جستجوی مقالات مرتبط با کلیدواژه "طول ریشه چه" در نشریات گروه "زیست شناسی"

Germination, growth, yield and quality of crops are determined by seed material, which can be ‎‎improved by pre-planting treatments with the participation of various physical factors including ‎‎electric field, magnetic field, laser radiation and microwave radiation. Stimulation before sowing ‎seeds with a magnetic field includes a constant magnetic field generated by permanent magnets ‎and electromagnets, as well as a variable magnetic field. The variable magnetic field is generated ‎by specially designed electromagnets. The biological behavior of seeds, roots, pollen grains and ‎buds of some plants changes under electromagnetic fields. For this reason, studies have been ‎conducted on the side effects of this field on the germination response and seedling growth and ‎yield in some plants. Plant cells have a negative charge that can absorb positively charged ions. ‎Cytochemical studies have shown that root cells exposed to a weak magnetic field compared to ‎control cells show a state of calcium saturation in the cytoplasm of all their organs. Magnetic ‎fields affect both the activity of ions and the polarization of bipolar molecules in living cells. The ‎magnetic field also stimulates cell metabolism and mitosis in cells. Meristematic plants become ‎plants. Variable magnetic fields, if used properly, have a great stimulatory effect on cell ‎proliferation and the growth of plants and fungi. According to studies, the use of ‎electromagnetic field may also affect the seed germination of medicinal plants and improve seed ‎germination, but taking into account that the intensity and duration of these pretreatments It can ‎have different effects in different seeds, it is better to do studies with different intensities and ‎durations of these treatments before recommending these methods for commune failure. Due to ‎the great medicinal properties of Echinacea and the lack of information about the effect of these ‎treatments on germination of this species, the aim of this study was to investigate the germination ‎of Echinacea seeds after electromagnetic field treatments.Therefore, the aim of the ‎present study ‎was to investigate the germination of Echinacea seeds after electromagnetic field ‎treatments. ‎

In order to investigate the intensity of 100 ms and the duration of the magnetic field on the ‎germination components of Echinacea seeds in the laboratory of production and processing of ‎medicinal plants, Faculty of Agriculture, University of Tabriz in a completely randomized design ‎with three replications in 2015 Done. Experimental treatments included a constant magnetic field ‎strength (100 ms) and the duration of exposing the seeds to a constant magnetic field for 5, 10, ‎‎15, 20, 25, 30, 35, 40, 45, 50 and 55 minutes and control treatment (without magnetic field ‎exposure). The dried seeds were placed in batches of 75 in a thin transparent plastic tube between ‎the poles of the magnet with a constant magnetic field strength and time required, and then ‎placed in batches of 25 in each petri dish. To apply the magnetic field, a magnetic field inductor ‎was used, which consisted of a pair of magnets with the ability to adjust the distance from each ‎other. The two magnets were embedded in the machine so that they were attracted to each other. ‎The distance between the two magnets was adjusted by measuring the intensity of the magnetic ‎field with a teslamter device so that the magnitude of the magnetic field was 100 milliseconds. ‎First, the seeds were disinfected by soaking in 10% sodium hypochlorite for three minutes and ‎then washed several times using distilled water to remove residual sodium hypochlorite from the ‎seed surface. In this experiment, after applying the treatments, 25 seeds of each treatment were ‎placed in three replications in a nine-centimeter dish with a Whatman filter paper. The petri ‎dishes were then placed in a germinator at 22 ° C for 12 hours for germination for 15 days. The ‎number of germinated seeds (2 mm rootlet exit was considered as germination criterion) was ‎counted and recorded daily. On the last day, to obtain the length of the root and stem, first the ‎root was separated from the stem and their length was measured with a ruler, as well as the fresh ‎weight of the root and stem. Which was calculated by the scales with an accuracy of 0.001 and ‎then to obtain the dry weight of the samples, after weighing, they were placed in an oven at 70 ° ‎C for 24 hours and finally the weight Their dryness was calculated by a scale with an accuracy of ‎‎0.001. Also, ratio of root length to stem length, ratio of root dry weight to fresh weight of root ‎and ratio of dry weight of stem to fresh weight of stem Was calculated. The following equations ‎were used to determine the germination rate (GS) and germination percentage (G%).‎

The results of analysis of variance showed: root dry weight, shoot dry weight, germination rate, ‎ratio of root dry weight to fresh root weight and ratio of stem dry weight to fresh weight of stem ‎At the level of 1% probability and fresh weight of stem, root length, germination percentage and ‎ratio of root length to stem length were significant at 5% probability level and fresh weight of ‎root And shoot length was not significant. Comparison of means showed that the highest fresh ‎weight of shoots in 15 minutes treatment (exposure to magnetic field), highest dry weight of ‎shoots and shoots, root-shoot length, germination percentage And germination rate and ratio of ‎root length to stem length in 15 minutes treatment (exposure to magnetic field) and maximum ‎root dry weight to root fresh weight and stem dry weight to Stem fresh weight in 20 minutes ‎treatment (magnetic field exposure) and the lowest amount of root and stem fresh weight, root ‎dry weight, root length, ratio of root length to Stem length and shoot to dry weight ratio of shoot ‎to fresh weight in 50 minutes (exposure to magnetic field), minimum shoot dry weight and shoot ‎length in 30 minutes (exposure Magnetic field exposure), the lowest percentage and germination ‎rate in 20 minutes treatment (magnetic field exposure) and the lowest ratio of root dry weight to ‎fresh root germ weight in control (without exposure Magnetic field) was observed. Based on the ‎results obtained from the comparison of means, 10 minutes of treatment (magnetic field ‎exposure) had the greatest effect on the measurement components compared to the control.The ‎magnetic field not only allows water to penetrate the seed faster, but also affects the rate of ‎enzymatic reactions. Increased water absorption in the first stage caused the inflammation of the ‎seeds to be affected by the magnetic field, which resulted in an increase in their fresh weight. ‎The magnetic field reduces the surface tension and viscosity of water, as well as the latent heat ‎of vaporization, which eventually leads to rapid evaporation of water. These three phenomena are ‎related to the power of action designated as hydrogen bonding. Changes in these indices lead to ‎faster penetration of water into the seeds, causing faster and more effective germination of seeds.‎

Salinity is one of the most important problems of abiotic stress in plants, which prevents seed germination, seedling growth and productivity reduction. Germination is a complex phenomenon that includes physiological and biochemical changes that are the result of embryo activity. Salinity is one of the most important environmental factors that reduce the growth and performance of plants and is a state of soil characterized by a high concentration of soluble salts. Studies on the effect of salinity have shown that in many plants, with an increase in salt concentration, germination indicators decrease and plant growth decreases. Germination is the first and most sensitive stage of plant growth and development, in addition to that, the uniformity of germination, the average time of germination and greening are also important parameters of seed quality. One of the studied species is woolly grass (Bromus tomenolus Boiss.), a perennial and stable plant, very palatable, strong and permanent with dense and many roots, which often grows in cold semi-arid climates and is one of the best mountain wheats for breeding and development. Summer meadows are considered. This plant prefers shallow to deep soils, light to medium texture, without salt and alkali. Persian clover (T. resupinatum) belonging to the genus Trifolium is one of the most important fodder plants of the Leguminous family in temperate and humid regions, which has great value as fodder and pasture and plays a significant role in livestock nutrition. The main factor that effects on plant growth in arid and semiarid areas is salinity. In view of saline lands increasing in arid and semi-arid regions of Iran, is necessary finding the potential of plant species due to soil salinity changes in different climates

The first habitat is the north-eastern summer pastures of Harsin city, Kermanshah, whose average altitude is 2000 meters above sea level. The long-term average rainfall is 369 mm, and the climate of the semi-arid region is ultra-cold. The second habitat is a part of Golugah pastures located in Mazandaran province. Its maximum height is 2650 and minimum 2150 from the sea level and the average slope is about 25%. Its average annual rainfall is 383 mm, the highest amount in autumn and the lowest amount in summer. Its average annual temperature is 12.44 degrees Celsius. The climate of the semi-arid region is cold with mild summers and cold winters. In order to determine the resistance of the early growth stages of these species under different salinity stresses, an experiment was conducted in the form of a completely randomized design with 10 replications and 6 treatments. In order to create salinity stress, sodium chloride (NaCl) solution was used at zero (control), 50, 150, 25, 350 and 450 mM levels. Before placing the seeds in the Petri dish, they were disinfected by placing them in 5% sodium hypochlorite solution for 3 minutes and then washed with distilled water. 20 seeds were placed in each petri dish covered by filter paper. Salinity treatments were investigated for 20 days in laboratory conditions at 25°C with light conditions of 14 hours a day and 10 hours at night. During 20 days, the number of germinated seeds was counted every day, and at the end, characteristics such as the percentage and speed of germination, the length of root and plant were measured. In order to calculate the average length of roots and plants in each Petri dish, measurements were made and the average number was recorded So, this research was studied the effect of salinity levels on germination properties of Bromus tomentellus and Trifolium resopinatom in two different habitats, Mazandaran and Kermanshah. For this, collected seeds of these species were grown in laboratory. 20 seeds were tested in Petri dish under salinity stress as control, 50, 150, 250, 350, 450 MM and germination percentage, germination speed, rootlet, seedling were measured.

The T-test was used for determination of mean difference between two species in SPSS 22 software. The result showed that seeds of Tr. resopinatom in Kermanshah have more resistant to this species in Mazandaran and the Br. tomentellus seeds were in the opposite. In the studied treatments Br. Tomentellus seeds of Mazandaran had more resistant and Tr. Resupinatum had less tolerance to salinity.The results of the average of all three factors measured for Pashmeki grass and Iranian clover species in both regions showed that the highest amount of factors is present in the control treatment and with increasing salinity concentrations, germination percentage, germination speed and root length What is reduced? They stated that high salinity stops germination, growth of roots and stems. The reason for this is the physical and chemical effects or the toxic-osmotic effects of the solutes in the saline solution. In fact, with the increase in the salinity of the environment, the osmotic pressure (the osmotic potential becomes more negative) increases, which causes the disruption of the seed dehydration stage, and on the other hand, the presence of a high concentration of anions and cations (especially sodium and chlorine) in the environment, with Causing poisoning in seeds prevents seed germination. Considering that the climate of the two seed collection areas is different, it seems that plant seeds are affected by the climatic conditions of the origin region, he also stated that tolerance to salinity, in addition to the physiological complexities and structure of plants, depends on various factors such as temperature. It depends on the environment, plant growth stage, soil and water composition, environmental variables and plant variety. stated that the natural conditions of the habitat are effective on the growth and germination of different species, therefore, the different results of the studied parameters in different habitats can be justified.Considering that some studies stated that the germination tolerance of plant species in saline environments under laboratory conditions is not necessarily the same as the response to salinity under field conditions; Therefore, it is suggested that the studied species should be cultivated under free environmental conditions to be able to introduce their seeds for the restoration of a specific area in principled decision-making.

In order to investigate the effect of seeds priming of Astragalus adscendens with Rice bran extract and potassium nitrate (Nano-Se) solution in the early stages of germination, a factorial experiment was conducted in a completely randomized design (CRD) with four replications conducted at the botany Lab of the Department of Biotechnology, University of Kashan, in 2017. Experimental treatments consisted of priming with Rice bran extrac solution at 4 levels (zero as control, 0. 1, 0.2 and 0.5 (percentage of weight - Volume: w/v), and Nano-Se in 4 levels (zero as control, 0.04, 0.08 and 0.1) w/v for 2 hours at 25 ° C. The results of the experiments showed that Rice bran extract, Nano-Se solution and interaction of treatments were significant at the 1 % level on all studied traits, including germination percentage, root length, stem length, germination coefficient, relative content of water, chlorophyll a, b and total chlorophyll content. Also, the use of rice bran extract 0.1% increased the 15%. of root length but with Increasing the concentrations of bran extract root and shoot length decreased compared to control. Also, seeds priming with rice bran extract 0.2% and Nano- Se 0.8% increased the root length 37%. The highest germination percentage, the content of chlorophyll a and b, and stem length were obtained by applying 0.11% w / v Rice bran extract solution with 0.1% w/v of Nano-Se . Also, applying these treatments alone had positive and significant effects on the studied traits.