Oxidative Stress and Antioxidant Enzyme Activities in Tomato (Solanum lycopersicum) Plants Grown at Two Different Light Intensities

In the study, oxidative stress statuses and antioxidant enzyme activities caused by light were determined by applying two different light intensities to tomato plants under controlled conditions. The indeterminate type Adamset F1 hybrid tomato (Solanum lycopersicum) cultivar was used. It was grown in Hoagland nutrient solution in a controlled climate room with a light/dark photoperiod of 16/8 h, at 27 °C, 65% humidity. The seedlings were grown by applying two different lights of 400 μmol m⁻¹ s⁻¹, which is the optimum light intensity for tomatoes, and 800 μmol m⁻¹ s⁻¹, which is twice the optimum light intensity. In this study, LED lamps, which are close to sunlight, were used as the light source. Sampling for measurement and analysis was done on the 40th day of the application. The Hoagland nutrient solution was replenished every week. The total fresh plant weights (g) of the plants taken on the 40th day and the chlorophyll, malondialdehyde (MDA) amounts and antioxidative enzyme activities of the leaf samples taken from the middle part of the plants were examined. In addition, the amount of MDA and the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbic peroxidase (APX), which are antioxidant enzymes found in the defense system of plants against stress, were determined in order to understand whether oxidative stress occurs. The total fresh weight, chlorophyll and MDA amounts of the plants grown at high light intensity were found to be higher than the optimum light intensity. It has been observed that there is an increase in antioxidative enzyme activities due to the low level of oxidative stress in plants grown at high light intensity. However, it is understood that the resulting stress is at a tolerable level within the antioxidative defense system.