جستجوی مقالات مرتبط با کلیدواژه "weed" در نشریات گروه "بیوتکنولوژی و ژنتیک گیاهی"

Chickpea (Cicer arietinum) is very sensitive in competition with weeds and suffers from a decrease in yield and product quality. Therefore, it is useful to produce plants resistant to general herbicides such as glyphosate. In this research, Agrobacterium tumefaciens strain LBA4404 was used. This bacterium contains plasmid pBI121 and mutated epsps gene of Escherichia coli to create resistance to glyphosate herbicide. In this plasmid nptII gene is placed under 35S promoter as a selective gene. In order to transfer the gene, embryonic axes of chickpea varieties (Samin and Bivanij) were used. Chickpea embryonic axes were placed on B5 co-culture medium after co-cultivation with bacterial suspension for 3 days and then transferred to MS culture medium with appropriate concentration of BAP, Kin and NAA hormones for regeneration. Finally, after successive selections using kanamycin antibiotic, rooting and establishment of T0 plants were done in hydroponic environment. Then, PCR amplified epsps and nptII genes in 15 plants and their transgenecity was confirmed. Non-contamination of DNA in putative transgenic plants was confirmed by using the primers of the bacterial ITS regions. Also the expression of the target gene verified using RT-PCR test and the transgenic percentage was 0.75% in this study.

Weed in terms of the growth and the type of damage that cause and respond to different methods are different, you must first growth behaviors and response to environmental factors, the identification of various weed and then depending on the nature and behavior them the planning to manage the different species. One of the most important factors for successful weed seed germination that various environmental factors such as light, temperature, humidity, soil pH, salinity and drought stress is important, Response weeds varies is considerably in this respect. The competition started a weed that can be effective at an ecological niche. For being a weed able to compete for ecological niche germination is important.  

In order to assess the tolerance of this weed germination and seedling growth of weeds (Cardaria draba) and alyssum (Alyssum Hirsutum) ecotype Karaj to salinity and drought stress two separate trials in a completely randomized design with six treatments and four replications for each weed in weed Research Laboratory Bu-Ali Sina University Hamedan was conducted in 2015. On drought stress by solving a certain amount of polyethylene glycol 6000 for potential (-2, -4, -6, -8 and -10 Bar)  and Salinity by dissolving different amounts of sodium chloride in distilled water to create potential (-2, -4, -6, -8 and -10 Bar) and distilled water for each two experiments were used for without stress conditions. Seed disinfected with sodium hypochlorite (5%) for 2 minutes and then rinse with distilled water for 3 minutes, 25 seed inside diameter of 9 cm plate with two layers of filter paper were placed on the amount of 5 ml of distilled water or solvent with drought and salinity levels that were added to it. At the end of experiment characteristics of such as germination percentage, speed germination, seedling vigor index, seedling radicle and hypocotyl Length and weight were measured treatments.

The results showed that the drought and salinity from zero to -10 Bar decreased significantly (p<0.05) the percentage of germination, seedling vigor index, radicle and hypocotyl length, fresh and dry weight of seedling weeds. With increasing intensity of drought stress from zero to -10 Bar hoary cress and madwort seed germination was reduced 12 and 67 percent respectively compared to control. Madwort weed seed germination under drought stress was more than hoary cress plant. By capture both weed seed germination under salt stress and drought decreased madwort weed in germination was slow. Increased drought stress resulted in reduced seedling vigor in this weed. Highest (3.47) and the lowest (1.30) seedling vigor was observed at the controlled conditions and -6 Bar potential respectively and with increased the drought stress, there was no significant difference. Due to the loss of madwort weed seedlings at the above potential of -4 bars was not possible to measure seedling vigor. The salt stress caused to significant reduction in hoary cress and madwort seedling vigor. This index is a function of the germination percentage and seedling length and the fact that the stress seedling vanished, so the trait was not calculated. With increasing intensity of drought stress, the radicle and hypocotyl weight response in this weed was similar to alyssum. More decreased with increasing drought stress was observed in hory cress radicle. Highest hypocotyl and radicle growth in madwort weed was observed in control and drought stress had stopped growth radicle and hypocotyl seedling to stress and the destroyed after 15 days. According to the results seems to the germinated seeds of hory cress and madwort are highly sensitive to salinity and drought. However, the sensitivity to salt stress was higher the than drought stress in both weed. By comparing the two results show that madwort weed to drought and salinity stress this weed is more sensitive to stress as the minimum amount (-2 Bar) seedling growth processes were stopped.

In order to study interferential effect of lambsquarters (Chenopodiun album) on some of physiological traits and yield of marigold (Calendula officinalis), a factorial experiment was conducted in Islamic Azad University, Tabriz, Iran, based on randomized complete block design in three replications during 2014. Studied factors were weed densities (0, 2, 4, 6 and 8 plants per meter row) and its relative emergence times (along with crop, 10, 20 and 30 days after crop). Results indicated that in plots with 6-8 weed plants per meter row time to 12th leaf appearance in marigold delayed 5.3 days. In plots with only 2 weed plants, crop LAI value was similar to the control. Weed emergence time was more effective than its density on biomass. Crop biomass reduced 6.3 and 1.5 g m-2 per one weed plant increasing in meter row and one day earlier weed emergence, respectively. Weed competition had more negative effect on crop flower yield than its biomass. Lambsquarters could decrease crop yield when it was emerged with more than 4 plants per meter row. With considering of 5% permissible yield loss of marigold in competition with lambsquarters, its economic loss threshold determined when at least 2 weed plants per meter rowemerged 10 days after marigold and compete along with crop until late growth season. It was recommended to controlling of lambsquarters while at least to weed plants per meter row of marigold emerged before 10th day of emergence.

Given the importance of plant sasuseful sources for extracting newanti-bacterial andantioxidant compounds, thisstudy explored eight different plants species for antioxidantand antimicrobial properties. The methanol extract of the aerial parts of the samples was prepared by means of the maceration method. Afterwards, the antibacterial effects of the obtained extracts were analyzed by determining minimum inhibitory and bactericidal concentrations in the liquid cultivation environment. DPPH inhibition assay was appliedtoevaluate theantioxidant effect of the samples.The results indicated that Artemisiahas the bestantibacterial and Nepetacrassifolia (with IC50 = µg/ml 3.6) hasthe best antioxidant effect.

Different cardinal temperatures for germination has caused asynchronous appearance of weeds in fieldand so different appropriate management practices to control them, to avoid their invasion. So, in order to study the cardinal temperatures of germination in Atriplex dimorphostegia, Salsola crassa and Suaeda aegyptiaca seeds and effect of different temperatures on their germination characteristics, an experiment was carried out at research laboratory of Faculty of Agriculture in University of Birjand in 2013. The study was conducted based on completely randomized design with 8 levels of temperature (5, 10, 15, 20, 25, 30, 35, and 40○C) and 4 replications. The results of quadratic and dental models showed that cardinal temperatures of germination including base, optimum and maximum temperatures for Atriplex dimorphostegia were 5.57, 26.37, 47.07○C, for Salsola crassa were 3.48, 21.57 and 39.66○C and for Suaeda aegyptiaca were 6.96, 28.81 and 44.52 ○Crespectively. Effect of temperature on all indices of germination in all three weeds were significant (P<0.01) Reduction of percentage and rate of germination at the least temperature compare to the most temperatures in which germination was occurred, were 39.40% and 33.99 %, in Atriplex dimorphostegia and 86& and 66.29% in Salsola crassa and 87.04%, and 94.31% in Suaeda aegyptiaca respectively. The most germination uniformity was occurred at 20○C, 15-20 ○C and 20-40○Cin Atriplex dimorphostegia, Salsula crassaand Suaeda aegyptiaca respectively. Difference between minimum and maximum of Seedling shoot and root length, and Seedling fresh and dry weight were 94.52, 91, 85 and 98.57 percent in Atriplex dimorphostegia, 63.09, 70.12, 71.52, 53.85percent in Salsola crassa and 86.33, 93.99, 96.67 and 99.33 percent in Suaeda eagyptiaca r. The highest seedling vigor index was occurred at 20 ○C in Atriplex dimorphostegia and Salsola crassa and at 10 ○C  in Suaeda aegyptiaca.

The effect of salinity levels on germination and growth of sunflower (Helianthus annuus L.) cvs. Euroflor and Record and redroot pigweed (Amaranthus retroflexus L.) was studied in two separate experiments under laboratory and hydroponic conditions. The experiments were in split plot based on completely randomized design. Main plot and subplots were devoted for plant type and salinity level، respectively. The salinity levels were 0، 50، 100، 150، and 200 mM of sodium chloride in laboratory condition. The seeds were placed in each Petri dish separately and 5 ml of salt solution was added and were incubated at 30 °C. The germination and primary growth parameters were evaluated in one week. Increasing salinity levels، caused reduction of germination percentage and seedling growth parameters of sunflower cultivars and redroot pigweed، significantly. The redroot pigweed was less tolerant to salinity than sunflower cultivars in germination stage. In hydroponic condition، the seeds were sown in sand and after plant transferring to Hoagland solution، salinity treatments including 25، 50، 100، and 150 mM of sodium chloride were added to the culture medium. After 4 weeks، the growth parameters and leaf chlorophyll content were recorded. The growth parameters and leaf chlorophyll content were decreased significantly، increasing of salinity levels. In addition to the sunflower cv. Euroflor was less tolerant to salinity than Record and redroot pigweed. The sunflower cv. Record is recommending being cultivated in saline soils.

In an attempt to investigate the effect f nutsedge (Cyperus spp. L.) density on yield and some of the yield components of the traditional and improved rice cultivars of rice, a field experiment was conducted at Agricultural Sciences and Natural Resources University of Sari in 2011. The treatments included four levels of the abovementioned weed (control, 60, 120, and 180 plants per square meter) and three rice cultivars (Tarom, as the traditional cultivar, Shirodi and Ghaem as improved cultivars). The study was carried out in factorial based randomized complete block design with three replications. The results of ANOVA indicated that there was a highly significant difference between weed density, cultivars, and their interaction in terms of fertile tiller number, plant length, filled and unfilled grain number, days remaining to 50% flowering and maturity, 1000 grain weight, panicle length, grain figure, and biological and grain yield. On the basis of the means comparison, the highest amount of plant height (122cm), 1000 grain weight (24.49 g), filled grain number (108 grains per panicle), and panicle length (28 cm) was observed in Tarom. The maximum of days to 50% flowering and maturity (113 and 122 days, respectively), tiller number per hill (23), fertile tiller number, biological and grain yield (1800 and 740 g m-2, respectively) was recorded for Shirodi cultivar in control treatment. The minimum amount of these traits belonged to 180 yellow nutsedge per square meter. The results also indicated that the competitiveness of the rice cultivars was significantly different in various weed densities.. Generally, the results of this experiment indicated that yellow nutsedge had high competitiveness ability even in low density and that an increase in the density of this weed up to 180 plant per square meter significantly and linearly reduced the yield and yield component of rice cultivars. Nevertheless, Tarom cultivar had the best competitive index in different nutsedge density due to its good physiological and morphological parameters.

The effects of sowing date, and weed interference on main agronomic characteristics of lentil varieties was investigated in a field experiment in Khorramabad during 2005-06 growing season. The experimental design was a randomized complete block in factorial arrangement with 4 replications. The experiment had 3 factors including: weed interference at two levels (weed free, and weed infested throughout the total growing season), planting date at three levels (autumn, winter, and spring) and three lentil varieties (Gachsaran, Flip93-93, and Lorestan landrace). Lentil biomass yield in autumn planting date was 21.6 and 155.8% more than that in winter and spring planting dates, respectively. Control of weeds, lentil biomass increased by 34.7%. Maximum grain yield (1486 kg ha-1) was achieved in autumn planting date, that was significantly more than two others sowing dates. Lentil grain yield for autumn planting date was 28 and 297.6% more than yield of winter and spring crop respectively. Yield of Gachsaran and Flip cultivars were significantly more than that of Lorestan landrace. Weeding increased lentil grain yield by 46.7%. Weed control caused 48.4, 50.3, and 30.1% increase in grain yield for autumn, winter, and spring sowing dates respectively. Yield losses due to weed interference for Gachsaran, and Flip cultivars were 54.7, and 47.6%, respectively. However there were not significant differences between weed free and weed infested situation for Lorestan landrace. Maximum grain yield (2394 kg ha-1) achieved in autumn sowing by Gachsaran cultivar at weed free treatment. Minimum yield belonged to spring crop of Lorestan landrace in weed infested situation.