biomass characteristics of mangrove seedlings were measured in different treatments and evaluated using two-way analysis of variance and Duncan test. The results showed that the diameter of growth (5.58 mm), height (29.27 cm), root length (27.73 cm), number of leaves (14.58) and root fresh weight (5.65 g) were the highest in the control treatment. Also in control and 2% treatment, root dry weight (1.02 and 0.77 g), stem fresh weight (12.77 and 10.59 g), stem dry weight (3.54 and 2.93 g), root water (4.62 and 3.29 g) and stem water (9.23 and 7.66 g) had the highest and lowest values, respectively. Investigation of organ × concentration interactions showed that leaf extract had a significant reduction effects on root fresh weight and root water in 2% treatment compared to those in the other treatments. According to the results, increasing of leaf and root extracts concentration of grey mangrove trees has a inhibitory role on the vegetative characteristics of seedlings of this species, so in reforestaion and afforestation of gery mangrove trees, the seedlings should be planted at a suitable distance from the trees.

The aim of this study was to investigate the allelopathy effect of Prosopis juliflora species on emergence, vigority, gemole and plumule length of two important forest species in southern Iran, Hormozgan province. For this purpose, in the summer of 2020, 15 seeds of Acacia oerfota and Acacia tortilis were planted in the soil collected under, margin and four meters from the canopy edge of Prosopis juliflora and also in the soil mixed with leaf powder of Prosopis juliflora (0, 20, 40, 60 and 80 gr/kg leaf powder in soil) and irrigated with distilled water and their emergencewas recorded once every two days. Finally, gemole and plumule lengths of germinated seeds were measured and the variables were analyzed using GLM statistical analysis at 95% level. The results showed that the emergence percentage in A. tortilis species (20.74%) was significantly higher than A. oerfota species. The gemole length of A. oerfota species (5.14 cm) was longer than A. tortilis while in the soil mixed with prosopis leaf powder, the gemole length in A. oerfota was lower (0.53 cm) than it in A. tortilis. The length of gemole and Plumule in the open area with values of 5.88 and 4.34 cm was significantly higher than their values in the soil under the crown of Prosopis juliflora. Emergence percentages (17.5%), vigority (13.40) and the length of plumule (4.22 cm) were lower in the soil mixed with prosopis leaf powder than those in control treatment. The interactions of species×soil position on vigority (4.40), gemole and plumule length (3.11 and 2.48 cm) showed that the two variables of gemole and plumule length were affected by the soil collection site and had its lowest value under the canopy which it was observed in prosopis leaf concentration treatments. The results showed that A. oerfota species was strongly influenced by Prosopis juliflora allelopathy, therefore, it is recommended to prioritize afforestation with native species and, if possible, to avoid the plantation of Prosopis juliflora in the southern sensitive ecosystems.

The current study evaluated the allelopathic potential of the Persian silk tree (Albizia julibrissin) leaf residues on seed germination and biomass attributes of the Tree of heaven (Ailanthus altissima) seedlings. An experiment was conducted based on a completely randomized design by eight replications. Experimental treatments consisted of different levels of leaf residues at concentrations of 0%, 2.5%, 5%,and 7.5%.Germination index was used in order to investigate the effect of allelochemicals on seeds germination. In addition, the effect of allelopathic materials on seedling biomass was measured by calculating the parameters of collar diameter, fresh and dry weight of seedlings, root dry weight, number of leaves, seedling weight vigor index and percentages of seedling water content index. The results revealed that seed germination index, seedling dry weight, seedling fresh and dry root weight and seedling weight vigor index significantly decreased at different concentrations of leaf residues compared to control, but the increase in concentration had no significant effect on these attributes. But higher concentrations of leaf residues had stronger inhibitory effects on seedling collar diameter, fresh seedling weight and the number of leaves per seedling. The present study clearly proved the allelopathic effects of the Persian silk tree (Albizia julibrissin) leaf residues on biomass attributes of the Tree of heaven (Ailanthus altissima) seedlings. In addition, the Persian silk tree (Albizia julibrissin) leaf residues can be used to control the irregular growth of Tree of heaven seed as an invasive species, as well as weed management in agroforestry systems which require further studies.

Afforestation with native or non-native species affects understory vegetation. These effects, besides of edaphic and climatologic factors, also depend on the species of the plants which are used. In the present study, the allelopathic effects of two species of Eucalyptus (E. camaldulensis Dehnh. and E. microtheca F.Mull.) and one species of Acacia (A. salicina Lindl) on the understory vegetation in Shiraspary region, Mamasani (Fars province) were studied. Aqueous extraction of leaves of these species was prepared in the laboratory; the effects of different densities of these extractions on the vegetative factors of Avena fatua L., Lolium perenne L., were investigated. The maximum inhibitory effect was on radical length and the minimum inhibitory effect was on seed germination. 5% density of these extractions had a stimulatory effect on the seed germination. The highest inhibitory effect on Lolium perenne was on E. camaldulensis, A. salicina, while the least inhibitory effect was on E. microtheca. The highest inhibitory effect on Avena fatua germination was on E. camaldulensis; the least inhibitory effect was after exerting A. salicina. 5% density of E. camaldulensis showed a stimulatory effect on radical growth. The 5% density of extractions increased the plumule length. The maximum inhibitory effect on the length of Lolium perenne was on A. salicina, E. camaldulensis, while the minimum inhibitory effect was on E. microtheca. The maximum inhibitory effect on length of Avena fatua was on E. camaldulensis, and the minimum inhibitory effect on radical length was on E. microtheca, A. salicina. The minimum inhibitory effect on plumule length originated from A. salicina. Compared with the control, the allelopathy effect of two Eucalyptus species was more than that of the Acacia. Both the stimulatory and inhibitory effects coincide with each other, indicating the presence of both types of allelochemicals which are capable of enhancing and suppressing at the same time. However, toxic allelochemicals are more volatile in nature than the stimulatory allelochemicals. This increased the competition ability of eucalyptuses and caused them to dominate forests and woodlands. Eucalyptus should not be cultivated in sensitive and especially arid ecosystems, so that the allelopathic effects of this species can be minimized.