Exogenous Hydrogen Sulphide Protection of Cucurbita ficifolia Seedlings against NaHCO3 Stress

Salinity is one of the main environmental stresses that affect plant growth and development. H₂S plays an important role in a variety of responses against abiotic stresses. This study was conducted to determine the effects of exogenous NaHS, a hydrogen sulphide (H₂S) donor on physiological characteristics of Cucurbita ficifolia seedlings under NaHCO₃ stress. The accumulation of chlorophyll content, malondialdehyde (MDA), soluble protein and soluble sugar along with the activities of superoxide dismutase (SOD) and peroxidase (POD) in leaves were estimated. NaHCO₃ stress decreased the chlorophyll content, increased the accumulation of MDA, soluble protein and soluble sugar, and improved SOD and POD activities in leaves, compared to the control. However, exogenous NaHS treatment (1.0 mmol/L) significantly increased the chlorophyll content, soluble protein and soluble sugar contents, and decreased the MDA content, SOD and POD activities of NaHCO₃-stressed seedlings. It is strongly suggested that NaHCO₃ stress inhibits the growth of Cucurbita ficifolia seedlings, while exogenous H₂S can effectively protect Cucurbita ficifolia seedlings against NaHCO₃ stress.