Abstract

The aim of this study was to evaluate the interaction between salinity, growth, and enzymatic antioxidants in cotton, cowpea and sorghum. Salt stress significantly reduced plant growth, especially in cowpea. Na⁺ and Cl^- concentrations increased in leaves and roots of these three species, especially for cotton at 4.0 and 8.0 dS/m, in relation to control. Salinity significantly increased lipid peroxidation levels in cowpea, whereas in cotton these levels were reduced. Superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) enzyme activities in leaves were not changed by saline treatments at 4.0 and 8.0 dS/m. However, reductions were observed in the SOD activity in cotton at 8.0 dS/m NaCl and in CAT activity in sorghum at 4.0 and 8.0 dS/m. The growth results obtained confirmed the highest cotton tolerance and the highest cowpea susceptibility to salinity, while antioxidant enzyme activities changes suggest that cotton constitutive enzyme system seems to be more efficient than the others.

Key words: Salt stress, antioxidant enzymes, inorganic solutes, Gossipium hirsutum, Vigna unguiculata, Sorghum bicolor.