Cold atmospheric plasma is a green technology that represents a good solution for improving plant properties, in the face of increasingly frequent natural disaster and growing population. Plasma is defined as the fourth state of matter. It is created when gas is exposed to a strong electric field, which leads to ionization, dissociation and excitation of gaseous molecules. Cold atmospheric pressure plasma (CAP) generated from air possesses unique properties, such as strong electric field, plasma produced UV photons and mostly high concentrations of reactive oxygen and nitrogen species. The main purpose of the present research was to investigate the effects of CAP on the adventitious regeneration of leaf explants from african violets (Saintpaulia ionantha L.) and tobacco (Nicotiana tabacum L.) and to identify the most optimal plasma treatment parameters to enhance their growth and differentiation. The research involved the preparation of leaf explants, inoculation of explants on culture media and their exposure to air plasma effluent for different time durations (0 s, 15 s, 30 s, 60 s, 120 s and 240 s). Two different discharge regimes were used: low and high discharge power. We also measured the pH of medium and did optical emission spectroscopy and Fourier transform infrared spectroscopy of plasma discharge and gaseous phase, respectively. After one month of incubations, the weight of the cultured leaf explants was measured and the number of developed shoots and roots counted. The results showed that plasma stimulated callus formation, but only in tobacco. The data also showed that plasma has an influence on medium pH and positive effect on the organogenesis of the shoots, but only under one discharge conditions (5 s, low discharge power). In the other conditions there were no statistically significant differences compared to the control.
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