Mineral nutrients have favourable potential in alleviation of salinity problem in plants. Sulfur has specific functions in regulating plant growth, metabolism, enzymatic reactions and osmolyte homeostasis in plants. Hence, an experiment was carried out to explore the role of sulfur in ameliorating salt toxicity in maize by changes in organic and inorganic osmolyte contents. A range of sulfur levels (40, 80 mM) were used to induce salinity tolerance in maize. Various treatments of salinity (25, 75 mM) were applied by using sodium chloride. Results revealed that glycine betaine, proline, total soluble sugars, total soluble proteins and total free amino acids contents were increased by applying salinity while the application of sulfur lowered the proline and increased other studied organic osmolyte contents in all studied maize organs (leaf, shoot, root). The maximum improvement in organic osmolyte contents were found at 40 mM sulfur, however, at 80 mM sulfur proline contents were reduced. Applied salinity increased leaf tissue concentration of Na+ and decreased that of K+, Ca2+, NO3-, PO43-, SO42- leading to a severely declined in K+/Na and Ca2+/Na+ ratio. However, application of sulfur reduced the Na+ contents and improved K+, Ca2+, NO3-, PO43-, SO42-, K+/Na+ and Ca2+/Na+ ratio in the salinity grown plants. Moreover, 40 mM level of sulfur was greatly effective in osmolyte homeostasis at all levels of salinity. This indicated that use of sulfur (40 mM) ameliorated the effect of salinity by changing organic and inorganic osmolyte contents in maize plants.

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One of the major effects of salt stress is high production of reactive oxygen species that adversely affect essential cellular metabolic pathways. To limit the elevated production of reactive oxygen species, plants stimulate various types of antioxidants. In this study, sulfur was used to induce tolerance against oxidative stress through modulation of the activities of various antioxidants. Two maize genotypes (Agatti 2003 and Pak Afgoi 2003) were subjected to different salinity (25 and 75 mM) and sulfur (40 and 80 mM) treatments and a control treatment. Various antioxidants and oxidative stress determinants in maize organs (leaf, shoot, and root) were studied. It was found that salt stress decreased ascorbic acid and tocopherol, but stimulated the production of total phenolics, carotenoids, lycopene, superoxide dismutase, peroxidase, catalase, malondialdehyde, and hydrogen peroxide. Exogenously applied sulfur decreased carotenoids, malondialdehyde, and hydrogen peroxide and increased ascorbic acid, tocopherol, total phenolics, lycopene, superoxide dismutase, peroxidase, and catalase. Agatti 2003 showed higher antioxidant activity than Pak Afgoi 2003. In conclusion, sulfur application at the 40 mM level balanced antioxidants and oxidative stress determinants to induce salt tolerance in maize plants.

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