Exposure to Magnetic Fields Reveals a Positive Effect on In Vitro Propagation of Stevia rebaudiana (Bertoni)

Abstract

Magnetopriming in seeds is an established phenomenon and has been successfully carried out in several crops. However, the effect of magnetic fields on in vitro responses has not been studied enough. We studied the effect of exposure to magnetic fields on in vitro nodal explants of a medicinal plant, Stevia rebaudiana, for its propagation through tissue culture. Nodal explants after surface sterilization (ranging in size from 0.5 to 1.5 cm long) were inoculated into test tubes of size 150 × 25 mm with 10 ml of Murashige and Skoog (MS) media supplemented with 0.5 mg/l of 6-benzylaminopurine (BAP). The cultures were exposed to two different magnetic fields of 50 and 100 milli Tesla (mT) for different durations such as 15, 20 and 30 min along with a control in an electromagnetic generator. Further culturing of these explants on to the same media facilitated the growth of the in vitro shoots. Observations on different parameters such as the number of shoots, shoot length and leaves were taken after 40 days of culture. It was found that the cultures exposed to 100 mT for 30 min produced significantly more number of shoots, leaves and the shoot length than the control. The in vitro raised plantlets were successfully hardened. The results of this study indicated that magnetic fields had a positive effect in increasing the efficiency of clonal propagation which is limited by conventional micropropagation techniques. Hence, this novel technology can augment the production of clones of Stevia rebaudiana which can be utilized for commercial extraction of steviosides.