Dry mass production and antioxidative enzymatic activity in sunflower seedlings under salt stress conditions supplemented with Salvinia auriculata

The sunflower culture presents acclimatization to the various climatic conditions, thus justifying the prominence and competitiveness in the production of biodiesel in Brazil. However, the semi-arid soil and climate conditions and the current agricultural production model limit the crop, since abiotic stresses such as saline stress cause disturbances in growth, development and reduction of plant productivity. The objective of the work was to evaluate the growth and the antioxidative enzymatic activity of sunflower seedlings under saline conditions supplemented with the macrophyte Salvinia auriculata in the substrate by evaluating the dry mass production and the antioxidative activities dismutase of superoxide (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) in leaves and roots. The experimental design was entirely randomized in which the first arrangement corresponded to a witness without salt and two concentrations of NaCl in aqueous solution (50 and 100 mM of NaCl) and the second arrangement for three types of substrates (sand; sand + commercial humus 80 kg N ha-1 and sand + Salvinia auriculata 120 kg N ha-1), with 5 repetitions per treatment. It was verified that the gradual increase of NaCl concentrations caused a greater decrease in dry mass production. In general, there was an increase in the activities of the antioxidative enzymes, mainly in the plants that received Salvinia auriculata supplementation. The data showed that the supplementation with Salvinia auriculata caused protection against the oxidative damages of the saline stress and minimization of the deleterious effects of the saline stress on the plant growth.