The effect of different concentrations of sodium nitroprusside (SNP) on some morphological, physiological and biochemical traits of Zinnia elegans under salinity stress

Salinity is one of the environmental factors that has a critical influence on plant growth and development. Researchers have shown that some plant growth regulators such as nitric oxide improves the plants resistance to environmental stresses such as salinity, heat, cold and drought. Sodium nitroprusside (SNP) commonly was used as a nitric oxide (NO) donor in plants. The aim of this research was to evaluate the role of SNP on salt tolerance of Zinnia elegans and its effects on some morphological, physiological and biochemical characteristics of this plant. A factorial experiment based on completely randomized design was conducted with five levels of salinity 0 (control), 25, 50, 75 and 100 mM NaCl and four levels of sodium nitroprusside (SNP) (foliar spray) 0.0 (control), 0.25, 0.50 and 0.75 mM with 3 replications. In salinity level of 50 mM, the length of stem and root was reduced 41.22 and 29.63 percent in compared to control. In salinity level of 50 mM, application of 0.5 mM sodium nitroprusside, increased total antioxidant capacity, glycine betain and proline 1.93, 3.98 and 2.12 times respectively compared to control. It also increased ascorbate peroxidase, catalase and guaiacol peroxidase 5.15, 4.69 and 2.78 times respectively compared to control. The application of SNP (especially at salt concentrations lower than 50 mM) ameliorated the adverse effects of salt stress, in Zinnia elegans plant.