The effect of silicon on alleviation of salt stress in borage (Borago officinalis L.)

The effects of exogenous silicon (Si) on salt (NaCl)-stressed borage (Borago officinalis L.) plants were investigated in this study. Six levels of Si (0, 0.5, 1, 1.5, 2, 2.5 mM) and two levels of NaCl (0 and 120 mM) were applied to study the effect of NaCl and Si on some physiological, biochemical and anatomical properties of Borago officinalis L. Salt stress reduced fresh and dry weight, protein contents and catalase activity. In contrast, proline, glycine betaine, malondialdehyde and activity of superoxide dismutase and ascorbate peroxidase increased in salt-stressed plants. The results of anatomical study of leaf cross section showed that salt stress resulted in noticeable anatomical variations such as increase in thickness of leaf blade and thickness of palisade parenchyma cells. Other interesting variations in salt stress include changes in structure and numbers of trichome and stomata. Si treatment in comparison with the plants only treated with salt resulted in an improvement in the studied physiological parameters, especially at 1.5 mM level. Also, Si treatment could moderate the negative effects of salt treatment on the studied anatomical attributes.