Análise do efeito do campo magnético na germinação in vitro de variedades comerciais de Solanum lycopersicum L.

Abstract

The growing demand for food created the need for new agricultural production techniques. Studies with biophysical methods such as the magnetic field have shown to be a new, “cleaner” and promising technique for agricultural production, concerning seed treatment, aiming at improving germination, vigor and increasing resistance to environmental stresses. Tomato (Solanum lycopersicum L.) is a crop of high economic, social and nutritional value and, due to its importance, it has gained prominence in research related to magnetic treatment. Given the above, the objective of this work was to evaluate the effect of the magnetic field on the in vitro seed germination of two commercial varieties of tomato: tomato from the Salada group (S. lycopersicum cv 'Gaúcho Melhorado Nova Escolha') and tomato from the Santa Cruz group (S. lycopersicum cv 'Santa Clara 5800'). The methodology consisted of inoculating tomato seeds in test tubes containing culture medium Murashige and Skoog, (1962), with half the concentrations of macronutrients (MS ½ strength), 3% sucrose and, 0,7 % agar, pH 5.8. Then, the seeds were subjected to two intensities of magnetic field (1 mT and 2 mT) inside a Helmholtz coil, for three days, and the control group was kept outside the coil, not being subjected to the magnetic field. For 14 days, morphological parameters were evaluated: germination period, root length, stem length and number of leaves. The end of day 14, fresh mass was measured, and four of the samples were used to measure dry mass. After that, the explants were used for biochemical evaluation of the amount of total soluble proteins, the enzymatic activity of catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POX), and determination of lipid peroxidation by malondialdehyde content (MDA). It was found that only the Gaúcho Melhorado variety obtained a reduction in germination time at the intensity of 2 mT, with 47.4% of the seeds germinated on day 4, differing significantly concerning the control with only 21.1% of the seeds germinated. As for the morphological parameters, there was no significant difference between any of the treatments. It was not possible to determine the amount of total soluble proteins, nor was CAT and APX activity obtained. There was also no significant difference between the POX activity and the control, or in the MDA content, indicating that the treatment with the magnetic field did not result in membrane damage.