Cleome gynandra L. (C4 plant) shows higher tolerance of salt stress than its C3 close relative, C. viscosa L.

The effect of salt stress on some physiological and anatomical parameters in two species of Cleome, C. gynandra (C4 plant) and C. viscosa (C3 plant) was investigated. Seedlings were grown in potted soil in greenhouse for 3 months, before being subjected to salinity stress. Salinity was induced by adding sodium chloride solution at the concentration of 75 mM for 15 days. Growth and physiological parameters were recorded every three days after addition of NaCl. The results showed that salinity caused slightly higher reduction in plant height of C. gynandra than C. viscosa. A small reduction in chlorophyll content was observed in C. viscosa after 15 days of NaCl treatment. Proline content in roots, stems and leaves of both species was generally unaffected by NaCl treatment. The amount of hydrogen peroxide, malondialdehyde and electrolyte leakage increased in response to NaCl. These parameters, which indicate secondary oxidative stress response, were more affected in C. viscosa than C. gynandra. Significant reductions in leaf thickness, petiole and root diameters, and root vascular cylinder were observed in NaCl-treated plants of C. viscosa compared to control plants. The results suggested that C. gynandra was more tolerant of salt stress compared to C. viscosa.