Effects of ozone depletion and increase of UV radiation have been studied by many researchers. The aim of this study was to investigate the effects of UV-B radiation on Melissa officinalis L. as well as the impact of salicylic acid and magnetic fields in the reduction of harmful effects of radiation on plants. The Melissa officinalis L. plants were treated with 28 ± 2 Cº for approximately 60 days. The light intensity was 150 µ E mˉ² Sˉ¹ and the light/dark regime was 16/8 h. UV-B treatment was applied after the six-leaf stage for a period of 15 days and 20 min every day. Salicylic acid (1mM) was daily sprayed on the plants after the six-leaf stage for one week. Magnetic field treatment was applied for an hour with intensities of 0, 40 and 85 mT. The results indicated that the UV-B radiation led to reduction of root and shoot dry and fresh weights, and root and shoot elongation. The radiations also reduced the content of photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoid), sugar and soluble proteins. The phenylalanine ammonia-lyase activity and UV-absorbing content compounds increased under the effect of UV-B radiation. The results showed that treatment with salicylic acid and magnetic fields reduced damages to the plant due to UV-B radiation. 

Melissa officinalis is a medicinal plant belong to  lamiacea family.  This plant has been cultivated in many parts of the world due to its therapeutic effects. This study was conducted to improve antioxidant activities of proliferated shoots from tissue culture. The seeds of plant   were cultured in MS hormone free medium in order to obtain   seedlings. Then the  shoots were transfer to MS medium supplemented with 2 mg/ L  BAP.After 45 days salicylic acid (SA) was added to the medium at concentrations of 0, 50, 100 and 200 µM. The antioxidant activity and phenolics, flavonoids and rosmarinic acid content in proliferated shoots were evaluated 4,7,10 and 14 days after treatment. As a result the highest free radical scavenging and reducing power activity, as well as the highest value of total phenolic   and rosmarinic acid were observed in shoots   after 14 days of treatment with 100 µM salicylic acid. The elevated level of superoxide anion scavenging activity      and total flavonoids        were obtained from the shoots treated with 50 µM salicylic acid for 14 days. Over all treatment with100 µM salicylic acid for 14 days was better in order to antioxidant activity and compounds with recognized antioxidant activity.

The present study aimed to increase the seed germination and the initial performance of pistachio seeds by investigating the effects of the magnetic field and osmopriming treatments simultaneously. 10 treatment levels of 10, 20 and 30 mT for 5, 15, 25 minutes and 1 control treatment (without exposure to a magnetic field) were performed in three replicates and the best level of magnetic surface was selected. The results showed that seeds subjected to the magnetic field showed an increase in plumule length, radicle length, total length of seedlings, fresh and dry weight of plumule as well as radicle and germination speed compared with the control treatment. However, there was no significant difference in the germination percentage and uniformity of seeds. Magnetized seeds, with the superior selective treatment (10 mT for 15 minutes), were primed with solutions of potassium nitrate, humic acid and salicylic acid at levels of 10, 25 and 40 mM and a control level (the best level of magnetism) in three replicates. The best result was obtained from humic acid (25 mM). With regard to the low cost of the purchase or construction of magnetic devices and their positive effects, their application could be recommended (10 mT for 15 minutes) combined with the humic acid (25 mM)) so that the quality of pistachio seedlings production would be increased.