Document Type : Original Article
In this research we investigated the role of Si in improving salt tolerance in the medicinal plant Borago officinalis L. Borago was pretreated with 0, 0.5 and 1.5 mM Si (as sodium silicate, Na2(Si O2)3) and then treated with four levels of NaCl, namely, 0, 60, 90 and 120 mM NaCl. Then the effects of silicon and NaCl were observed on some physiological and biochemical parameters such as lipid peroxidation malondealdehyde (MDA) and other aldehydes, proline, protein and carbohydrate contents. NaCl significantly increased MDA, other aldehydes and proline contents. Addition of 0.5 mM Si decreased the level of reducing sugars in salt-stressed plants in the leaves. But in plants pretreated with Si and then exposed to NaCl, MDA, other aldehydes contents and carbohydrate in the roots decreased significantly. Protein content on the other hand, increased significantly (P<0.05). Results showed that pretreatment with Si can alleviate NaCl stress in the plants under study.