Effect of exogenous silicon and salt stress on germination and seedling establishment in Borago officinalis

Borage (Borago officinalis L.) is a valuable medicinal plant with a high content of gamma linolenic acid. Seed germination and early seedling growth are critical stage for plant establishment and production.One of the most problems in the field of plant cultivation and production of this plant, is low and uniform seed germination. In addition salt stress in the soil or water is the major factor especially in arid and semi-arid regions which greatly influence plant growth and yield. Thus, in this experiment the influences of exogenous silicon (si) concentration and salinity tolerance during germination and early seedling growth was evaluated. Treatments were 5 levels of silicon (0, 0.2,0.5,0.7,1 mM Na₂SiO₃) and 5 levels of NaCl (0, 20, 40, 80, 100 mM NaCl) in 3 replicates. The results showed that different treatments of salinity and si had considerable effect on the germination rate (GR), germination index (GI) and seedling growth of borage. In all of the si level, seeds possessed more germination rate and germination index than control. The highest germination percentage were obtained at 1 mM si. Significant differences in seed germination were also detected among the NaCl concentrations used. The total dry and fresh weight of seedling were increase in si treatment but reduced by increasing NaCl concenteration. Result of this experiment is consistent with the hypothesis that salinity and si have a priming effect and can prepare a suitable metabolic reaction in seeds and improve seed germination performance and seedling establishment.