عنوان مقاله [English]
Introduction Plants are able to respond to stresses or environmental factors. Application of electricity, magnetism, monochromatic light and sonic waves for increasing growth rate is called electro-culture. These factors can affect growth of plants. Many studies have shown that magnetic fields can affect the organisms. However, the exact mechanism of this effect is still unclear. A description of possible multiple effects of magnetic field on living organisms is oxidative stress due to increased production of oxygen species that is with the mediation of iron. considering the development of the lawn field in the country and the value of this plant, the aim of this study was to investigate the influence of magnetic field on the growth of grass seeds and determine how to optimize the magnetic field.
Materials and Methods In this study, the effect of AC magnetic flux density and exposure time of magnetic field on germination of grass seed (Festuca arandinacea) was investigated using an electro-culture system. Helm Holtz coils were designed to a create uniform field in the electro-culture system. Helmholtz coil radius and its average height were 18 cm, consisting of two coils to create a uniform magnetic field strength. Pulleys were made of polyethylene. After construction of pulleys, 500 turns copper wire with 1 mm diameter was wrapped around the pulleys. In the coil design, dimensions and materials were selected such that they could bear the weight of the wires and the created heat. In order to create distance between the coils, four stands were used. The stands had possibility of changing their length. Sinusoidal alternating magnetic field was created by applying 50 Hz alternating current to the coils, which were connected in series circuit. Magnetic flux densities were 0.1 and 1 mT, exposure times were 15, 60 and 240 minutes and there was a control treatment (without magnetic field). The design was completely randomized with four replications For evaluation of the electro-culture system, germination percentage, germination rate, mean germination time, and shoot length of every treatment were measured. The current of the coils was controlled using Varyak (an electrical transformer with only one coil for voltage control). Multi meter was attached in series between Varyak and Helm Holtz coil. Tesla meter was applied for measurement and detection of the magnetic field. Electromagnetic flux density 0 (for control), 1.0 and 1 mT at duration of 15, 60, and 240 minutes was applied to the grass seeds. Germinator was used with 13 hours of darkness, and 11 hours of light at constant temperature 20 ± 2° C, respectively. Daily counting of the germinated seeds was done for a week and at the specified time. More than two millimeters root seeds were counted as germinated seeds. On the last day, shoot length for at least five explants from each repeats was measured. Then all data was analyzed using SPSS software and factorial test. The analysis of variance and the mean comparison (Duncan) were performed for the data.
Results and Discussion For the mean time of germination, due to the lack of significant interaction between factors, the main effect of magnetic flux density was studied. But for other indices, mean comparison was done for the interaction effects too. Generally, increase of exposure time could improve germination. The best treatment was application of 1 mT magnetic field for 60 minutes. The results showed that magnetic field had a significant influence on the measured traits and most of them showed better results comparied to the control treatment. Coparison between control and optimal treatments, showed that germination percentage, germination rate, mean time germination and shoot length improved to 124%, 155%, 8% and 64% respectively. Maximum rate, germination percentage and shoot length of grass seed obtained at 1 mT magnetic field with 60 min exposure time. Grasses have high water requirements during germination and growth and they must be irrigated constantly. If the condition of growth and germination improves, the water could be saved. Magnetic field can affect exchange of ions in the cell membrane. Distinction of this effective mechanism in electric culture requires more studies by researchers of biology and other related areas. The most investigations should be done to study the effect of magnetic fields on germination by magnets or direct current which is usually easy to create, while in this study the alternating field could have different effects. The other advantage of the system is its ability to create a uniform magnetic field and the possibility to create different fields through changing the current.
Conclusions An electro-culture system was designed using alternating magnetic field to stimulate early growth of grass seed as a non-chemical, non-invasive and non-destructive driving factor in the growth. It seems electromagnetic field application can improve cultivation of grass seeds. Further is still needed in this area; the effect of fields from 2 to 4 mT at 60 to 240 minutes should be studied. However, for germination tests, a large number of treatments may lead to reducing accuracy and in this regard limitations should be taken into consideration. Further tests are needed to investigate this new approach.