تأثیر آب مغناطیسی و تنش شوری بر خصوصیات جوانه‌زنی و رشد گیاهچه لوبیا (Phaseolus vulgaris L.)

Introduction
Increasing world population is facing critically depletion of water resources, which will be along with increasing food demands to cover the human needs all over the world. Therefore, water scarcity is increasingly a major limitation for increased agricultural production and food security in this century. The scarcity of qualified water, has made farmers to consider the water of marginal quality for usage in agriculture. The Water’s molecular structure is affected by a magnetic field, so that a change in the water relations can affect the overall plant growth. One of the approaches that provides higher productivity and quality assurance is using static electromagnetic fields. The use of magnetically treated water for irrigation in agriculture is considered as one of the important environmental clean methods. The water treated in the magnetic field or pass through a magnetic device called magnetized water. The influence of magnetic field on various growth processes of plants such as seed germination, seedling growth, plant growth, yield and the properties of crop quality have been the object of several researches.
Salinity is defined as the presence of excessive concentration of soluble salts in the soil or in the irrigation water that suppresses plant growth and eventually yield. Salt stress has been identified as one of the most serious environmental factors limiting the productivity of crop plants. The deleterious effects of salinity on plant growth are associated with 1) low osmotic potential, 2) nutritional imbalance, 3) specific ion effect, or 4) a combination of these factors. In addition, there is evidence that salt stress can induce oxidative stress due to generation of reactive oxygen species.
Phaseolus vulgaris is an annual growing to 2 m height and is frost tender. Bean leaves are trifoliate (three-leaved), arranged in an alternate fashion on the stem and have oval or diamond-shaped leaflets. Leaf color can be green. The study was undertaken to evaluate the use of magnetically treated water in improving seed germination and early seedling growth (i.e., radical and plumule growth) of the bean (Phaseolus vulgaris L.) in the presence and absence of salt stress. The work was carried out at the germination stage because germination is known as a key process that allows the seed embryo to grow and evolve into photosynthetic organism, and it is also a critical stage for plant response to salinity.

Materials and Methods
In order to investigate the influence of magnetized water and salinity on germination characteristics and seedling of bean (Derakhshan variety), an experiment was conducted based on complete randomized design in factorial arrangement with four replications at laboratory of the Agricultural College of Ferdowsi University of Mashhad in 2014. Water types consisted of two levels (magnetized water and tap water) and five salinity levels: 0, 4, 6.5, 8.5 and 9.5 ds/m.
The following indices were also measured:
Final Germination Percentage (FGP) and Germination Rate (GR) was calculate base on the below equation
FGP= (n / N) × 100
where n is the number of seed germination in per day and N is total number of seeds
GR=
where giis the number of seed germination in every count and di is the number of days till day n th.
(Dere and et al., 1998) Chlorophyll concentration was calculated using the following formula
Chla (μg/ml) =15.65 A666 - 7.340 A653
Chlb (μg/ml) =27.05 A653 - 11.21 A666
Cx+c=1000A470 – 2.270 Cha – 81.4Chb/227
Traits as length and dry weight of plumule and radical, biomass and seed vigor index were measured too.
Data was analyzed using MSTAT-C software and means were compared using Dunkan multiple range test in 5 percent probability.

Results and Discussion
The results showed that germination percentage, mean germination time, length and dry weight of the plumule and radical, biomass and seed vigor index decreased with increasing salinity, but magnetized water improved them. Magnetic water increased germination by 6% and reduced the mean germination time by 8%. Magnetized water improved biomass and seed vigor by 52 and 24 percent, respectively. Using magnetic water, improved radical length and plumule by 27 and 24 percentage, respectively. The simple effect of magnetized water and salinity caused significant amounts of chlorophyll a and b and carotenoid. Application of magnetic water increased chlorophyll a (12%) in the salinity level of zero compared with non-magnetic. So that magnetized water improved amount of chlorophyll a and increased carotenoid under salinity conditions. Other results showed that plant cells treated with magnetic represent magnetic properties of atoms placed in them and activates them later on.

Conclusion
Overall, results showed that exposure to magnetic fields and irrigation water with different salinity levels, decreased salinity (NaCl) effects on bean, accelerated germination and seedling growth and had an important role in improving the beans germination rate.