Influence of Exopolysaccharide-Producing Bacteria and SiO2 Nanoparticles on Proline Content and Antioxidant Enzyme Activities of Tomato Seedlings (Solanum lycopersicum L.) under Salinity Stress

A greenhouse experiment was conducted to evaluate the effects regarding inoculation of exopolysaccharide (EPS)-producing bacterium, the extracted EPS and silicon nanoparticles on Solanum lycopersicum L. seeds under salinity stress, in a completely randomized factorial design with three replicates. The inoculated seeds with silicon nanoparticles (8 gr L-1), bacterial EPS (0.01 M), and 1 mL of bacterial suspension (1x10(8) CFU mL(-1)) were sown in pots and irrigated with water at different salinity levels (0.3, 2, 4, 6, and 8 dS m(-1)). Results showed that treatment application could enhance salinity tolerance of tomato seeds and improve plant growth so that combined treatments of EPS and silicon nanoparticles (S.E.N), bacteria and silicon nanoparticles (S.B.N), and EPS with silicon nanoparticles and bacteria (S.E.B.N) were the best treatments for plant growth and improvement regarding salinity levels. The mentioned treatments significantly (p<0.01) increased root and shoot fresh or dry weight in comparison to the control sample. In addition, treatments significantly (p<0.01) decreased proline content and antioxidant enzyme activities. Thus, it can be concluded that applied treatments are suitable for agricultural and environmental applications and bring about less damage caused by salinity stress.